Get INTRODUCTION -> How to Use the Diagnostic Chart and Inspection Procedure Guide for Toyota Avensis 4 Door First Generation (1997-2003)

IN–30

INTRODUCTION

–

HOW TO TROUBLESHOOTECU CONTROLLED

SYSTEMS

IN011–38

HOW TO USE THE DIAGNOSTIC

CHART AND INSPECTION

PROCEDURE

1.

CONNECTOR CONNECTION AND TERMINAL IN-

SPECTION

S

For troubleshooting, diagnostic trouble code charts or

problem symptom charts are provided for each circuit with

detailed inspection procedures on the following pages.

When all the component parts, wire harnesses and con-

nectors of each circuit except the ECU are found to be

normal in troubleshooting, then it is determined that the

problem is in the ECU. Accordingly, if diagnosis is per-

formed without the problem symptoms occurring, refer to

Step 8 to replace the ECU. So always confirm that the

problem symptoms are occurring, or proceed with inspec-

tion while using the symptom simulation method.

The instructions ”Check wire harness and connector” and

”Check and replace ECU” which appear in the inspection

procedure, are common and applicable to all diagnostic

trouble codes. Follow the procedure outlined below

whenever these instructions appear.

FI0046

FI0047

FI0048

S

OPEN CIRCUIT:

This could be due to a disconnected wire harness, faulty con-

tact in the connector, and a connector terminal pulled out, etc.

HINT:

S

It is rarely the case that a wire is broken in the middle of

it. Most cases occur at the connector. In particular, care-

fully check the connectors of sensors and actuators

Faulty contact could be due to rusting of the connector

terminals, to foreign materials entering terminals or a de-

formation of connector terminals. Simply disconnecting

and reconnecting the connectors once changes the

condition of the connection and may result in a return to

normal operation. Therefore, in troubleshooting, if no ab-

normality is found in the wire harness and connector

check, but the problem disappears after the check, then

the cause is considered to be in the wire harness or con-

nectors.

S

SHORT CIRCUIT:

This could be due to a contact between wire harness and the

body ground or to a short circuit occurred inside the switch, etc.

HINT:

When there is a short between the wire harness and body

ground, check thoroughly whether the wire harness is caught

in the body or is clamped properly.

AVENSIS/CORONA SUP (RM781E)

IN–31

INTRODUCTION

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HOW TO TROUBLESHOOTECU CONTROLLED

SYSTEMS

2.

CONNECTOR HANDLING

When inserting tester probes into a connector, insert them from

the rear of the connector. When necessary, use mini test leads.

For water resistant connectors which cannot be accessed from

behind, take good care not to deform the connector terminals.

FI7187

IN0379

IN0378

IN0380

3.

CONTINUITY CHECK (OPEN CIRCUIT CHECK)

Sensor Side

ECU Side

(a) Disconnect the connectors at both ECU and sensor

sides.

(b) Measure the resistance between the applicable terminals

of the connectors.

Resistance: 1 Ω or less

HINT:

Measure the resistance while lightly shaking the wire harness

vertically and horizontally.

ECU Side

Sensor Side

4.

RESISTANCE CHECK (SHORT CIRCUIT CHECK)

ECU Side

(a) Disconnect the connectors on both ends.

(b) Measure the resistance between the applicable terminals

of the connectors and body ground. Be sure to carry out

this check on the connectors on both ends.

Resistance: 1 MΩ or higher

Sensor Side

HINT:

Measure the resistance while lightly shaking the wire harness

vertically and horizontally.

5.

VISUAL CHECK AND CONTACT PRESSURE CHECK

(a) Disconnect the connectors at both ends.

(b) Check for rust or foreign material, etc. in the terminals of

the connectors.

(c) Check crimped portions for looseness or damage and

check that the terminals are secured in lock portion.

HINT:

Pull Lightly

Looseness of Crimping

The terminals should not come out when pulled lightly from the

back.

IN0381

AVENSIS/CORONA SUP (RM781E)

IN–32

INTRODUCTION

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HOW TO TROUBLESHOOTECU CONTROLLED

SYSTEMS

(d) Prepare a test male terminal and insert it in the female ter-

minal, then pull it out.

NOTICE:

When testing a gold–plated female terminal, always use a

gold–plated male terminal.

HINT:

When the test terminal is pulled out more easily than others,

there may be poor contact in that section.

6.

CHECK OPEN CIRCUIT

Fig. 1

ECU

For the open circuit in the wire harness in Fig. 1, perform ”(a)

Continuity Check” or ”(b) Voltage Check” to locate the section.

