Toyota training body electrical diagnosis intro

BODY ELECTRICAL DIAGNOSIS
Course 652 Technician Handbook

© 2010 Toyota Motor Sales, U.S.A., Inc.

TOYOTA Technical Training

All rights reserved. This book may not be reproduced or copied, in whole or in part by any means, without the written permission of
Toyota Motor Sales, U.S.A., Inc.
Revision Date: April 12, 2010



Table of Contents
652 Body Electrical Diagnosis
Objectives

Final Student Performances ..................................................................a

Body Electrical
Diagnosis

Course Menu ..........................................................................................3

Section 1:
Electrical
Circuit Theory

Topics .....................................................................................................5
Automotive Electrical Circuits .................................................................7
Load....................................................................................................8

Voltage Sources .................................................................................9
Other Voltage Sources .....................................................................10
Over-current Protection Devices.......................................................11
Control Devices ................................................................................12
Conductors .......................................................................................13
Connectors .......................................................................................14
Circuit Operation...............................................................................15
Principles of Electricity ..........................................................................16
Voltage..............................................................................................16
Voltage Measurements.....................................................................17
Available Voltage ..............................................................................17
Open Circuit Voltage.........................................................................18
Voltage Drop.....................................................................................19
Measuring Voltage Drop ...............................................................20
Understanding Voltage Drops.......................................................20
Current ..............................................................................................25
Measuring Amperage ...................................................................26
Power............................................................................................27
Resistance ........................................................................................28
Measuring Resistance ......................................................................29
Basic Circuit Principles .........................................................................30
Series Resistance.............................................................................30
Parallel Resistance ...........................................................................31
Series-Parallel Resistance................................................................32
Why Does it Matter? .....................................................................32
Ohm’s Law ............................................................................................33
Applying Ohm’s Law .........................................................................34
General Electrical Rules ...................................................................35
Series Circuit Principles ........................................................................36
Voltage..............................................................................................36

Resistance and Current ....................................................................37
Series Circuit General Rules ............................................................37
Parallel Circuit Principles ......................................................................42
Voltage..............................................................................................43
Backprobing a Connector .............................................................44
Resistance ........................................................................................45
Current .............................................................................................46
Parallel Circuit General Rules ..........................................................46

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652 Body Electrical Diagnosis
Section 2:
Using the
Electrical Wiring
Diagram

ii

Topics ...................................................................................................47
The Electrical Wiring Diagram ..............................................................48
EWD Overview......................................................................................49
The Index..........................................................................................49
System Circuits Index .......................................................................50
EWD on TIS – 2005 MY and Earlier .................................................51
EWD on TIS – 2006 MY and Later ...................................................52

“How to Use This Manual” ................................................................53
Troubleshooting Section ...................................................................55
Connector Repair Information ..........................................................56
Glossary of Terms and Symbols.......................................................57
Switch Positions................................................................................58
Tracing Current Flow ........................................................................59
Abbreviated Illustrations ...................................................................60
Gang-type Switches..........................................................................61
Relays ...............................................................................................63
Solid State Relays ............................................................................64
Reading the System Circuit Diagram....................................................65
System Outline .................................................................................66
Service Hints.....................................................................................66
Important Notes ................................................................................67
Wire Identification .............................................................................68
Painted Wire Harnesses ...................................................................69
Shielding ...........................................................................................70
Components and Connectors ...............................................................71
Component Locations.......................................................................71
Component Connectors....................................................................72
Connector List...................................................................................72
Multiple Component Connectors ......................................................73
Part Number of Connectors ..............................................................74
Pin Numbering ..................................................................................75
Color Coding.....................................................................................75
Junction Blocks and Relay Blocks ........................................................76
Junction Blocks.................................................................................76
Junction Block Location ....................................................................77
J/B Inner Circuit ................................................................................78
Relay Blocks .....................................................................................79

Junction Connectors, Harness Connectors and Splice Points .............80
Junction Connectors .........................................................................80
Junction Connector Connectors .......................................................81
Wire Harness Connectors.................................................................83
Harness Connector Identification......................................................84
Splice Points .....................................................................................85
Power Source Diagrams .......................................................................86
Power Source System Diagram........................................................86
Power Source (Current Flow Chart) .................................................87
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652 Body Electrical Diagnosis
Ground Points .......................................................................................88
Shared Ground Points ......................................................................89
Overall Wiring Diagram.........................................................................90
Finding System Circuit Diagrams on TIS..........................................92
Finding Other Resources..................................................................92
TIS Diagrams through the 2005 MY .................................................93
2006 MY Changes to EWD...................................................................94
Using the EWD Viewer .....................................................................95
Help Tab ...........................................................................................96
Finding System Circuit Diagrams in the EWD Viewer ......................97
System Circuit Diagrams ..................................................................98
System Outline .................................................................................99
System Hints.....................................................................................99
Components Location Using EWD Viewer .....................................100
Component Connectors in the EWD Viewer...................................101
Junction Block Location in the EWD Viewer...................................102

