Hướng dẫn sửa chữa HOWO A7

Howo A7. Electrical equipment

Chapter I
Diagnostics of electrical devices
Special warnings:
1. When carrying out welding work on the vehicle, the connectors of all control units must be disconnected.
2. It is strictly forbidden to install a non-standard battery on the car or use an external battery with an increased voltage compared to its
normal value when starting the engine!
3. It is strictly forbidden to disconnect the connector of the wiring harness of the control unit with any system when the supply
voltage is present on it!
4. During repair work, do not touch unnecessarily the contacts on the electrical connectors. If necessary, ensure that static
electricity is relieved from your hands first!

I Wiring diagram of the entire vehicle
1. Description of the wiring diagram
A complete wiring diagram of all electrical devices on the vehicle is essential to the successful implementation of
repair work. What is especially important for difficult situations, a repair specialist needs a circuit diagram in order to make a
conclusion about the possible cause of the violation and find ways to solve the existing problem.Thus, the first step towards
performing repair work is to familiarize yourself with the complete electrical wiring diagram of the vehicle.
The electrical circuits of the vehicle use a single-wire circuit (for the electrical devices of the chassis in version 08, a two-wire
circuit is used). The nominal voltage in the power circuits is 24V, while the colors of the conductors are coded in capital Latin
letters, as shown below:
Letter

A

Color

Red

B

Black

C
White

D
Yellow

E
Grey

F

G

H

Green

Purple

Orange

I
Blue

K

L

M

N

Blue

Brown

Golden

Pink

Below are fragments of the electrical circuit diagrams of the HOWO7C vehice. In accordance with these diagrams, you can find
information on the features of the structure of electrical circuits, a list of components, voltage values, a description of the “ground”
connection points, etc.

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Howo A7. Electrical equipment

A8

Starter power supply

S4

G1.G2

Accumulator

battery

K28

Mechanical type main
power switch
Main power switch
electromagnetic type

K2

Terminal 15 # of
Power Relay J2

F4,4

F1,1

Fuse in the constant
power supply circuit of
the contact 13.61kg

F4,5

Fuse in the constant
supply circuit of
terminal 15 #

Air dryer fuse

Power switch
G3

M1
S1
X20

JP3

Alternator
Starter
Ignition switch
Switching unit

Deconcentrator

S8/28

F1,2

Ignition switch
fuse

D3.D5

Diode

S14

Transmission neutral

position sensor

F2,1

Fuse in the power
supply circuit of the
EDC30 # contact

Q

R6

Heated seat

F2,4

Fuse in the power circuit
30 #

R11

Air Dryer

KK

Main relay of the
engine management
system

F2,5

Fuse in the power
supply circuit of the
EDC30 # contact

F50

Fuse 5A

PE

PCV valve relay

F4,3

DC power interface 15 #

Seat heating / brake
light fuse

A. Supply voltage
B. Seat heating, dehumidifier

(1) “Negative” battery terminal
(41) Left cab ground connection point
(43) Right cab ground connection point

Figure 6-78 HOWO7C Vehicle Electrical System Diagram

2. Examples of the use of electrical circuit diagrams to solve practical issues in diagnostics A typical malfunction of a car equipped

with an engine with an electronic fuel injection control system is
Start violation occurs. For a Euro II engine, what is the most common cause of a start failure ?Since a start failure on an
engine with electronic fuel injection control can be caused by damage not only to the starting circuits, but also by the
fact that the engine control unit does not detect a start condition. Thus, the engine management system requires
a number of healthy electrical circuits, which can potentially be damaged at several characteristic points.
Below is a description of the power circuits on the HOWO7C car, which allows you to diagnose all their possible malfunctions.

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Howo A7. Electrical equipment

Figure 6-79 HOWO7C Vehicle Power Supply Circuit Diagram
(1) Description of system operation
a. The main switch S4 controls the power supply to terminal 30. As a result, power from terminal JPA.1 of the right control unit is
supplied to terminal 17 of the engine control unit (ECU).
b. When the ignition switch S1 is set to the position corresponding to the start of the engine, the supply voltage is supplied to the
junction block from the contact JPB.4 of the right control unit along the circuit +15. After the +15 V voltage is applied
to the power distributor:
1) The PCV - KP relay is activated, while supply voltage is supplied to the PCV1 and PCV2 components through its closed power
contacts.
2) At the same time, the supply voltage is applied to terminals 46 and 56 of the engine control unit, while the engine control unit
switches contacts 74 and 75 to ground. The main relay KE of the engine management system is activated, as a result of which,
through its closed contacts, the supply voltage is applied to contact + E of the supply voltage distributor:
From contact + E of the power distributor, the voltage through contact XE3.1 is applied to contacts 5, 6 and 7 of the control
unit engine
•

• From contact + E of the power distributor, voltage is supplied via contact XE3.2 to terminals 35 and 76 of the control unit
engine.

• From contact + E of the power distributor, voltage through contact XС1.8 is applied to the neutral position sensor S14
transmissions.
c. When the transmission control lever is in neutral, the contacts of the S14 sensor are closed.
1) After terminal LS3.13, the left control unit receives a transmission neutral (high) signal and the LCD displays an N symbol indicating
transmission neutral.
2) In this case, if the presence of a transmission neutral position signal is detected on terminal 66 of the engine control unit,
contact 42 of the engine control unit is connected to ground through its internal circuits, as a result of which contact 2 of relay
A8 will also be connected to ground.
d. With the S1 ignition switch in 1st position:
1) Terminal 48 of the engine control unit receives a start signal;
2) A start signal is applied to terminal JPE1.3 of the right control unit.
3) In this case, the power contacts of the start relay A8 are closed.

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Howo A7. Electrical equipment
e. Terminal 50 of starter M1 is supplied with voltage, the starter starts to operate and the starting process begins.
(2) Engine start relay circuits

Separate start button on
the vehicle

Start relay coil

Start relay contacts
closed

1. “Positive” terminal of the storage battery 2. Power switch 3. “Positive” terminal of the starter 4. “Positive”
terminal of the generator 5. Terminal 30 of the cab wiring harness 6. “Negative” terminal of the storage battery 7.

Contact of the starter connection with “ground” 8. Contact 50 of the starter 9. Starter relay contact 10. Internal
ground wire of the engine control unit
(3) Search for causes of start violation
Analysis of the above information shows that various factors can be the causes of start failure. To the outside
Start-up can be caused by malfunctions of any of the following components. The following are the most likely causes of a
malfunction:
a. An open or damaged in the diode D3 circuit, as a result of which the PCV valve is not powered.
b. An open or damaged in the KP relay circuit causing no power to the PCV valve
c. Open or damaged in the KP relay circuit, as a result of which power is not supplied to the ECM.
d. Damage to fuse F1.2, F2.1, F2.5, F3.4 caused by a breakdown in the electrical circuit.
e. Open or damage in the gearbox neutral position sensor circuit, as a result of which the engine control unit does not allow the
engine to start.
f. Damage in the contact circuit of the start mode of the ignition switch, which causes the absence of a start signal.
g. Damage to the winding or contact of the start relay, as a result of which there is no start signal on terminal 50 of the starter.
h. Starter damage.
i. The starter motor works, but the engine does not start, for example due to a malfunction in the fuel supply system.

II Check and elimination of malfunctions of a combination of devices
Assessment of the state of the input and output circuits of the display play a very important role in finding the causes of its
malfunctions. Therefore, before starting repair work, make sure that the indicated circuits are in good condition. The instrument
cluster has four important connection lines, the state of which determines the operation of the device. This is pin 5 for connecting
the 24V supply voltage on the C1 connector (pin 30 # for connecting the power), as well as pin 4 on the C1 connector (LIN
communication line circuit, through this contact the left and right control units are connected, the operating voltage is 14-16V) ... In
addition, this is pin 7 on the C1 connector (pin 15 # for connecting the supply voltage from the ignition switch), as well as pin 1 or
pin 3 on the C1 connector (ground connection). If there is a malfunction in at least one of the four indicated conductors, the
instrument cluster will not be able to work normally.
The four above function lines are connected to the C1 connector on the back of the instrument cluster. These lines are also
connected via wiring harnesses and a switching unit to the corresponding terminals on the left and right control units. These
conductors are connected to the following distribution contacts: terminal
30 # of the junction box, terminal 15 # of the

4
junction box, LIN pins, and a ground connection.