C

OPEN

B

A

1

2

Sensor

1

2

1

2

1

2

Z17004

(a) Check the continuity.

Fig. 2

(1) Disconnect connectors ”A” and ”C” and measure

the resistance between them.

ECU

In the case of Fig. 2:

A

C

1

2

B

Between terminal 1 of connector ”A” and terminal 1

of connector ”C” → No continuity (open)

Between terminal 2 of connector ”A” and terminal 2

of connector ”C” → Continuity

Sensor

1

2

1

2

Therefore, it is found out that there is an open circuit

between terminal 1 of connector ”A” and terminal 1

of connector ”C”.

Z17005

Fig. 3

(2) Disconnect connector ”B” and measure the resis-

tance between the connectors.

ECU

In the case of Fig. 3:

Between terminal 1 of connector ”A” and terminal 1

of connector ”B1” → Continuity

Between terminal 1 of connector ”B2” and terminal

1 of connector ”C” → No continuity (open)

Therefore, it is found out that there is an open circuit

between terminal 1 of connector ”B2” and terminal

1 of connector ”C”.

Sensor

B2

C

1

2

B1

A

1

2

1

2

1

2

B04722

AVENSIS/CORONA SUP (RM781E)

IN–33

INTRODUCTION

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HOW TO TROUBLESHOOTECU CONTROLLED

SYSTEMS

(b) Check the voltage.

Fig. 4

In a circuit in which voltage is applied (to the ECU connec-

tor terminal), an open circuit can be checked for by con-

ducting a voltage check.

5V

A

0V

C

Sensor

As shown in Fig. 4, with each connector still con-

nected, measure the voltage between body ground

and terminal 1 of connector ”A” at the ECU 5V out-

put terminal, terminal 1 of connector ”B”, and termi-

nal 1 of connector ”C”, in that order.

5V

B

5V

1

2

Z17007

If the results are:

5V: Between Terminal 1 of connector ”A” and Body Ground

5V: Between Terminal 1 of connector ”B” and Body Ground

0V: Between Terminal 1 of connector ”C” and Body Ground

Then it is found out that there is an open circuit in the wire har-

ness between terminal 1 of ”B” and terminal 1 of ”C”.

7.

CHECK SHORT CIRCUIT

Fig. 5

If the wire harness is ground shorted as in Fig. 5, locate the sec-

tion by conducting a ”continuity check with ground”.

C

1

2

SHORT

B

1

2

A

1

2

Z17008

Check the continuity with ground.

Fig. 6

(1) Disconnect connectors ”A” and ”C” and measure

the resistance between terminal 1 and 2 of connec-

tor ”A” and body ground.

ECU

B

C

1

2

A

1

2

In the case of Fig. 6:

Between terminal 1 of connector ”A” and body

ground → Continuity (short)

Sensor

1

2

Between terminal 2 of connector ”A” and body

ground → No continuity

Z17009

Therefore, it is found out that there is a short circuit

between terminal 1 of connector ”A” and terminal 1

of connector ”C”.

AVENSIS/CORONA SUP (RM781E)

IN–34

INTRODUCTION

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HOW TO TROUBLESHOOTECU CONTROLLED

SYSTEMS

(2) Disconnect connector ”B” and measure the resis-

tance between terminal 1 of connector ”A” and body

ground, and terminal 1 of connector ”B2” and body

ground.

Fig. 7

ECU

In the case of Fig. 7:

Between terminal 1 of connector ”A” and body

ground → No continuity

B2

1

2

C

1

2

B1

1

2

A

1

2

Sensor

Between terminal 1 of connector ”B2” and body

ground → Continuity (short)

Z17808

Therefore, it is found out that there is a short circuit

between terminal 1 of connector ”B2” and terminal

1 of connector ”C”.

8.

CHECK AND REPLACE ECU

First check the ECU ground circuit. If it is faulty, repair it. If it is

normal, the ECU could be faulty, so replace the ECU with a nor-

mal functioning one and check that the symptoms appear.

(1) Measure the resistance between the ECU ground

terminal and the body ground.

Resistance: 1 Ω or less

Example

Ground

IN0383

(2) Disconnect the ECU connector, check the ground

terminals on the ECU side and the wire harness

side for bend and check the contact pressure.

ECU Side

Ground

W/H Side

Ground

IN0384

AVENSIS/CORONA SUP (RM781E)

INTRODUCTION -> How to Use the Diagnostic Chart and Inspection Procedure for Your Toyota Avensis 4 Door First Generation (1997-2003)

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