J/B Inner Circuit Using EWD Viewer...............................................103
Harness Connectors in EWD Viewer..............................................104
Splice Information for 2006 MY and Later ......................................107
Power Source System Diagram in EWD Viewer ............................108
Power Source Tab in EWD Viewer.................................................109
Ground Points in EWD Viewer........................................................110
Shared Ground Points in EWD Viewer ...........................................111
Finding Additional Information ...........................................................112
Other Sources of Information .........................................................115
Section 3:
Electrical
Diagnostic
Tools

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Topics .................................................................................................117
Introduction .........................................................................................118
Visual Inspection.................................................................................118
Operate the Circuit Thoroughly.......................................................118
Checking Connectors & Terminals .................................................119
Excessive Terminal Spread ........................................................120
Wire Harness Inspection.................................................................121
Visual Inspection Hints ...............................................................121
Jumper Wires..................................................................................122
Digital Multimeters ..............................................................................123
Additional Meter Features...............................................................123
Digital Voltmeters................................................................................124
Measuring Pin Voltage....................................................................124
Why a Good DVOM is Safe ............................................................124

Voltage Drop Measurement............................................................125
Available Voltage Measurement .....................................................130
Measuring Voltage Drop by Subtraction .........................................131
Digital Ammeter ..................................................................................134
Series Type Ammeter .....................................................................135
Clamp Type (Inductive Ammeter) ...................................................136
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Digital Ohmmeter ................................................................................137
Ohmmeter Common Mistakes ........................................................137
Audible Continuity Beep .................................................................138
Diode Check ...................................................................................139

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Section 4:
6-Step
Diagnostic
Process

Topics .................................................................................................141
Introduction .........................................................................................142
6-Step Diagnostic Process .................................................................142
Step #1 – Verify the Complaint ...........................................................143
Identify the Problem........................................................................143
Does a Problem Exist? ...................................................................143
Intermittent or Continuous? ............................................................144

Step #2 – Determine the Related Symptoms .....................................145
Perform a Thorough Operational Check.........................................145
How a Circuit is Related ................................................................146
How Much of the Circuit is Affected? .............................................146
Circuits with Self-Diagnosis ............................................................147
Step #3 – Analyze the Symptoms.......................................................148
If Entire Circuit is Inoperative..........................................................149
If Any Part of the Circuit Works.......................................................150
Eliminate Parts of the Circuit ..........................................................150
Trace the Paths of Current Flow.....................................................151
Step #4 – Isolate the Problem ............................................................152
Finding Possible Problem Areas.........................................................153
Where to Begin ...............................................................................153
The Split-Half Method .....................................................................154
Step #5 – Correct the Trouble ............................................................155
Component Service Hints ...............................................................155
Step #6 – Check for Proper Operation ...............................................156

Section 5:
Diagnosing
Body Electrical
Problems

Topics .................................................................................................159
Introduction .........................................................................................160
Diagnosing Open Circuit Problems.....................................................160
Using a Voltmeter on Open Circuit Problems .................................161
High Resistance Problems .................................................................168
Causes of a High Resistance Problem ...........................................168
Diagnosing High Resistance Problems ..........................................169

Determine if There is Current Flow in the Circuit........................169
Isolating a High Resistance Problem..............................................170
Parasitic Load .....................................................................................178
How to Measure Parasitic Load......................................................179
Diagnosing Parasitic Load ..............................................................181
Disconnecting Components ................................................................182
Procedure for Mapping Current Flow Through the J/Bs .................183
Diagnosing Shorts to Grounds............................................................184
Inspect the Fuse .............................................................................184
Short to Ground Diagnostic Strategy ..............................................184
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Selecting a Load .............................................................................185
Using a Headlamp as a Load .........................................................185
Intermittent or Continuous? ............................................................186
Disconnecting Component Connectors ..........................................186
Feedback Problems ............................................................................194
Diagnosing a Feedback Problem....................................................194
Quick Checks for Lighting Circuits..................................................195
Quick Checks for General Feedback Problems..............................195
If the Quick Checks Do Not Find the Cause ...................................196
Appendix

EWD Section H: How to Use This Manual.......................................... A-1

Worksheets

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Objectives
652 Body Electrical Diagnosis
Course 652 Body Electrical Diagnosis
Final Student Performances
Terminal Objective (Terminal FSP)
Given a vehicle with any of the conditions listed below, the appropriate tools & equipment,
and access to the vehicle’s EWD, the technician will be able to use the six-step diagnostic
process to identify the type of fault and its location, and explain/demonstrate the correct
repair procedure.
• Short-to-ground
• Open in a non-MPX circuit
• High resistance in a non-MPX circuit
• Feedback Problem
Technician Objectives (FSPs)
1. Given a 2010 Camry "Back-up Light System Circuit" the technician will be able to predict

voltage, amperage, and resistance values at various location on the diagram under a
variety of conditions (both normal and abnormal operation) and based upon the principals
outlined below:
Series Circuits
•

