Toyota Sequoia (2005). Manual - part 239

F16805

S25

Suspension Control ECU 
Wire Harness View:

RC

F19460

Engine Room R/B No. 2:

AIR SUS 
Relay Terminal

–

DIAGNOSTICS

AIR SUSPENSION SYSTEM

DI–751

945

3

Check harness and connector (Engine room R/B – Suspension control ECU,
Body ground).

PREPARATION:
Disconnect the ECU connector.
CHECK:
Check for an open or short circuit in the harness and the con-
nector between the AIR SUS relay terminal 1 of the engine
room R/B and terminal S25–5 (RC) of the suspension control
ECU.
OK:

There is no open or short in the wire harness.

CHECK:
Check for an open circuit in the harness and the connector be-
tween the AIR SUS relay terminal 2 of the engine room R/B and
body ground.
OK:

There is no open in the wire harness.

NG

Repair or replace harness or connector.

OK

Replace suspension control ECU
(See page 

IN–35

).

DI–752

–

DIAGNOSTICS

AIR SUSPENSION SYSTEM

946

DTC

C1742/42 Height Control Compressor Circuit

CIRCUIT DESCRIPTION

When the ”UP” side of the height control is pressed, a signal is sent from terminal RC of the suspension con-
trol ECU to switch the AIR SUS relay ON. As a result, the relay contacts close and the compressor motor
turns on, producing compressed air.
The suspension control ECU detects the amount of current flow to the compressor motor by means of the
differences in potential at terminals RM+ and RM– of the suspension control ECU. In this way, the suspen-
sion control ECU monitors the compressor circuit for abnormalities.

DTC No.

DTC Detecting Condition

Trouble Area

C1742/42

With the AIR SUS relay activated, a lock, open or short signal

of the height control compressor motor is detected for 4 sec. or

more.

Height control compressor assy

Height control compressor circuit

Suspension control ECU

HINT:
Once the ECU stores DTC C1742/42 in the memory, the vehicle height control is not carried out until the
normal signal is input to the ECU from the compressor motor. However, the control automatically resumes
approx. 70 min. after the ignition switch is turned ON.

DIDDU–01

F19444

Height Control Compressor
(Compressor/Height Control Dryer)

H13

3

Engine Room R/B No. 2

W–B

Battery

J28
J/C

R–L

BM2

3

IN1

15

S25

20

2

3

2

5

1

W

9

B

5

J8
J/C

A

A

W–B

1K

12

1F

9

A

W–B

IE

Suspension
Control
ECU

RC

F10 
Fusible Link Block

AIR SUS

Instrument 
Panel J/B

RM+

R–L

R–L

H13

4

BR–Y

BM2

4

IA1

21

S25

21

BR–Y

BR–Y

RM–

AIR SUS Relay

H13

1

W

BM2

1

IC4

8

W

W

W

2

2

2

S25

5

G–Y

IN1

6

IA1

25

G–Y

BJ

H13

2

BM2

2

W–B

A

J19
J/C

W–B

ALT

–

DIAGNOSTICS

AIR SUSPENSION SYSTEM

DI–753

947

WIRING DIAGRAM

F19435

1 (+)

2 (–)

Connector Front View:

4

3

DI–754

–

DIAGNOSTICS

AIR SUSPENSION SYSTEM

948

INSPECTION PROCEDURE

1

Inspect height control compressor.

PREPARATION:
(a)

Disconnect the height control compressor connector.

(b)

Connect the positive (+) lead from the battery to terminal
1 and the negative (–) lead to terminal 2.

CHECK:
Apply battery voltage between terminals 1 and 2 of the height
control compressor.
OK:

Compressor motor operates.

NOTICE:

Do not operate the height control compressor assy
for 90 sec. or more.

Since a short and lock inside the height control com-
pressor assy causes enormous current to flow, stop
the operation immediately when it does not rotate.

CHECK:
Check continuity between each terminal of the height control
compressor.
OK:

Terminal No.

Specified condition

2 – 4

Continuity

3 – 4

Continuity

NG

Replace height control compressor
(See page 

SA–162

).

OK