Toyota Sequoia (2005). Manual - part 478

–

DIAGNOSTICS

BODY CONTROL SYSTEM

DI–1707

1901

INSPECTION PROCEDURE

HINT:
When using the hand–held tester, start the inspection from step 1 and when not using the hand–held tester,
start from step 2.

1

Check TAILLIGHT relay using hand–held tester.

PREPARATION:
(a)

Connect the hand–held tester to the DLC3.

(b)

Turn the ignition switch ON.

CHECK:
According to the display on the tester, perform the ”ACTIVE TEST”.
BODY ECU:

Item

Test Details

Diagnostic Note

TAIL LIGHT

Taillight ON/OFF

–

OK:

The taillights turn on or off correctly when operating them through the hand–held tester.

OK

Proceed to next circuit inspection shown in
problem symptoms table (See page 

DI–1686

).

NG

2

Check TAILLIGHT relay (See page 

BE–27

).

NG

Replace TAILLIGHT relay.

OK

3

Check wire harness and connector between TAILLIGHT relay and body ECU, bat-
tery and TAILLIGHT relay (See page 

IN–35

).

NG

Repair or replace wire harness or connector.

OK

Proceed to next circuit inspection shown in
problem symptoms table 
(See page 

DI–1686

).

I24144

Body ECU

MAIN

Engine Room J/B

HEAD Relay

Instrument Panel J/B

Battery

LG–R

2D

B

1

2F

L

R–W

1

2

5

3

2F

2G

2C

B7

1G

1J

L

R–L

R–L

HRLY

8

6

1

6

1

2

(*1): w/ Daytime Running Light
(*2): w/o Daytime Running Light

LG–R

6

9

8

To Headlight RH

To Headlight LH

To DRL No.4 Relay

To DIMMER Relay

To DIMMER Relay

B

4

5

F10
FL Block

(*2)

(*2)

(*1)

(*1)

(*1)

H–LP RH (*2)

DRL (*1)

H–LP LH (*2)

(*1)

DI–1708

–

DIAGNOSTICS

BODY CONTROL SYSTEM

1902

Headlight Relay Circuit

CIRCUIT DESCRIPTION

HEAD relay will be ”ON” by operating the light control switch. The transistor which activates the HEAD relay
has two sorts: one is activated by the light control switch for fail safe and the other is activated by CPU. The
one that is activated by CPU prevents the headlight from turning off at the time of trouble with the other sys-
tem in the automatic operation circuit.
When the theft deterrent system is activated, it causes the transistor in the ECU to switch ON and OFF at
approximately 0.25 sec. intervals. This switches the HEAD relay ON and OFF, and thus flashing the head-
lights (See the wiring diagram below).
In this condition, if any of the following operations is done, the transistor in the ECU goes OFF and the HEAD
control relay switches OFF, and thus stopping the headlights flashing:

(1)

Unlock the front LH or RH door with a key.

(2)

Turn the ignition switch to ACC or ON position.

(3)

Unlock the doors with the wireless door lock control system.

(4)

Wait for approximately 60 seconds.

WIRING DIAGRAM

DI5VQ–14

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DIAGNOSTICS

BODY CONTROL SYSTEM

DI–1709

1903

INSPECTION PROCEDURE

HINT:
When using the hand–held tester, start the inspection from step 1 and when not using the hand–held tester,
start from step 2.

1

Check HEAD relay using hand–held tester.

PREPARATION:
(a)

Connect the hand–held tester to the DLC3.

(b)

Turn the ignition switch ON.

CHECK:
According to the display on the tester, perform the ”ACTIVE TEST”.
BODY ECU:

Item

Test Details

Diagnostic Note

HEAD LIGHT

Headlight relay ON/OFF

–

OK:

The headlights turn on or off correctly when operating them through the hand–held tester.

OK

Proceed to next circuit inspection shown in
problem symptoms table (See page 

DI–1686

).

NG

2

Check HEAD relay (See page 

BE–27

).

NG

Replace HEAD relay.

OK

3

Check wire harness and connector between HEAD relay and body ECU, battery
and HEAD relay (See page 

IN–35

).

NG

Repair or replace wire harness or connector.

OK

Proceed to next circuit inspection shown in
problem symptoms table 
(See page 

DI–1686

).

I28516

J5
J/C

Body ECU

FFOG

J50
J/C

J3
J/C

5

Instrument Panel J/B

From DIMMER Relay (*1)

FOG LIGHT Relay

FOG

1K

7

1B

9

1J

10

1L

1

3

1

2

D

D

D

1

2

F2
Front Fog
Light RH

W–B

B

1

2

P

W–B

ED

IG

ALT

F10
FL Block

8

5

B

Battery

R–W

C8 Combination Switch

 Fog Light Switch

B6

13

G–B

10

LFG

BFG

11

P

F1
Front Fog
Light LH

G–W (*1)
Y–R (*2)

W

P

A

(*1): w/ Daytime Running Light
(*2): w/o Daytime Running Light

B

J2
J/C

B

B

W–B

J18
J/C

W–B

W–B

IL1

From Headlight (*2)

16

A

DI–1710

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DIAGNOSTICS

BODY CONTROL SYSTEM

1904

Front fog light relay and switch circuit

CIRCUIT DESCRIPTION

The fog light switch is built into the combination switch.
Turning the fog light switch ON supplies power to terminal FFOG of the body ECU.
The fog lights come on when the FOG light relay is turned on.

WIRING DIAGRAM

DI6U4–14