Toyota Sequoia (2005). Manual - part 10

 

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Toyota Sequoia (2005). Manual - part 10

 

 

Z17004

Fig. 1

OPEN

ECU

2

Sensor

2

2

2

1

1

1

1

A

B

C

Z17005

Fig. 2

ECU

Sensor

2

1

A

B

C

1

1

2

2

B04722

Fig. 3

ECU

Sensor

2

1

A

B1

C

1

1

2

2

1

2

B2

INTRODUCTION

HOW TO TROUBLESHOOT ECU CONTROLLED 
SYSTEMS

IN–37

37

(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

For an open circuit in the wire harness in Fig. 1, perform ”(a)
Continuity Check” or ”(b) Voltage Check” to locate the section.

(a)

Check the continuity.
(1)

Disconnect connectors ”A” and ”C” and measure
the resistance between them.
In the case of Fig. 2:
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

Therefore, it is found out that there is an open circuit
between terminal 1 of connector ”A” and terminal 1
of connector ”C”.

(2)

Disconnect connector ”B” and measure the resis-
tance between the connectors.
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”.

Z17007

Fig. 4

Sensor

2

1

A

C

1

1

2

2

B

5V

5V

5V

0V

Z17008

Fig. 5

2

1

A

C

1

1

2

2

B

SHORT

Z17009

Fig. 6

2

1

A

C

1

1

2

2

B

Sensor

ECU

IN–38

INTRODUCTION

HOW TO TROUBLESHOOT ECU CONTROLLED 
SYSTEMS

38

(b)

Check the voltage.
In a circuit in which voltage is applied (to the ECU connec-
tor terminal), an open circuit can be checked by conduct-
ing a voltage check.

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.

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

If the wire harness is shorted as in Fig. 5, locate the section by
conducting a ”continuity check with ground”.

Check the continuity with ground.

(1)

Disconnect connectors ”A” and ”C” and measure
the resistance between terminals 1 and 2 of con-
nector ”A” and body ground.
In the case of Fig. 6:
Between terminal 1 of connector ”A” and body
ground 

 Continuity (short)

Between terminal 2 of connector ”A” and body
ground 

 No continuity

Therefore, it is found out that there is a short circuit
between terminal 1 of connector ”A” and terminal 1
of connector ”C”.

Z17808

Fig. 7

Sensor

2

1

A

B1

C

1

1

2

2

1

2

B2

ECU

IN0383

Example

Ground

IN0384

Ground

Ground

ECU Side

W/H Side

INTRODUCTION

HOW TO TROUBLESHOOT ECU CONTROLLED 
SYSTEMS

IN–39

39

(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.
In the case of Fig. 7:
Between terminal 1 of connector ”A” and body
ground 

 No continuity

Between terminal 1 of connector ”B2” and body
ground 

 Continuity (short)

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 

 or less

(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.

IN04Q–33

IN–40

INTRODUCTION

TERMS

40

TERMS

ABBREVIATIONS USED IN THIS MANUAL

Abbreviations

Meaning

ABS

Anti–Lock Brake System

A/C

Air Conditioner

AC

Alternating Current

ACC

Accessory

ACIS

Acoustic Control Induction System

ACM

Active Control Engine Mount

ACSD

Automatic Cold Start Device

A.D.D.

Automatic Disconnecting Differential

A/F

Air–Fuel Ratio

AHC

Active Height Control Suspension

ALR

Automatic Locking Retractor

ALT

Alternator

AMP

Amplifier

ANT

Antenna

APPROX.

Approximately

ASSY

Assembly

A/T, ATM

Automatic Transmission (Transaxle)

ATF

Automatic Transmission Fluid

AUTO

Automatic

AUX

Auxiliary

AVG

Average

AVS

Adaptive Variable Suspension

B+

Battery Voltage

BA

Brake Assist

BACS

Boost Altitude Compensation System

BAT

Battery

BDC

Bottom Dead Center

B/L

Bi–Level

B/S

Bore–Stroke Ratio

BTDC

Before Top Dead Center

BVSV

Bimetallic Vacuum Switching Valve

CB

Circuit  Breaker

CCo

Catalytic Converter For Oxidation

CCV

Canister Closed Valve

CD

Compact Disc

CF

Cornering Force

CG

Center Of Gravity

CH

Channel

CKD

Complete Knock Down

COMB.

Combination

CPE

Coupe

CPS

Combustion Pressure Sensor

CPU

Central Processing Unit

CRS

Child Restraint System

CTR

Center

C/V

Check Valve

CV

Control Valve

CW

Curb Weight

 

 

 

 

 

 

 

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