Slide đào tạo hệ thống phanh ABS trên xe khách

ANTI-LOCK BRAKE SYSTEM
(Heavy Duty Truck)


Learning Goals (You Can…)
 Understand Characteristics of the Anti-Lock Brake System
 State Control Logic
 State input and output element of the system
 Understand System Layout and Location
 Understand how ABS Components are controlled, operated and checked
 Read trouble codes with/without Hi-Scan Pro
 Troubleshoot
 Repair ABS

2


Table of Contents
 Characteristics
 ABS General
 Diagram of Input/Output
 System Layout
 Components Description
 Operational Principle
 Troubleshooting
 Schematic Diagram

3


Characteristics

Exercise
What is the characteristics of the ABS?
Discuss your opinion in the group and make a note of the most important items

 Stability
 Steerability
 Shorter emergency brake distance
 Drastic reduction of vehicle accidents
 Tire protection by avoiding brake flats, thus longer tire service time
 Advertising effect, e.g. for tourist coaches

4


ABS General

5

Brake force coefficient µB as function of brake slip 

Maximum Brake
Force Utilization


ABS General

6

Exercise
A

B

How To Calculate Slip Ratio

SLIP RATIO =

A-B
A

A : Vehicle speed
B : Wheel speed

x 100


ABS General
ABS Control Cycle

7


ABS General

8

Exercise : Diagram of Input / Output
Please fill out input and output element on the block diagram

Front Left
Wheel

Speed
Sensor

Pressure
Module Valve

Front Right

ASR Valve

Rear left
Rear Right

ECU

Warning Lamp
ASR
Information
Indicating

Battery ( + )
Self Diagnosis Initiate Line

Valve Relay
Self Diagnosis


System Layout
Air Over Hydraulic Brake- 6×4 Dump Truck

9


System Layout
Full Air Brake - 6×4 Tractor

10


System Layout
Location

Pressure Control Valve for Front (A.O.H)

11


System Layout

12

Location

Pressure Control Valve for Rear brake


System Layout

13

Location

Wheel speed sensor - Front

Wheel speed sensor - Rear


Components Description

14

ABS Control Module

Cab Mounted

Frame Mounted

The ECM is the brain of the ABS system.
It receives information from the sensors and sends signals to the ABS valves.
ECM is installed at the underneath the seat of the passenger side.


Components Description

15

ABS Control Module Connector

7
8

9
10
11
12
13
14
16
17
18

Main power supply
Main power supply
Main power supply
Ground
Ground
Ground
Self diagnosis
“K”terminal
Self diagnosis
“L”terminal
ASR Warning lamp
DBR Relay
ABS Warning

1.FRT/LH Pressure
modulator valve
outlet
2.FRT/LH Pressure
modulator valve inlet
3.FRT/LH Pressure

modulator ground
4.FRT/LH Wheel
speed sensor
5.FRT/LH Wheel
speed sensor

4.FRT/RH Wheel
speed sensor
5.FRT/RH Wheel
speed sensor
7.FRT/RH Pressure
modulator valve
outlet
8.FRT/RH Pressure
modulator valve
inlet
9.FRT/RH Pressure
modulator valve
ground

1.RR/LH Pressure modulator
valve outlet
2.RR/LH Pressure modulator
valve inlet
3.RR/LH Pressure modulator
valve ground
4.ASR Ground
5.RR/LH Wheel speed sensor
6.RR/LH Wheel speed sensor
7.ASR Power supply

8.RR/RH Wheel speed sensor
9.RR/RH Wheel speed sensor
10.RR/RH Pressure modulator
valve outlet
11.RR/RH Pressure modulator
valve inlet
12.RR/RH Pressure modulator
valve ground


Components Description

16

Exercise : ABS Control Module : Service Advices
If you have vehicles with ABS ECU, how you handle it?
Discuss your service points in the group and make a note of the most important items

• Do not expose ABS ECU to splash-water, mud, dust or
mechanical stress such as drop down etc.
• Do not touch the electrical connectors with fingers or
parts other than the wiring harness plugs
• Never weld on a vehicle while ECUs are connected
• Never start the Engine other than the own battery as long
as ECUs are connected
• Never run the Engine without a securely connected battery
• Never open an ECU nor try to repair it


Components Description

Wheel Speed Sensor
Minimum output voltage : 0.75 V

17


Components Description

18

Exercise : WSS: service advice
When servicing wheel speed sensor , Discuss your service points in the group and make a note at
the point as the shown in the figure.
do not use force by tools for installing the sensor
connect securely and tight

use grease before assembly

avoid strong wire bends

use grease before assembly

Fix the wires securely in order to prevent chafe marks or other damages.


Components Description
Wheel Speed Sensor - Output Signal (Normal)

19

Components Description
Wheel Speed Sensor - Output Signal (Abnormal)

20


Components Description
Wheel Speed Sensor - Output Signal (abnormal)

21


Components Description

22

WSS: service advice
• The single WSS (removed from the vehicle) can simply be tested with a multi-meter by a resistance
(Ohm) measurement

0.9 ~ 2K Ohm

> 30k Ohm
to chassis
ground


Components Description

23

Pressure Control Valve
Outlet Port
(Delivery)

Resistance Check
Specification : 11 ~ 16.5 Ω
Pin 1 & 2, Pin 1 & 3
Inlet Port (supply)
Pin 1 (Green/Yellow)
Pin 2 (Blue)
Pin 3 (Brown)


Operational Principle
Pressure Increase Mode

24


Operational Principle
Pressure Hold Mode

25