Howo A7. Electrical equipment
Terminal 30 # of the junction box: Fuse F5 - 1 is connected via pin 5 of the JPD connector. It is designed to supply
power to terminal 30 # of the left control unit and instrument cluster.
Junction box terminal 15 #: Connected to JPC pin 6 of the right control box (the right control box has a built-in automatic current
limiter) and supplies power from terminal 15 # of the ignition switch to the left control box, instrument cluster and switch brake
light. If the external circuit breaker is activated, the supply voltage to the 15 # circuit is disabled.
LIN conductor: Pin 3 on the JPC connector of the right control unit is connected to the corresponding conductors for the
communication with the left control unit and instrument cluster.
Contact for connecting “mass” of the switching unit: Connected to the circuits of the “mass” of the left control unit, instrument
cluster and rocker switch.
1. Symptoms of malfunctions and the procedure for checking the instrument cluster.
Symptoms of malfunctions: The instrument cluster does not work or the display of information on its screen is not
in an appropriate manner. Checking procedure:
(( with ground conductors connected to them). Make sure that the supply voltage is present on the above conductors, in the absence
of voltage, check the reliability of the connection of the above main conductors to the switching unit.
(2) If the main functional circuits of the instrument cluster are OK, but the device does not work, replace the instrument cluster.
(3) If the instrument cluster gauge arrows work normally, but the display does not show any information, replace the instrument
cluster.
2. Symptoms of malfunctions and the procedure for checking various devices of the instrument cluster
(1) Symptoms: Speedometer does not work
Checking procedure:
Disconnect the instrument cluster C2 connector. Connect the wire to pin 8 of the C2 connector of the instrument cluster,
then briefly touch the indicated wire to the “ground”. If the speedometer needle deviates sharply, this indicates that there is no
malfunction of the instrument cluster. Check the installation of the device, the condition of the signal transmission wires, the ground
connection wires and the 12V power supply of the speedometer sensor.
(2) Symptoms of malfunctions: The tachometer does not work

Checking procedure:
Disconnect the instrument cluster C2 connector. Connect the wire to pin 9 of the C2 connector of the instrument cluster,
then briefly touch the indicated wire to the “ground”. If the tachometer needle deviates sharply, this indicates that there is no
malfunction of the instrument cluster.
Verify that the alternator has a pulse output on track W, then check the harness connector.
(3) Signs of malfunctions: Fuel gauge does not work
Checking procedure:
Use a multimeter to check that the resistance between C2 track 1 and ground is between 10-180 . Another test method can be
connecting a 100 resistor between the specified contact and contact 1 of the ground connection on the C2
connector. If, when the indicated resistor is connected, the pointer arrow moves, this indicates that there is no
malfunction of the instrument cluster. Next, make sure that the sensor, electrical connectors and ground
connections are in good condition.
(4) Signs of malfunction: Air brake pressure gauge 1 does not work
Checking procedure:
Using a multimeter, make sure that the resistance between pin 2 of the C2 connector and the “mass” is in the range of 10-184 .
Another method of verification may be to connect a 100 resistor between the specified con-clock and the mass
connection pin 1 on the C2 connector. If the pointer needle moves when the specified resistor is connected, this
indicates that there is no malfunction of the instrument cluster.

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Howo A7. Electrical equipment
Next, make sure that the sensor, electrical connectors and conductors of the connection to the “mass” are in good condition.
(5) Symptoms of malfunction: Air pressure indicator 2 in the pneumatic braking system does not work
Verification procedure:
Using a multimeter, make sure that the resistance between pin 3 of the C2 connector and the “mass” is in the range of 10-184 .
Another method of verification may be to connect a 100 resistor between the specified contact and the mass
connection pin 1 on the C2 connector. If the pointer needle is moved when the specified resistor is connected, this
indicates that there is no malfunction of the instrument cluster. Next, make sure that the sensor, electrical

connectors and conductors of the connection to the “mass” are in good condition.
(6) Symptoms of malfunction: The oil pressure indicator does not work
Verification procedure:
Using a multimeter, make sure that the resistance between pin 4 of the C2 connector and the “mass” is in the range of 10-184 .
Another method of verification may be to connect a 100 resistor between the specified contact and the mass
connection pin 1 on the C2 connector. If the pointer needle is moved when the specified resistor is connected, this
indicates that there is no malfunction of the instrument cluster. Next, make sure that the sensor, electrical
connectors and conductors of the connection to the “mass” are in good condition.
7) Symptoms of malfunction: Coolant temperature indicator does not work
Verification procedure:
Using a multimeter, make sure that the resistance between pin 7 of the C2 connector and the “mass” is in the range of
22.7-287.4 . Another method of verification may be to connect a 100 resistor between the specified pin and the
mass connection pin 1 on the C2 connector. If the pointer needle moves when the specified resistor is connected,
this indicates that there is no malfunction of the instrument cluster.
Next, make sure that the sensor, electrical connectors and conductors of the connection to the “mass” are in good
condition.
3. Signs of malfunctions associated with the disruption of the operation of light alarms and indicators on
combinations of applications, as well as the procedure for their verification
(1) Symptoms of malfunctions: After starting the engine, the battery charging indicator remains on The verification
procedure:
Check if there is a generator voltage on pin 5 or pin 6 of the JPE/RS1 connector of the right control unit.
If there is a voltage, the 43rd numeric parameter on the input display window must be set to “0”, otherwise its value must be “1”.
(2) Symptoms of malfunction: When the engine is started, the beep is activated and the indicator light of the 1st contact air
pressure sensor remains on.
Verification procedure:
Check if the 1st light on the instrument cluster is lit and also make sure that the 25th digital parameter is on
on the working window of displaying input signals is set to “1”. If the display shows the specified value “1”, check the input circuit
from pin 2 on the LS3 connector of the left control unit for a short circuit, and then make sure that the 1st air pressure sensor is
working properly.
(3) Symptoms of malfunction: When the engine is started, the beep is activated and the indicator light of the 2nd contact air

pressure sensor remains on.
Verification procedure:
Check if the 2nd light on the instrument cluster is on and also make sure that the 26th digital parameter is on
on the working window of displaying input signals is set to “1”. If the display shows the specified value “1”, check the input circuit
from pin 9 on the LS3 connector of the left control unit for a short circuit, and then make sure that the 2nd air pressure sensor is
working properly.
(4) Symptoms of malfunction: When the engine is started, an audible signal is activated and the indicator light of the contact air
pressure sensor remains on.
Verification procedure:
Make sure that the 22nd numeric parameter on the input display window is set to “1”. If on the screen
the specified value “1” is displayed, check the input circuit from pin 11 on the LS3 connector of the left control unit for short-circuit,
and then make sure that the contact air pressure sensor is working properly.

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Howo A7. Electrical equipment
(5) Malfunction: When the engine is started, the beep is activated and the indicator light of the contact sensor of the fuel pressure
detector remains on.
Verification procedure:
Make sure that the 57th numeric parameter on the input display operation window is set to “1”. If on the screen
the specified value of “1” is displayed, check the input circuit from pin 8 on the JPE / RS1LS3 connector of the right control unit for
a short circuit, and then make sure that the contact sensor of the fuel pressure signal is working properly.
(6) Malfunction sign: When the engine is started, an audible signal is activated while the illumination light of the cab lock contact
sensor remains on.
Verification procedure:
Make sure that the 56th numeric parameter on the input display window is set to “1”. If on the screen
the specified value of “1” is displayed, check the input circuit from pin 16 on the JPE / RS1 connector of the right control unit for a
short circuit, and then make sure that the contact sensor of the cab lock signal is working properly.

