SUSPENSION CONTROL: AIR SUSPENSION SYSTEM (w/o AVS): DESCRIPTION (2008 Sequoia)

Last Modified: 11-29-2007		1.6 C
Service Category: Suspension	Section: Suspension Control System
Model Year: 2008	Model: Sequoia	Doc ID: RM000001N96008X
Title: SUSPENSION CONTROL: AIR SUSPENSION SYSTEM (w/o AVS): DESCRIPTION (2008 Sequoia)

DTC

C1752

Height Control Compressor Motor Circuit Malfunction

DESCRIPTION

When the "UP" side of the height control switch is pressed, a signal is sent from terminal RC of the suspension control 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 suspension control ECU monitors the compressor circuit for abnormalities.

DTC Code	Detection Condition	Trouble Area
C1752	With the AIR SUS relay activated, a lock signal of the height control compressor motor is detected for 4 seconds or more.	Wire harness or connector Height control compressor Suspension control ECU

HINT:

Once the ECU stores DTC C1752 in the memory, the vehicle height control is suspended until a normal signal is input to the ECU from the height control solenoid valves. However, control is resumed if the ignition switch is turned off, then ON again.

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

If DTC C1781 (ECU malfunction) and/or C1782 (power source circuit) is displayed, perform the inspection necessary for DTC C1781 and/or C1782 first.
If DTC C1781 and the C1782 are output at the same time, perform the inspection necessary for DTC C1782 first.

PROCEDURE

1.	INSPECT SUSPENSION CONTROL RELAY (AIR SUS)

(a) Turn the ignition switch off.

(b) Remove the AIR SUS relay from the engine room relay block.

Standard Resistance:

Tester Connection	Condition	Specified Condition
3 - 5	When 12 V battery voltage is not applied to terminal 1 and 2	10 kΩ or higher
3 - 5	When 12 V battery voltage is applied to terminal 1 and 2	Below 1 Ω

2.	CHECK HARNESS AND CONNECTOR (COMPRESSOR - ECU, BATTERY AND BODY GROUND)

(a) Remove the AIR SUS relay from the engine room relay block.

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Condition	Specified Condition
Relay block AIR SUS relay terminal 5 - Body ground	Always	11 to 14 V

(d) Disconnect the O19 ECU connector.

(e) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
Relay block AIR SUS relay terminal 3 - Q7-1 (B)	Always	Below 1 Ω
Relay block AIR SUS relay terminal 3 or Q7-1 (B) - Body ground	Always	10 kΩ or higher
Q7-2 (E) - Body ground	Always	Below 1 Ω
Q7-3 (RM+) - O19-20 (RM+)	Always	Below 1 Ω
Q7-3 (RM+) or O19-20 (RM+) - Body ground	Always	10 kΩ or higher
Q7-4 (RM-) - O19-21 (RM-)	Always	Below 1 Ω
Q7-4 (RM-) or O19-21 (RM-) - Body ground	Always	10 kΩ or higher

3.	INSPECT NO. 1 HEIGHT CONTROL COMPRESSOR (COMPRESSOR MOTOR)

(a) Apply 12 V battery voltage to the compressor motor and check the operation of the motor.

OK:

Measurement Condition

Specified Value

12 V battery positive (+) → Terminal 1 (B)

12 V battery negative (-) → Terminal 2 (E)

Motor operates

NOTICE:

Do not allow the motor to operate for approximately 90 seconds or more.

If the compressor is shorted, locked, or has a similar type of malfunction, a large amount of current will be flowing. Therefore, if the motor does not operate, immediately stop this inspection.