Toyota Sequoia (2005). Manual - part 240

F16805

Suspension Control ECU 
Wire Harness View:

S25

RM+

RM–

F19461

Height Control Compressor
Connector Front View:

H13

–

DIAGNOSTICS

AIR SUSPENSION SYSTEM

DI–755

949

2

Check harness and connector (height control compressor – Suspension control
ECU).

PREPARATION:
Disconnect the ECU connector.
CHECK:
Check for an open or short circuit in the harness and the con-
nector between terminals 3 and 4 of the height control compres-
sor and terminals S25–20 (RM+) and S25–21 (RM–) of the sus-
pension control ECU.
OK:

There is no open or short in the wire harness.

NG

Repair or replace harness or connector.

OK

F19461

Height Control Compressor
Connector Front View:

H13

DI–756

–

DIAGNOSTICS

AIR SUSPENSION SYSTEM

950

3

Check harness and connector (Height control compressor – Battery, Body
ground).

PREPARATION:
(a)

Reconnect the ECU connector.

(b)

Turn the ignition switch ON.

CHECK:
Measure the voltage according to the value(s) in the table be-
low.
OK:

Tester connection

Condition

Specified value

H13–1 – Body ground

Engine idling, height con-

trol switch is pushed from

”N” to ”UP”

10 to 14

 

V

HINT:
Measure the voltage within 90 seconds.
CHECK:
Measure the resistance according to the value(s) in the table
below.
OK:

Tester connection

Condition

Specified value

H13–2 – Body ground

Always

Below 1 

Ω

NG

Repair or replace harness or connector.

OK

Replace suspension control ECU
(See page 

IN–35

).

–

DIAGNOSTICS

AIR SUSPENSION SYSTEM

DI–757

951

DTC

C1751/51 Continuous Electric Current To Height Con-

trol Compressor

CIRCUIT DESCRIPTION

DTC No.

DTC Detecting Condition

Trouble Area

C1751/51*

1

With the AIR SUS relay activated, the vehicle does not go up
to the standard vehicle height after the 90 sec. have elapsed.

Height control compressor assy

Height control compressor circuit

Height control sensor circuit

Height control sensor sub–assy

Relief valve

AIR SUS relay circuit

Air leakage from the air tube or each valve

Clogging in the air tube or each valve

Suspension control ECU

*

1

: The compressor motor operates continuously to raise vehicle height and allows electric current flow to

the AIR SUS relay for 90 seconds or more under the following conditions:

Vehicle height control is attempted on a steep slope when the vehicle is overloaded.

The compressor remains on for an excessive period of time or repeatedly turns on and off because
of continuous height control switch operation.

If the compressor remains on because the vehicle is jacked up, the vehicle height is set at a position
lower than normal while the engine is running and then the vehicle height control function raises the
vehicle.

Thus DTC C1751/51 may be output and vehicle height control may be suspended. (This is not electrically
abnormal.) In this case, however, the vehicle height operation is resumed approx. 10 min. after the ignition
switch is turned ON after the ECU detects the first error. If ECU detects another error, it takes 70 minutes
until control is resumed.

WIRING DIAGRAM

See page 

DI–752

.

DIDDV–01

DI–758

–

DIAGNOSTICS

AIR SUSPENSION SYSTEM

952

INSPECTION PROCEDURE

1

Inspect height control compressor circuit (See page 

DI–752

).

NEXT

2

Inspect air leakage (See page 

SA–156

).

CHECK:
Check tube connections for air leakage.
OK:

No leaks

NG

Repair or replace air tube.

OK