III. Checking and Troubleshooting the Control Unit
If the instrument cluster is working properly, analyze the possible causes of malfunctions by viewing the operating
windows of the input/output signals. If it is decided to check all the input and output signals of the system, first
make sure that the main function circuits of the left control unit are in good working order and connected correctly,
as well as that there is a normal connection between the left and right control units.
Check the 4 main functional circuits as well as the status of the left control unit: pin 4 or 12 on the LS2 connector of the 24V supply
voltage (input circuit 30# supply voltage), pin 3 or 10 on the LS2 connector of the supply voltage of 24V (input circuit 15# supply
voltage), pin 21 on the LS2 connector (LIN communication line, it provides a connection of the combination of pri-borons with the
right control unit, the voltage in the line is 14-16V), as well as pins 1 or 17, 18, 19 on the LS2 connector (connecting the “mass”).
If there is a malfunction in the circuit of at least one of the four specified contacts, the left control unit will not be able to work
normally.
Check the 3 main functional circuits, as well as the status of the right control unit: Pin 3 on the JPC connector (LIN communication
line, it provides communication of the instrument cluster with the right control unit, the voltage in the line is 14-16V), as well as pin 6
on the JPC connector of the circuit 15# connecting the supply voltage from the ignition switch and pin 5 on the JPD connector (circuit
30# of the power supply voltage from the battery). If at least one of these three conductors malfunctions, the system as a whole will
not be able to work normally.
1. Sequence of operations in diagnosing faults of the display control unit
(1) Malfunction indication: The display screen displays the message “main control panel unknown”, the car’s
systems are generally not working, and the screen is flashing to warn of a malfunction.
Verification procedure:
Check pins 4 and 12 on the LS2 connector of the left control unit for a supply voltage (30#)
proCheck pins 3 and 10 on the LS2 connector for the ignition switch supply voltage (circuit 15#)
pin 21 (LIN line) on
the LS2 connector
pins 1, 17, 18, and 19 on the LS2 connector (mass connection).
If there is a violation on the
above contacts, check the status of the power lines (circuits 15#, 30#) on the switching unit, as well as check for a
break in the conductors of the LIN communication line and the reliability of the “mass” connection. If the main
function lines of the left control unit are working properly, but the signs of a malfunction persist, replace the left
control unit.

(2) Malfunction Symptom: The display screen displays the message “main control panel unknown”
Not recognized), but the car’s systems are generally operating normally.
Verification procedure:
Check pin 4 of the C1 connector of the instrument cluster (communication line, operating voltage in the range of
14-16V) if the specified
There is a breach of the circuit, check the cab LIN communication line circuit for any faults.
If no violations are found in the above chains, but there are signs of a malfunction, replace the combination of
applications.
boar.

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Howo A7. Electrical equipment
(3) Malfunction Sign: The display screen displays the message “driving plate unknown”, the vehicle’s systems are generally not
working, and the screen is flashing to warn of a malfunction.
Verification procedure:
Check pin 3 of the JPC connector of the right control unit (LIN communication line, operating voltage: 14-16V) if there is a
violation in the specified circuit, this malfunction will affect the communication between the left control unit and the
instrument cluster through the wire connecting pin 21 of the LS2 connectors of the left control unit and pin 4 of the C1
connector of the combi-nation instruments.
If no violations are found in the above chain, but there are signs of a malfunction, replace the right control unit.
(4) Malfunction Indication: The display displays the message “main control panel unknown” and only the light indicator and light
alarm are working properly.
Verification procedure:
Check pins 3 and 10 on the LS2 connector of the left control unit connected to the power circuit from the ignition switch (circuit 15#)
check pin 4 on connector C1 of the instrument cluster (LIN communication line, operating voltage: 14-16V)
if
there is a violation in the above circuits, check for the supply voltage from the ignition switch (circuit 15#) on the
switch unit located below the steering wheel, and the absence of a break when connecting the conductor of the

LIN communication line to the specified switching unit.
If no violations are found in the two above chains, but there are signs of a malfunction, replace the left control unit.
2. Signs of malfunction of the JPF connector of the right control unit and the corresponding verification operations / seriality of service
procedures
(1) Fault indication: The alarm device does not turn on
Verification procedure:
On the input parameters working window, make sure that the 13th digit parameter is set to 1. If the value is specified
The parameter is 1, make sure that there is a voltage of any magnitude on pin 2 of the JPF connector of the right control unit, and
check that there is no short circuit or break in the wiring harness, and also make sure that the alarm lamp is not damaged.
(2) Malfunction Sign: Lifting platform does not work
Verification procedure:
On the input parameters work window, make sure that the 31st digit parameter is set to 1. If the value is specified
1, make sure that there is any voltage on pin 7 of the LS2 connector in the left control unit. If the value of the specified parameter is
not set to 1, check what the value of the 12th digit parameter is on the input parameters working window. If it is 1, make sure that
there is a voltage on pin 2 of the JPF connector in the right control unit. In the preliminary case, there is a short circuit or break in
the wiring harness of the lifting device. If the value of this parameter is not set to 1, make sure that pin 14 of the LS1 connector of
the left control unit has a connection to the “mass”, and also make sure that the flip switch is working properly.
(3) Malfunction: The engine brake in the exhaust system does not work, but when the engine brake switch is pressed, its indicator
light turns on.
Verification procedure:
If an “exhaust brake malfunction” message appears on the display screen, check the circuit
Pin 7 on the JPF connector of the right control unit for short circuit. If there is no fault message on the display screen, check the
output circuit of pin 7 on the JPF connector for a break.
(4) Malfunction: The engine brake in the exhaust system is not working and the indicator light does not turn on when the engine
brake switch is pressed.
Verification procedure:
After checking the engine brake switch, make sure that the value of the 29th digital parameter on the working window
the input parameters are 1, and then verify that there is an input voltage on pin 2 of the LS2 connector in the left control unit.

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Howo A7. Electrical equipment
(5) Fault indication: The power take-off device is not working, the power take-off switch indicator is not lit.
Verification procedure:
After checking the serviceability of the flip switch of the power take-off device, make sure that the value of the 8th digital pair is
the meter on the working window of the input parameters is 1.
(6) Fault indication: The power take-off device is not working, the power take-off light is flashing. Verification procedure:
Make sure that the PTO position sensor is working properly. If the position sensor signal after onThe power take-off device is not registered by the control unit for 8 seconds, turn off the power take-off device.
(7) Fault sign: The power take-off device is not working, the power take-off light is on. Verification procedure:
If on the display screen there is a fault message, check for a short circuit in the output circuit of the conClock speed 11 on the JPF connector of the right control unit. If there is no fault message on the display screen, check for a break in
the output circuit of pin 11 on the JPF connector of the right control unit.
(8) Fault sign: The center differential lock is not working, the differential lock indicator is not lit.
Verification procedure:
After checking the serviceability of the switch switch of the center differential lock device, make sure that the value of the switch is
The 11th digital parameter on the working window of the input parameters is 1,
(9) Fault symptom: The center differential lock is not working, the differential lock indicator is not working.
Verification procedure:
Make sure that the position sensor of the center differential lock device is working properly. If the signal is positional
The sensor after turning on the locking device of the center differential is not registered by the control unit for 8 seconds, turn off
the power of the differential valve between the shafts.
(10) Fault symptom: The center differential lock is not working, the differential lock indicator is lit.
Verification procedure:
If there is a fault message on the display screen, check for a short circuit in the output circuit
Clock speed 9 on the JPF connector of the right control unit. If there is no fault message on the display screen, check for a break in
the output circuit of pin 9 on the JPF connector of the right control unit.
(11) Fault sign: The cross-axle differential locking device is not working, the diffuser lock indicator is not lit.
Verification procedure:
After checking the serviceability of the flip switch of the inter-wheel differential lock device, make sure that the switch is significant
The 10th digital parameter on the working window of the input parameters is 1.

(12) Fault sign: The cross-axle differential lock is not working, the differential lock indicator is flashing.
Verification procedure:
Make sure that the position sensor of the cross-wheel differential lock device is working properly. If the position sensor signal is not
recorded by the control unit within 8 seconds after turning on the locking device of the cross-axle differential, disconnect the power
to the differential valve between the wheels.