When there is only one load in the circuit, all the voltage is used up in that load

•

When there are multiple loads in the circuit, voltage is divided according to the
resistance of the loads. The load with the most resistance will use the most voltage;
the load with the least resistance will use the least voltage; The voltage used is
directly proportional to the resistance

•

Amperage is the same throughout the circuit. This means that an ammeter can be
connected anywhere in the circuit and measure the amperage

•

Total resistance is the sum of all the resistance in the circuit. Adding a resistance in
series will increase the total resistance and decrease current (amperage)

Parallel Circuits
•

The voltage applied to each branch of a parallel circuit is the same.

•

The current in a branch is determined by the branch's resistance. The branch with
the least resistance will have the most current.

•

Total resistance decreases as branches are added. Adding a branch lowers the total
resistance and increases current. The total circuit resistance is always lower than
the lowest branch resistance

Series-Parallel Circuits
•

Problems in the series portion of a series-parallel circuit affect the entire circuit.
Problems in a parallel branch of a series parallel circuit affect only the branch where
the problem is located

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Objectives
652 Body Electrical Diagnosis
2. Given access to the EWD, technician will be able to demonstrate his knowledge of what’s
available in the EWD by locating the following sections and features (paper version and
on TIS EWD Viewer):
•

Locate assigned System Circuit Diagrams in the EWD

•

Identify each of the symbols used on the system diagram, wire color. wire
identification, and pin number location

•

Locate, How to use the Manual; Abbreviations; Glossary of Terms & Symbols: Relay
Locations & JB Inner Circuit Diagram; Relay Blocks; Connector List; Part Numbers
of Connectors; Overall Electrical Wiring Diagram; and support sections, System
Outline & Service Hints

•

Locate components, ground points, connectors, junction blocks, harness to harness
connectors; switches; relays; splice points; in the manual and on the vehicle

•

Power source section and ground point section and describe how each is used when
diagnosing a problem

3. Given a 2010 Camry Remote Control Mirror System Circuit Diagram and a Radiator &
Condenser Fan System Circuit Diagram the technician will be able to:
•

Apply basic current flow theory to the diagram by tracing the path of current flow
through the circuit from B+ to ground

•

Configure the switches/relays in the circuit to the appropriate positions for the
operating conditions described

•

Identify the symbols used on the system circuit diagram

•

Predict voltage, amperage, and resistance values at various locations on the
diagram under a variety of conditions (normal and abnormal operation)

4. Given a DVOM with an inductive clamp and a simple System Circuit Diagram, the
technician will be able to demonstrate how to:

b

•

Make resistance, current measurements

•

Measure open circuit voltage, available voltage and voltage drop.

•

Properly identify a parasitic load in a circuit

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Objectives
652 Body Electrical Diagnosis
5. Given 8 different customer concerns (4 with full class participation and 4 in teams of two),
all of the appropriate tools and equipment, a vehicle(s) with select “faults” installed, and
access to the vehicle’s EWD, the technician will be able to demonstrate his ability to apply
the Six-step Diagnostic Process to:
•

•

•

•

•

Verify the customer concern by:
-

Duplicating the problem the Customer is describing

-

Identifying what circuit is involved in the concern

-

Locating information related to what is normal operation and customized settings
for that circuit

-

Determining if it is a problem, a normal operating condition or a customized
setting

-

Identifying the conditions under which the problem occurs

Determine the related symptoms by:
-

Identifying how much of the circuit is affected

-

Identifying related circuits and determining if problems exist in those circuits

-

Determining if DTCs are present

Analyze the problem by:
-

Defining exactly which components/circuits are affected based on both the
customer's concern and any related symptoms

-

Defining what kind of problem to look for (open, short-to-ground, high resistance,
feedback)

-

Identifying when the problem occurs (what operating conditions: key ON, driver's
door open, etc.)

-

Identifying on the wiring diagram where the problem could possibly be located

-

Determining what tests to perform first, what tools to use, and what results to
expect

-

Determining the easiest place to begin making the checks (split half method)

Isolate the problem by:
-

Performing initial tests

-

Determining the logical place to test next and predicting the expected results for
a normally operating circuit

Identify and describe the correct repair for the problem, such as:
-

Replacing a wire harness

-

Performing a proper repair to wiring, connections, connectors, or terminals

-

Replacing a component

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Objectives
652 Body Electrical Diagnosis
•

d

Describe the proper verification of the repair by:
-

Confirming the problem has been eliminated and that no new problems have
been created by the repair

-

Locating information regarding what initializations need to be performed following
the repair

-

Verifying all necessary initializations have been performed

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