Toyota Sequoia (2005). Manual - part 479

–

DIAGNOSTICS

BODY CONTROL SYSTEM

DI–1711

1905

INSPECTION PROCEDURE

1

Check FOG LIGHT relay (See page 

BE–34

).

NG

Replace FOG LIGHT relay.

OK

2

Check fog light switch (See page 

BE–34

).

NG

Replace fog light switch.

OK

3

Check wire harness and connector between FOG LIGHT relay and fog light
switch, FOG LIGHT relay and battery, FOG LIGHT relay and body ground 
(See page 

IN–35

).

NG

Repair or replace wire harness or connector.

OK

4

Check wire harness and connector between fog light switch and body ECU 
(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

).

DI–1712

–

DIAGNOSTICS

BODY CONTROL SYSTEM

1906

Daytime running light relay circuit

CIRCUIT DESCRIPTION

Power is supplied to the DIMMER and DRL No. 4 relays when the HEAD relay is turned on.
The HEAD relay turns on by turning the light control switch to the TAIL or HEAD position.
The DIMMER relay turns on by turning the headlight dimmer switch to the LOW, HIGH, or FLASH position.
The body ECU determines the light control switch position and turns on the DRL No. 4 and DIMMER relays.
The DRL No. 4 relay and the daytime running light resistor are parallel circuits. If the light control switch is
OFF, electric current flows to body ground via the resistor instead of driving the DRL No. 4 relay. The head-
lights come on and dim according to the amount of resistance.

DI6M3–11

I28771

3

2

2

1

2

Body ECU

2

2

L

1

G–W

2

2

2

Engine Room R/B No. 2

R–W

2

1

2

1

2

1

R–L

A

To Body ECU
(HEAD Relay Circuit)

B7

R

2F

B

5

ED

MAIN

HEAD Relay

DRL

IA1

17

Battery

F10
FL Block

J1
J/C

W–L

W–L

R–L

R–W

R–W

W–B

G–W

3

2

1

W–L

W

1

2

A

A

A

2

2

2

2

1

2

3

5

B7

W–B

R

W–B

R–L

L

L

5

3

2

1

5

3

1

2

1

2

1

2G

2C

2D

1

6

4

A

2

2

2

2

2

DIMMER Relay

Engine Room R/B No. 2

H5
Headlight
LH

16

17

C

H–LP RH

H–ON

DIM

DRL No. 4 Relay

J4
J/C

C

H6
Headlight RH

H–LP LH

H–LP RL

H–LP LL

IA1

18

W–B

4

Engine Room R/B No. 2

Engine Room J/B

6

LG–R

R–B

J2 J/C

W–L

D1 Daytime Running
Light Resistor

J5
J/C

A

EA

–

DIAGNOSTICS

BODY CONTROL SYSTEM

DI–1713

1907

WIRING DIAGRAM

DI–1714

–

DIAGNOSTICS

BODY CONTROL SYSTEM

1908

INSPECTION PROCEDURE

1

Check DRL No. 4 relay and DIMMER relay (See page 

BE–27

).

NG

Replace DRL No. 4 relay and DIMMER relay.

OK

2

Check wire harness and connector (Daytime running light circuit) 
(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

).