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Howo A7. Electrical equipment
(13) Fault sign: The cross-wheel differential lock is not working, the differential lock indicator is lit.
Verification procedure:
If there is a fault message on the display screen, check for a short circuit in the output circuit
Clock speed 10 on the JPF connector of the right control unit. If there is no fault message on the display screen, check for a break in
the output circuit of pin 10 on the JPF connector of the right control unit.
(14) Malfunction: All-wheel drive is not working, the all-wheel drive indicator is not lit. Verification procedure: After checking the
health of the all-wheel drive flip switch, make sure that the value of the 12th digit parameter is on
the working window of the input parameters is 1.
(15) Malfunction symptom: All-wheel drive is not working, the all-wheel drive indicator is flashing.
Verification procedure:
Make sure that the position sensor of the all-wheel drive switching device is working properly. If the position sensor signal is onAfter turning on the all-wheel drive is not registered by the control unit for 8 seconds, turn off the power to the all-wheel drive valve.
(16) Fault symptom: All-wheel drive is not working, the all-wheel drive indicator is lit.
Verification procedure:
If there is a fault message on the display screen, check for a short circuit in the output circuit
Clock speed 12 on the JPF connector of the right control unit. If there is no fault message on the display screen, check for a break in
the output circuit of pin 12 on the JPF connector of the right control unit.
(17) Fault sign: There is no transition to the neutral position of the power take-off device (before that the power take-off device was
working)
Verification procedure:
if the value of the 9th digit parameter on the working window of the input parameters does not match 1 make sure that the input

parameters are correct
flip-up power take-off switch. If the value of the 9th digit parameter on the input parameters window is 1, and a malfunction message
appears on the display screen, check for a short circuit “mass” in the circuit of pin 8 on the JPF connector of the right control unit.
If there is no invalidity message on the display screen, check for a break in pin 8 on the JPF connector of the right control unit.
3. Signs of malfunction of the JPG connector of the right control unit and the corresponding verification operations / consistency of
service procedures
(1) Fault sign: The air conditioner is not working
Verification procedure:
if there are no fault messages on the display screen check for a supply voltage on the pin
1 JPG connector, and also make sure there is no break in the power supply circuit of the air conditioner.
If a malfunction message appears on the display screen before the engine starts, such as “air conditioner
malfunction”, check the fuse F5_3 and relay J3. If the message “air conditioner branch circuit over-current” appears on the display
screen, make sure that there is no short “mass” in the external circuit from pin 1 on the JPG connector.
(2) Fault sign: Wiper function violation
Verification procedure:
If the wiper does not restart, make sure the J7 relay has 5 pins. In addition, when the windshield wiper is operating
Make sure that the power supply voltage appears periodically on pin 2 of the JPG connector of the right control unit. In the opposite
case, check the windshield wiper motor restart circuit and the electrical connector.

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Howo A7. Electrical equipment
If the intermittent wiper knob is not working, make sure that the value of the 45th digital pair on the operating window of the input
parameters is 1. If the value of this parameter is 1, make sure that the power supply voltage appears periodically on pin 4 of the JPG
connector. If the value of the specified parameter does not match 1, check the combo switch. If the message “intermittent wiper
branch circuit over current” appears on the display screen, make sure that there is no “mass” short circuit in the external circuit from
pin 4 on the JPG connector.
If the washer does not work, make sure that the value of the 44th digital parameter on the operating window of the input parameters is
equal to

1. If the value of the specified parameter is 1, make sure that the power supply voltage appears periodically on pin 4
of the JPG connector. If the value of the specified parameter does not match 1, check the combo switch. If the
message “intermittent wiper branch circuit over current” appears on the display screen, make sure that there is no
“mass” short circuit in the external circuit from pin 4 on the JPG connector.
(3) Malfunction: The dipped beam of the headlamps does not turn on.
Note: The dipped beam headlamps do not turn on until the overall lights are switched on. In this case, the value of the 2nd digitThe parameter on the working window of the input parameters must be equal to 1.
Verification procedure:
If you do not see any fault messages on the display screen, make sure that the value of the 19th digit setting is on
the
the working window of the input parameters is 1. If the value of this parameter is 1, make sure that there is a
supply voltage on pin 3 of the JPG connector. If there is no supply voltage, check the output circuit for a break. if
the value of this parameter does not match 1 check the combo switch
If the message “dipped beam malfunction” appears on the display screen, check the fuse F5_4 and relay J8. If the message “dipped
beam branch circuit over current” appears on the display screen, make sure that there is no short circuit for “mass” in the outer
circuit from pin 3 on the JPG connector.
(4) Malfunction: The high beam headlamps are not switched on.
Note: If the high beam headlamps do not turn on until the overall illumination is on, the value of the 2nd digital
the parameter on the working window of the input parameters must be equal to 1.
Verification procedure:
If no fault messages appear on the display screen, make sure that the value of the 18th digit setting is on the
the operating window of the input parameters with the high beam indicator turned on is 1. If the value of this setting is 1 when the
high beam indicator is on, make sure that there is a power supply voltage on pin 5 of the JPG connector, and also make sure that
there is no break in the output circuit. if the value of this parameter does not match 1 and the high beam indicator is not lit check
the combo switch
If a “high beam malfunction” message appears on the display screen, check the fuse F5_5 and the J4 relay. If the message “high
beam branch circuit over current” appears on the display screen, make sure that there is no short circuit in the “mass” in the outer
circuit from pin 5 on the JPG connector.
(5) Malfunction sign: The overall lighting is not switched on. Verification procedure:
If no malfunction messages appear on the display screen, turn on the overall lighting and make sure that the value
The 2nd digital parameter on the working window of the input light parameters is 1. If the value of this parameter is 1, make sure that

there is a power supply voltage on pin 7 of the JPG connector, and make sure that there is no break in the output circuit. If the value
of the specified parameter does not correspond to 1, make sure that the overall lighting switch is in good condition and check the
“mass” connection circuit.
If a “position lamp malfunction” message appears on the display screen, please check the fuse F6_1 and the J9 relay. If the message
“position lamp branch circuit over current” appears on the display screen, make sure that there is no short circuit in the external
circuit from the control 7 on the JPG connector.

11


Howo A7. Electrical equipment
(6) Malfunction Sign: Front fog lights do not turn on
Note: If the front fog lamps do not turn on until the overall lighting is on, the
The 2nd digital parameter on the working window of the input parameters should be equal to 1.
Verification procedure:
If no malfunction messages appear on the display screen, make sure that the value of the 3rd digit parameter is on
the slave parameter.
than the input parameter window with the front fog lamp indicator on is 1. If the value of the specified parameter with
the fog light indicator on is 1, make sure that there is a power-spinning on pin 9 of the JPG connector, and also
make sure that there is no break in the output circuit. If the value of the specified parameter does not correspond to
1 and the fog lamp indicator is not lit, check the towel of the front fog lamps.
If the message “Front fog lamp malfunction” appears on the display screen, check the fuse F6_3 and relay J5. If the message
“front fog lamp branch circuit over current” appears on the display screen, make sure that there is no short circuit in the external
circuit from pin 9 on the JPG connector.
(7) Malfunction: The right-turn indicator lamp is not working.
Verification procedure:
If no fault messages appear on the display screen, make sure that the value of the 20th digit setting is on the
the input parameters working window periodically changes from 0 to 1 and vice versa. If the direction indicator is not on, check the
combo switch. If the direction indicator light is flashing, check the fuse F4_1 and the J1 relay, and then check the turn signal lamp
bulbs.

If the message “direction indicator lamp branch circuit over current” appears on the display screen, make sure that the circuit from
pin 6 on the JPG connector has a sufficient supply voltage level (for example, by connecting an additional control lamp).
(8) Malfunction Symptom: Left Turn Lamp Does Not Work
Verification procedure:
if you do not see any fault messages on the display screen make sure that the value of the 21st digit setting is on the
the input parameters working window periodically changes from 0 to 1 and vice versa. If the direction indicator is not on, check the
combo switch. If the direction indicator light is flashing, check the F4_1 fuse and the J6 relay, and then check the turn signal lamp
bulbs.
If the message “direction indicator lamp branch circuit over current” appears on the display screen, make sure that the circuit from
pin 8 on the JPG connector has a sufficient supply voltage level (for example, by connecting an additional control lamp).
4. Signs of malfunction of the JPN connector of the right control unit and the corresponding verification operations / consistency of
service procedures
(1) Malfunction Symptom: The electrical beep is not working
Verification procedure:
if the value of the 7th digit parameter on the input parameters working window is 1 check the flip switch
Beep. If the value of the 7th digital parameter on the operating window of the input pa-rameters is 0 when you turn on the beep,
make sure that the value of the 27th digit parameter is 1. If the value of the specified parameter is 1, check for the output voltage on
pin 1 of the JPH connector, and also check the connector. if the value of the specified parameter does not match 1 check the beep
switch.
(2) Malfunction sign: The pump of the dimethyl ether supply system with electronic control does not work
Note: Before starting the engine, press the cold start button. When starting the engine, the pump of the dimethyl ether supply system
with electronic control will turn on at the same time. When the engine control unit registers the presence of a D+ signal, at which the
battery charging indicator is turned off, the operation of the dimethyl ether pump system is reduced.
Verification procedure:
If no fault messages appear on the display screen, make sure that the value of the 14th digit parameter is on the page.
The input parameter box is 1 when the cold start switch is on. If the value of the specified parameter is 1, make sure that the battery
charging indicator is turned off and check the status of the contacts in the ignition switch start circuit. If the value of the specified
parameter does not match 1, check the cold start switch.

