Toyota Sequoia (2005). Manual - part 492

–

DIAGNOSTICS

BODY CONTROL SYSTEM

DI–1763

1957

3

Check wire harness and connector between each illumination light and body
ECU, each illumination light and back door ECU, each illumination light and bat-
tery (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

).

I24147

B7

HORN

HORN Relay

2

1

Body ECU

1

2D

18

HR

HORN

B5

B–Y

6

C9
Horn SW

B

5

4

F10 
FL Block

H8
Horn (low)

1

1

B

B

8

2H

7

2F

5

3

W–R

W–R

19

IA1

26

Battery

H7
Horn (high)

Engine Room J/B

B

DI–1764

–

DIAGNOSTICS

BODY CONTROL SYSTEM

1958

Horn circuit

CIRCUIT DESCRIPTION

The vehicle horn sounds when the horn switch is pressed. It also sounds as an alarm for the theft deterrent
system when the body ECU detects any alert condition.

WIRING DIAGRAM

DI94T–08

–

DIAGNOSTICS

BODY CONTROL SYSTEM

DI–1765

1959

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 vehicle horn 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

VEHICLE HORN

Turn vehicle horn sound ON/OFF

–

OK:

The horn sounds or stops correctly when operating it through the hand–held tester.

OK

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

DI–1686

).

NG

2

Check horn (See page 

BE–145

).

NG

Replace horn.

OK

3

Check horn switch (See page 

BE–145

).

NG

Replace horn switch.

OK

DI–1766

–

DIAGNOSTICS

BODY CONTROL SYSTEM

1960

4

Check horn relay (See page 

BE–145

).

NG

Replace horn relay.

OK

5

Check wire harness and connector between horn and body ECU, body ECU and
horn switch (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

).