12

Howo A7. Electrical equipment
If the message “ether bypass malfunction” appears on the display screen, check the output signal on pin 5 of the JPH connector, as
well as the external circuit associated with it, for a break or short circuit.
(3) Malfunction Symptom: The brake light is not working
Verification procedure:
If there are no reports of any malfunction on the display when you press the brake pedal, make sure that
the value of the 23rd digital parameter on the operating window of the input parameters is 1, after which make sure that you-key
brake light is in good condition (a high-level voltage signal should appear during braking).
There are two possible reasons why the message “stop lamp branch circuit malfunction” appears on the display screen. First, the
loading lamp may be damaged, which may cause a decrease in the supply voltage applied to the brake lamp. Second, there may be a
“mass” short circuit in the circuit of pin 6 on the JPH connector, which may cause the current in the stop lamp circuit to be
exceeded.
(4) Malfunction: The rear fog lamp is not working (the rear fog lamp will not be switched on until the overall lights and front fog
lamps are switched on, or until the high beam of the headlamps is switched on).
Verification procedure:
If the flip-up switch of the rear fog lamp stops selecting on the display screen
After any information, make sure that the value of the 4th digital parameter on the operating window of the input parameters is 1, and
then make sure that the specified switch is in working order.
There are two possible reasons why the message “rear fog lamp branch circuit malfunction” appears on the display screen. First, the
loading lamp may be damaged, which may cause a reduction in the supply voltage supplied to the rear fog lamp. Secondly, there may
be a short “mass” fault in the circuit of pin 7 on the JPH connector, which may lead to an excess of the permissible current in the
circuit of the rear fog lamp.
(5) Malfunction: The reversing lamp does not turn on
Verification procedure:
If there are no reports of any malfunction on the display when the reversing gear is engaged, make sure that there is a problem with
the
make sure that the value of the 51st digital parameter on the input parameters working window is 1, and then make sure that the
reversing sensor is in working order. There are two possible reasons why the message “reversing lamp branch circuit malfunction”

appears on the display screen. First, the taillight may be damaged, which may cause a decrease in the supply voltage supplied to the
reversing lamp. Secondly, there may be a short circuit by “mass” in the circuit of pin 8 on the JPH connector, which can lead to an
excess of the permissible current in the circuit of the reversing lamp.

IV. Analysis of fault signs and the order of operations in finding the causes of typical
violations
(1) Malfunction Sign: No messages are displayed on the instrument cluster
Verification procedure:
If other functions are not impaired, this indicates a malfunction of the instrument cluster display. In this case, you should
replace the instrument cluster.
A small-sized backlight lamp is damaged, which can cause the protection of the electrical circuit to be triggered and
cause a deterioration in the protection of the electrical circuit.
collapse of the operation of the instrument cluster. The specified small lamp should be checked and, if necessary,
replaced. All external functions are performed normally, but the pointer arrows do not move and the display screen does not
no messages are being said. Check for supply voltage on pins 5 (supply voltage 30# circuit) and 7 (15# supply voltage circuit) of
the instrument cluster C1 connector, and then check the parameters of the corresponding sensor input signals.
(2) Fault indication: The vehicle is stationary, but the speedometer shows a speed value.
Verification procedure:
Signal disturbance can be caused by disconnecting the “mass” wire in the connector of the car speed sensor. Check
speed sensor.

13


Howo A7. Electrical equipment
(3) Malfunction: Unable to flip through the images on the LCD Display Verification procedure:
The gearbox is not in neutral
The image flip button on the screen is damaged, replace the instrument cluster.
(4) Fault indication: Overestimated or underestimated odometer readings.
Verification procedure:

When the instrument cluster is removed, mileage data is stored. If you need to replace the instrument cluster, set up
The code shall be reset according to the parameters of the new instrument cluster.
(5) Malfunction: The instrument cluster illumination is not activated.
Verification procedure:
To illuminate the instrument cluster, a 24V lamp is used. If the voltage of the on-board network is too high, a small The baritic lamp may be damaged and will need to be replaced.
(6) Fault indication: Overestimated or underestimated odometer readings.
Verification procedure:
When the instrument cluster is removed, mileage data is stored. If you need to replace the instrument cluster, set up
The code shall be reset according to the parameters of the new instrument cluster.
(7) Fault indication: The instrument cluster illumination is not activated.
Verification procedure:
To illuminate the instrument cluster, a 24V lamp is used. If the voltage of the on-board network is too high, a small The baritic lamp may be damaged and will need to be replaced.
(8) Malfunction Sign: Air Conditioning Is Not Working
Verification procedure:
Analysis of the possible cause of the malfunction: After 4 seconds the control system registers the presence of
D+ signal, the J3 relay turns on, its pins are shorted, and the supply voltage through pin 1 of the JPG connector is supplied to the
air conditioner fan. If the D+ signal is unstable, the control system interprets this as start-stop operation of the motor and continues
to keep the J3 relay on, which can lead to a power failure of the conditioner.
Check the D+ voltage output signal on the oscillator and make sure that its parameters are within normal values.
On the engine running, make sure that pins 5 and 6 of the 12-pin JPE connector on the right control unit have a D+ input signal.
Check the fuse F5-3 and relay J3, and then make sure that pin 1 of the JPG connector has an input voltage. Cut the wire connected
to pin 1 of the JPG connector and attach it to pins 3 or 4 of the JPB connector.
Panel.
(9) Malfunction: When the air conditioner is on, the parking lights are on at half the incandescence. After turning on the overall
lighting, the air conditioner stops working.
Verification procedure:
Analysis of the possible cause of the malfunction: The wire of the “mass” of the air conditioning system is disconnected. When you
turn on
of the air conditioner, its power is carried out through a chain of “mass”, connected through the lights of the overall lighting. When
the oversized lights are turned on, the high-level supply voltage appearing on them leads to a cessation of the

supply voltage supply to the air conditioner, which is accompanied by its stopping.
Make sure that the “mass” circuit of the air conditioning control system is reliably connected.

14


Howo A7. Electrical equipment
(10) Malfunction: The message “High beam over current” appears on the display screen.
Verification procedure:
Analysis of the possible cause of the malfunction: The most common cause of this malfunction is the connection to the specified
a chain of additional consumers or the installation of lamps of greater power not provided by the manufacturer. Check the electrical
circuit and install the paws of the installed power.
Disconnect the additional high-beam headlights from the specified circuit, instead connecting them via the driving mode relay.
(11) Fault sign: The lights on suddenly go out. Verification procedure:
Analysis of the possible cause of the malfunction:
1) During the engine start-up period, the system temporarily shuts down the output circuits with high energy consumption.
2) Power to the contact brake sensor is supplied from the circuit 15# of the control system. If the brake sensor is damaged or its
circuit is short-circuited by “mass”, the automatic current limiter in the right control unit stops supplying power to the specified
circuit. At the same time, due to the cessation of power supply through the circuit 15 #, the instrument cluster and the main control
system stop working.
3) The message “high beam branch circuit over current” appears on the display screen. In this case, the system registers the
presence of too much power consumption in the external circuit and, in order to protect it from damage, automatically shuts off the
power supply. Make sure that the D+ output signal on the oscillator is normal.
Make sure that the D+ signal on the generator is normal.
Cut the conductor from pin 16-3 (start signal) on the JPE connector of the right control unit, thereby eliminating altogether
the possibility of registration of the start signal by the system.
Make sure there is a normal signal from the brake sensor. Connect the brake sensor power to other brake cells connected to pin
15#.
Make sure that the “mass” of the flip switch is connected reliably.
Verify that there is a normal output signal on pin 6 of the JPC connector (circuit 15#).

If it is necessary to provide power to additional high-beam headlights, install an additional relay for them so that
Reduce the current through the main power line.
(12) Fault sign: The wiper motor is not working.
Verification procedure:
Analysis of possible caseFault: Power to the wiper motor is supplied from pin 3 on the connector
JPB right control unit. In addition, through the fuse F3 - 5 is supplied power from the circuit 15 #. Make sure that the specified fuse is
working properly.
(13) Fault sign: The wiper blades do not return to their original position.
Verification procedure:
Analysis of possible causes of malfunction: The wiper motor relay (J7) has 5 contacts, other relays have
4 pins. Therefore, improper connection can lead to a violation of the function of returning the wiper to its original position.
Make sure the J7 relay has 5 pins. Also, when the wiper is running, make sure that the power supply voltage appears periodically on
pin 2 of the JPG connector of the right control unit. Otherwise, check the windshield wiper motor restart circuit and connectors.

15


Howo A7. Electrical equipment
V. Ovvervieew off CBCU Blocck Feeattures
1. Configuration of the central control unit of the car body equipment

Table 6-1 CBCU Block Input/Output Interface Channel Configuration Table
Channel name

Central Body Equipment Control Unit - CBCU

Discrete inputs (programmable
analog inputs)

34 discrete (on-off) inputs with a current of 8 mA, including 4 current inputs with an activation

function, as well as 16 discrete inputs with a current of 1 mA, or other discrete inputs of the control
unit, among which one current input has an activation function.
6 analog inputs for sensors
2 inputs for engine speed signal and vehicle speed signal

Analog inputs
Frequency inputs (0-2kHz)
Frequency outputs (0 – 2kHz)

Power outputs

Other outputs
CAN-interface
Other interfaces

4 channels for output frequency signal
25 output channels for control of lamps / solenoid valves with an operating voltage of 24V
4 output relay control channels with operating voltage 24V
1 output control channel with pulse width modulation (PWM) at operating voltage 24V
Light control signal of the instrument cluster and switch on the control panel

2 outputs for power supply of sensors with voltage of 8V 1
output for power supply of sensors with voltage of 5V
2 Line Interface CAN по ISO 11898 (ICAN)
K - line (ISO 9141) Menu
button interface

2. Inputs
The central control unit of the car body equipment can receive analog and discrete input signals.
(1) Discrete inputs with diagnostic function

Configured at the upper and lower limits of the ranges of change of discrete signals with the possibility of their
adjustment,
to ensure the selection of the required control accuracy. In addition, it is possible to diagnose the input data.
(2) Analog Inputs
The type of analog input can be selected via the PLC program. It is possible to select the following modes:
R500: Input 0 - 500 Ohm, which is used for air pressure sensor, oil pressure sensor, temperature sensor
coolant, as well as a fuel level sensor.
RNTC: 0-50k ;
U32V: Measurement of voltages in the range 0 - 32V. This input is used for the input voltage
signal of the D+ generator; U5V: Measurement of voltages in the range of 0 - 5V;
(3) Frequency input
There are two types of frequency input signals: vehicle speed signal and
crankshaft speed signal
Engine.
a. Vehicle speed signal:
Below are the parameters of the car speed sensor signal Lower input voltage
level: UILmax = 1.2V (IILmax = 0.3mA) Upper input voltage level: UILmin =
5.5V
Frequency: UILmax = 1.6KHz
Pulse duration: tmin = 207 s
b. Crankshaft speed:
It is possible to record the frequency of the signal from the W pin of the generator,
which has the following pa-Rameters:
Lower input voltage level: UILmax = 1.2V (IILmax = 0.3mA)
Top level of input voltage: UILmin = 5.5V
Frequency: UILmax = 1.6KHz
Pulse duration: tmin = 207 s
The pulse waveform can be either rectangular or sinusoidal.

16

Howo A7. Electrical equipment
3. Exits
(1) Frequency output (optional)
Allows you to generate 4 pulse signals of the car speed with the following parameters: Lower level of input voltage:
UILmax = 1.5V; (I = 1mA)
UILmin = 5.5V; (I = 1mA)
Frequency: UILmax = 1.6KHz; Pulse duration: tmin = 207 s
(2) Sensor Power Supply
The power supply of the sensors available on the car can be carried out on 3 lines: 5V (1 line) and 8V (2 lines).
(3) Output power lines
All output power lines are divided into 6 groups (G1, G2, G3, G4, G5 and G6), each of which must use
Effective fuse: in groups 1, 2 and 3, a fuse of 15A shall be used; in groups 4, 5 and 6, a fuse with a rating of 20A
shall be used.
All output lines have a short-circuit diagnostic function. In the event of a short circuit, the power supply in the circuit is switched off.
For more information, see the settings blade of the connector D pin-out table below.
A number of outputs have the function of controlling the current in the circuit. For more information on such outputs, see the table
column indicating the parameters marked “SENSE”.
Regardless of whether there is a break or a short circuit in the controlled circuit, if the current exceeds the specified range, the system
will issue a command to display the corresponding error message on the devices.
For some types of consumers requiring significant current or related to inductive devices, it is necessary to supply
power through relays. In these cases, the outputs of the system are used to control the windings of relays, such as
a wiper relay.
(4) Signal output with variable duty cycle
The CBCU has one output for generating a pulse-width modulation control signal, which is used by
Is used to adjust the brightness of the backlight switches at night.

VI. Deescrip
ption off Pin Fuuncctionss on CBCU Conneectorrs

The following figure shows the layout of the connectors in the CBCU:

17


Howo A7. Electrical equipment

Figure 6-80 CBCU Block Connector Layout The pin-out functions on the
connectors of the CBCU are described below in the tables:
Table 6-2 Connector A

№

A01.
A02.
A03.
A04.
A05.
A06.

CBCU SIGNALS
Solenoid valve for inter-wheel
differential locking
Power supply G6, PWR_G6 (Kl.30)
”Ground”
Preheating relay
Center differential lock solenoid valve
Main left side light, left side light,
license plate light

A07.

Front fog lamp

A08.

Power supply G5, PWR_G5 (Kl.30)

A09.

Main right side light, top right side light

PLC USED CONTACT NAMES

OPTIONS

OUT_01

G6,D,H,2.7A

OUT_01_DIAG

SENSE option

PWR_06
OUT_02
OUT_02_DIAG
OUT_04
OUT_04_DIAG

”Ground”
G6,D,H,2.8A
OptionSENSE
G5,D,H,2.7A
Option SENSE

OUT_06

G5,D,H,2.8A

OUT_06_DIAG
OUT_03

Option SENSE
G6,D,H,5.6A,C

OUT_03_DIAG
PWR_05
OUT_05

Option SENSE

OUT_05_DIAG

Option SENSE

G5,D,H,2.8A

Table 6-3 Connector B
№

CBCU SIGNALS

PLC USED CONTACT NAMES

B01.

OUT_SPEED_01

B02.

OUT_SPEED_02

B03.

OUT_SPEED_03

B04.

OUT_SPEED_04

18

OPTIONS


Howo A7. Electrical equipment
B05.

ABS warning lamp

B06.

Not used

IN_DIG_01

D.1mA with programmable level
-

B07.

”Ground”

”Ground”

B08.

”Ground”

”Ground”

B09.
B10.
B11.

Trailer ABS warning lamp
Brake pedal position sensor
Engine preheater operation indicator

IN_DIG_02

D.1мА with programmable level

IN_DIG_03

D.8мА with programmable level

IN_DIG_04

D.8мА with programmable level
-

B12.
B13.
B14.
B15.
B16.
B17.
B18.

Driver door open signal
Seat belt not fastened warning lamp
Low pressure warning lamp in circuit 1 of the
brake system
Low pressure warning lamp in circuit 2 of the
brake system
Low pressure warning lamp in circuit 3 of the
brake system
Pneumatic horn relay

IN_DIG_05

D.8мА with programmable level

IN_DIG_06

D.1мА with programmable level

IN_DIG_07

D.1мА with programmable level

IN_DIG_08

D.1мА сwith programmable level

IN_DIG_09

D.1мА with programmable level

OUT_11

G5,D,H,0.2A

OUT_11_DIAG
B19.

B20.
B21.

Power take-off solenoid valve

Menu button press / Confirm button
Trailer left side light relay

OUT_07

G5,D,H,1.7A

OUT_07_DIAG

(Оption SENSE)

IN_DIG_10

D.1мА сwith programmable level

OUT_08

G5,D,H,1.0A

OUT_08_DIAG
B22.

Not used

B23.

Relay for electrical horn

OUT_09

G5,D,H,0.2A

OUT_09_DIAG
B24.

Low speed and intermittent wiper relay

OUT_10

G5,D,H,0.2A

OUT_10_DIAG

Table 6-4 PARAMETER С
№
C01.
C02.
C03.
C04.
C05.

CBCU SIGNALS

PLC USED CONTACT NAMES

Powertrain High CAN Line (PCAN_H)

PARAMETER
-

Powertrain Low CAN Line (PCAN_L)

-

”Ground” of the CAN line of the power unit

”Ground”

K-line

-

Horn selector switch

IN_DIG_11

D, 1mA, programmable level

C06.

Position 1 of the combination switch (low
beam switch)

IN_DIG_12

D, 8mA, programmable level

C07.

Position 2 of the combination switch (high
beam switch)

IN_DIG_13

D, 8mA, programmable level

IN_DIG_14

D, 8mA,programmable level

IN_DIG_15

D, 8mA, programmable level

C08.

C09.

Menu Button Left Rotation / Page Up
Switch
Position 4 of the combination switch (right
turn signal switch)

19


Howo A7. Electrical equipment

C10.

Position 5 of the combination switch (left
turn indicator switch)

IN_DIG_16

D, 8mA, пprogrammable level

C11.

Reversing light switch

IN DIG 17

D, 8mA, пprogrammable level

C12.

Lighting control

IN_DIG_18

D, 8mA, programmable level

C13.

The signal starts the engine

IN_DIG_19

C14.

MCAN_L_TR

Not Used

C15.

MCAN_L

Not Used

C16.

MCAN_GND

Not Used

«Ground»

IN_DIG_20

D, 8mA, programmable level

IN_DIG_21

D, 8mA, programmable level

IN_DIG_22

D, 8mA, programmable level

IN_DIG_23

D, 8mA, programmable level

C17.
C18.
C19.
C20.

Parking brake position sensor signal
PTO switch
Power take-off neutral position switch
Cross-axle differential lock switch

C21.

Frequency input 1 (Engine speed
signal)

IN_FREQ_01

C22.

Frequency input 2 (Vehicle speed
signal)

IN_VSYSA_Speed

C23.

Not Used

C24.

Not Used

C25.

Not Used

C26.

Not Used

W.H.D, 8mA, programmable
level
120 , connected to MCAN L.

C27.

MCAN_H

Not Used

C28.

MCAN_L

Not Used

C29.

MCAN_GND

Not Used

«Ground»

IN_DIG_24

D, 1mA, programmable level

IN_DIG_25

D, 1mA, programmable level

IN_DIG_26

D, 8mA, programmable level

IN_DIG_27

D, 1mA, programmable level

IN_DIG_28

D, 8mA, programmable level

C30.
C31.
C32.
C33.
C34.

Center differential lock switch
All-wheel drive system switch
Unlocking the warning signal in the cab
Engine Damage Warning Signal
Engine brake switch / signal

C35.

High and low gear sensor

IN_DIG_29

D, 8mA, programmable level

C36.

Menu button rotation to the right / scroll
switch down

IN_DIG_30

D, 8mA, programmable level

C37.

Sensor supply line 1

OUT_SENSOR_PWR_01

Макс. 10 мА

C38.

Sensor supply line 2

OUT_SENSOR_PWR_02

Макс. 10 мА

C39.

Not Used

C40.

Not Used

OUT_33

D,PWM,L,1A

OUT_33_DIAG
C41.

Not Used

OUT 34

D,L,1A

OUT_34_DIAG
C42.

GND circuit of connection “mass”

«Ground»

C43.

Connecting “Ground”

«Ground»

C44.

Connecting “Ground”

«Ground»

C45.

Not Used

-

20


Howo A7. Electrical equipment
C46.

Power take-off neutral solenoid valve

OUT_12

G4,D,H,1A

OUT_12_DIAG

C47.

Not Used

C48.

Relay for right side trailer light

C49.

Not Used

C50.

Main rear fog lamp

C51.

Not Used

C52.

Main reversing light

OUT_13

G4,D,H,0.2A

OUT_13_DIAG
OUT_14

G4,D,H,1.8A,C

OUT_14_DIAG
OUT_14_SENSE
OUT_15
OUT_15_DIAG

G4,D,H,1.8A,C

OUT_15_SENSE

Table 6 - 5 Рrameter D
№

CBCU SIGNALS

PLC USED CONTACT NAMES

W, H.D, 8мА, programmable
level

D01.

Position II of the light switch

D02.

”Ground” sensor

«Ground»

D03.

”Ground” sensor

«Ground»

D04.

”Ground” sensor

«Ground»

D05.

Differential lock signal

D06.
D07.

Front fog lamp switch
Rear fog lamp switch

IN_DIG_31

PARAMETERS

IN_DIG_32

D, 8мА, programmable level

IN_DIG_33

D, 8mA, programmable level

IN_DIG_34

D, 8mA, programmable level

D08.

ASR signal

IN_DIG_35

D, 8mA, programmable level

D09.

Gearbox neutral position sensor
(Neutral switch)

IN_DIG_36

D, 8mA, programmable level

D10.

ICAN_GND

D11.
D12.
D13.

Analog input 1 (air pressure sensor 1)
Analog input 2 (air pressure sensor 2)
Analog input 3 (fuel level sensor in the tank)

«Ground»
IN_ANA_01

Resistance sensor

IN_ANA_02

Resistance sensor

IN_ANA_03

Resistance sensor

D14.

Analog Input 4 - Generator D + Terminal

IN_ANA_04

Voltage sensor

D15.

Analog input 5 (coolant temperature
sensor)

IN_ANA_05

Resistance sensor

IN_ANA_06

Resistance sensor

D16.

Analog input 6 (oil pressure sensor)

D17.

ICAN_H

-

D18.

ICAN_H

-

D19.

ICAN_L

-

D20.

ICAN_L

-

D21.

”Ground” sensor

D22.

Alarm switch

IN_DIG_37

D23.

Light switch position 1 (parking light
switch)

IN_DIG_38

«Ground»
W.H.D, 8mA, programmable
level
W.H.D, 8mA, programmable
level

22

21


Howo A7. Electrical equipment
D24.

Combined switch for intermittent operation
of the windshield wiper

IN_DIG_39

D.8мА с programmable level

D25.

Combined switch for low-speed operation of
the windshield wiper

IN_DIG_40

D.8мА с programmable level

IN_DIG_41

D.8мА с programmable level

D26.

Combined wiper washer control switch

D27.

Signal to return the wiper blades to their
original position

IN_DIG_42

D.1мА с programmable level

D28.

Wheel axle lift confirmation signal

IN_DIG_43

D.1мА с programmable level

IN_DIG_44

D.1мА programmable level

D29.

Power take-off activation confirmation signal

D30.

ICAN_GND

D31.

Power supply of sensors with voltage + 5V

OUT_ANA_PWR

Макс. 20мА / U

D32.

Horn button

IN DIG 45

D.1мА с programmable level

IN_DIG_46

D.8мА с programmable level

IN_DIG_47

D.8мА с programmable level

IN_DIG_48

D.8мА с programmable level

D33.
D34.

D35.

D36.
D37.

«Ground»

All-wheel drive system activation

confirmation signal
Inter-wheel differential lock confirmation
signal
Low oil pressure warning signal (EGR engine)
Water in fuel warning signal
(diesel engine with battery power supply
system)

ADR signal (vehicles with ADR system)

IN_DIG_49

Air filter clogged warning signal

IN_DIG_50

W.H.D, 1mA, programmable level
D.8мА с programmable level

D38.

Not Used

-

D39.

Not Used

-

Not Used

-

table6 - 6 Prameter Е
№
E01.
E02.

CBCU SIGNALS
Connecting “Ground” (Kl.31)
G3 Power Supply (PWR G3)

PLC USED CONTACT NAMES

«Ground»
PWR_03
OUT_21

E03.

Not Used

PARAMETERS

G3,D,H,3.6A,C

OUT_21_DIAG
OUT_21_SENSE

The main lamp of the indicator of the
right turn of the car

OUT_16

G4,D,H,1.8A

E04.

OUT_16_DIAG

(OptionSENSE)

E05.

The main lamp of the indicator of the
left turn of the car

OUT_17

G4,D,H,1.8A,C

OUT_17_DIAG

(OptionSENSE)

The main lamp of a brake light of
the car

OUT_20

G3,D,H,1.8A,C

E06.

OUT_20_DIAG
OUT_20_SENSE
OUT_18

G4,D,PWM,H,2.6A.C

E07.

Rocker switch for lighting
(modulated pulse width signal)

OUT_18_DIAG

(OptionSENSE)

E08.

Power supply G4 (PWR G4)

PWR_04

E09.

dipped headlights

OUT_19

G3,D,H,10A,C

OUT_19_DIAG

OptionSENSE

22


Howo A7. Electrical equipment
Table 6 - 7 Рrameter F
№
F01.

F02.

F03.
F04.
F05.

CBCU SIGNALS
Trailer Right Indicator Indicator
Indicator of the front and rear main
lights of the right direction indicator of
the car
Rear fog lamp for trailer

Trailer brake light
Ignition switch ON position (KL15)

F06.

Power supply G2 (PWR G2)

F07.

The main front and rear lights of the left
turn indicator of the car

F08.

High beam relay

F09.

Connecting “Ground” (Kl.31)
Washer pump motor

F10.

F11.

Trailer reversing light

F12.

Power supply G1 (PWR G1)

F13.

Four-wheel drive / axle lift solenoid
valve

F14.

Air conditioner relay

PLC USED CONTACT NAMES

PARAMETERS

OUT_24
OUT_24_DIAG
OUT_23
OUT_23_DIAG
OUT_23_SENSE
OUT_22
OUT_22_DIAG
OUT_25
OUT_25_DIAG

G2,D,H,5.6A,C
OptionSENSE
G2,D,H,1.8A,C

IN_IGNITION

W,H,1.6мА

G2,D,H,3.6A,C
OptionSENSE
G2,D,H,3.6A,C
OptionSENSE

PWR_02
OUT_27
OUT_27_DIAG
OUT_27_SENSE
OUT_26
OUT_26_DIAG
OUT_29
OUT_29_DIAG
OUT_28
OUT_28_DIAG
OUT_28_SENSE

G1,D,H,1.8A,C

G1,D,H,1.0A,C
(OptionSENSE)
«Ground»
G1,D,H,1.8A,C
(OptionSENSE)
G1,D,H,1.8A,C

PWR_01
OUT_30

G1,D,H,1.0A

OUT_30_DIAG
OUT_31

G1,D,H,1.0A

OUT_31_DIAG

VII. Description of the functions of the contacts on the connectors of the instrument cluster
The instrument cluster can have one connector, as shown in the figure below.

Figure 6 - 81 Diagram of an arrangement of connectors of a combination of devices
A description of the function of the contacts is given in the table below:

23


Howo A7. Electrical equipment
Table 6 - 8 Description of the functions of contacts on the instrument cluster connector
Female pin number
on connector

Appointment

Female pin number on
connector

Appointment

1

KL30

2

KL15

3

KL31

4

5

Not Used

6

K-line
Not Used

7

I-CAN-H

8

I-CAN-H

9

I-CAN-L

10

I-CAN-L

11

Shielded wire I - CAN

12

Not Used

14

Not Used

13

Not Used

Note: Some pins may not be used in a particular vehicle version.

VIII. Troubleshooting
1. Critical failures

In the event of a significant system malfunction, an alarm will be activated on the LCD display of the instrument cluster.
“STOP” jam. When the engine is running, a warning sound will work.
Among the significant are the following malfunctions:
(1) Break in the circuit of the 1st air pressure sensor in the brake system drive (sensor resistance 240 );
(2) Break in the circuit of the 2nd air pressure sensor in the brake system drive (sensor resistance 240 );
(3) Short circuit in the circuit of the 1st air pressure sensor in the brake system drive (sensor resistance 5 );
(4) Short circuit in the circuit of the 2nd air pressure sensor in the brake system drive (sensor resistance 5 );
(5) Low air pressure in the 1st circuit of the brake system (short circuit for “mass” in the contact circuit B15 of the CBCU unit);
(6) Low air pressure in the 2nd circuit of the braking system (short circuit on the “mass” in the contact circuit B16 of the CBCU unit);
(7) Low air pressure in the additional circuit of the braking system (short circuit for “mass” in the contact circuit B17 of the CBCU
unit);
(8) Damage to the oil pressure sensor in the engine (sensor resistance 5 );
(9) Low engine lubrication pressure (oil pressure <0.06Mpa); (10) Cab lock violation; (11) Exceeding the maximum
permissible engine speed (speed >2600 rpm).
Note: If these faults occur, you should stop the vehicle immediately and do not resume driving until these faults are resolved! Failure
to do so may result in inadvertent or damage to the vehicle’s systems!
2. Significant malfunctions
If there are significant malfunctions on the LCD display, the corresponding alarm device will turn on (when
operatingIf at least one of the malfunctions listed below under the numbers 1-9 appears, the buzzer will produce a series of
10 sound pulses following a period of 1c). After all faults are resolved, the buzzer and alarm on the LCD display will
turn off. The warning page on the screen will disappear and the normal normal operation page will appear. Among
the significant are the following malfunctions:
(1) Low fuel level in the tank;
(2) Break in the circuit of the fuel level sensor in the tank (resistance in the circuit of the specified sensor >240 );
(3) Short circuit in the circuit of the fuel level sensor in the tank;
(4) Engine coolant temperature is too high (temperature exceeds 95°C);
(5) Break in the circuit of the engine coolant temperature sensor (the resistance in the circuit of the specified
sensor exceeds 50 K );
(6) Turn on the battery charging indicator (the voltage at the D+ terminal is less than 24V);

24


Howo A7. Electrical equipment
(7) Increased voltage of the on-board network (more than 30V);
(8) Too low voltage of the on-board network (less than 19V);
(9) Warning of excessive clogging of the air filter;
(10) Damage in the G1 power supply circuit of the CBCU;
(11) Damage in the G2 power circuit of the CBCU;
(12) Damage in the G3 power supply circuit of the CBCU;
(13) Damage in the G4 power supply circuit of the CBCU;
(14) Damage in the G5 power circuit of the CBCU;
(15) Damage in the G6 power supply circuit of the CBCU;
(16) Damage to the main brake light of the car;
(17) Damage to the trailer brake light;
(18) Damage to the front and rear lights of the vehicle’s left turn indicator;
(19) Damage to the main lamp of the left turn indicator lamp of the vehicle;
(20) Damage to the left turn lamp of the trailer;
(21) Damage to the front and rear lights of the vehicle’s right-turn indicator lights;
(22) Damage to the main lamp of the right turn indicator lamp of the vehicle;
(23) Damage to the right turn indicator of the trailer;
(24) Damage to the front fog lamps;
(25) Damage to the rear fog lamp;
(26) Damage to the fog lamp of the trailer coupling device;
(27) Damage to the high beam of the headlamps;
(28) Damage to the dipped-beam headlamp circuit;
(29) Damage to the reversing lamp;
(30) Damage to the trailer’s reversing lamp;
(31) Damage to the main left parking lamp of the car;
(32) Damage to the main right-hand clearance lamp of the car;

(33) Damage to the additional lamp;
(34) Damage to the electric motor of the washer pump;
(35) Damage to the solenoid valve of the inter-wheel differential lock;
(36) Damage to the solenoid valve of the center differential lock;
(37) Damage to the solenoid valve of the all-wheel drive;
(38) Damage to the solenoid valve of the power take-off device;
(39) Damage to the solenoid valve for switching on the neutral position of the power take-off device;
(40) The driver’s door is not closed;
(41) Disruption of communication with the ABS system;
(42) Communication with the tachograph (VDO supplies a tachograph that connects to the CAN
bus);
(43) Short circuit on the “mass” in the circuit of the air conditioner relay.
3. System Error Messages and Diagnostic Methods
If there is a malfunction, first check the information on the instrument cluster display and then
perform
Diagnostic procedure according to the recommendations in the table below.
Table 6 - 9 VDO System Malfunction Reports and Possible Causes
Place

Designation of input circuits
and their locations,
descriptions of output circuits

Screen display

25

Possible cause of the malfunction