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C1751








SUSPENSION CONTROL: AIR SUSPENSION SYSTEM: C1751/51: Continuous Electric Current to Height Control Compressor

DTC C1751/51 - Continuous Electric Current to Height Control Compressor

DESCRIPTION

The signal from the suspension control ECU operates the air suspension relay, and the height control compressor motor starts.
The height control compressor assembly operates until the targeted vehicle height is reached. Then the height control sensor sub-assembly sends the signal to the suspension control ECU, and stops the height control compressor.






INSPECTION PROCEDURE

PROCEDURE

1. CHECK VEHICLE HEIGHT
HINT: Make the vehicle vacant and unloaded.

NEXT -- Continue to next step.
2. CHECK HEIGHT CONTROL COMPRESSOR CIRCUIT
NEXT -- Continue to next step.
3. CHECK AIR LEAKAGE
OK:
No leaks
Result:






C -- REPAIR OR REPLACE AIR TUBE
B -- INSPECT HEIGHT CONTROL SOLENOID VALVE
A -- Continue to next step.
4. INSPECT HEIGHT CONTROL SOLENOID VALVE
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position, and push the intelligent tester main switch on.
(c) Select the item below in the ACTIVE TEST, and operate it with the intelligent tester.
AIRSUS:





(d) Check whether the height control solenoid valve has a continuity (will vibrate).
OK:
The solenoid makes sound, and the height control solenoid valve has continuity (will vibrate).
OK -- INSPECT EXHAUST SOLENOID VALVE
NG -- Continue to next step.
5. INSPECT HEIGHT CONTROL SOLENOID VALVE





(a) HEIGHT CONTROL SOLENOID VALVE FRONT RH:
(1) Disconnect the height control solenoid valve connector.
(2) Check the operating sound of the height control solenoid valve when positive battery voltage is applied to the terminals.






OK:
It should make an operating sound (click).
Result:





HINT: When a malfunction is found in the front solenoid valve, replace the height control valve sub-assembly No. 1.





(b) HEIGHT CONTROL SOLENOID VALVE FRONT LH:
(1) Disconnect the height control solenoid valve connector.
(2) Check the operating sound of the height control solenoid valve when positive battery voltage is applied to the terminals.






OK:
It should make an operating sound (click).
Result:





HINT: When a malfunction is found in the front solenoid valve, replace the height control valve sub-assembly No. 1.





(c) HEIGHT CONTROL SOLENOID VALVE REAR RH:
(1) Disconnect the height control solenoid valve connector.
(2) Check the operating sound of the height control solenoid valve when positive battery voltage is applied to the terminals.






OK:
It should make an operating sound (click).
Result:





HINT: When a malfunction is found in the front solenoid valve, replace the height control valve sub-assembly No. 2.





(d) HEIGHT CONTROL SOLENOID VALVE REAR LH:
(1) Disconnect the height control solenoid valve connector.
(2) Check the operating sound of the height control solenoid valve when positive battery voltage is applied to the terminals.






OK:
It should make an operating sound (click).
Result:





HINT: When a malfunction is found in the front solenoid valve, replace the height control valve sub-assembly No. 2.

C -- REPLACE HEIGHT CONTROL VALVE SUB-ASSEMBLY NO.2
B -- REPLACE HEIGHT CONTROL VALVE SUB-ASSEMBLY NO.1
A -- Continue to next step.
6. INSPECT EXHAUST SOLENOID VALVE





(a) Disconnect the exhaust solenoid valve connector.
(b) Check the operating sound of the exhaust solenoid valve when positive battery voltage is applied to the terminals.






OK:
It should make an operating sound (click).
Result:






C -- REPLACE EIGHT CONTROL COMPRESSOR ASSEMBLY
B -- INSPECT TANK SOLENOID VALVE
A -- Continue to next step.
7. INSPECT TANK SOLENOID VALVE
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position, and push the intelligent tester main switch on.
(c) Select the item below in the ACTIVE TEST, and operate it with the intelligent tester.
AIRSUS:





(d) Check whether the tank solenoid valve has a continuity (will vibrate).
OK:
The solenoid makes sound, and the tank solenoid valve has a continuity (will vibrate).
OK -- INSPECT HEIGHT CONTROL SENSOR LINK SUB-ASSEMBLY
NG -- REPLACE PNEUMATIC W/TUBE TANK ASSEMBLY
8. INSPECT TANK SOLENOID VALVE





(a) Disconnect the tank solenoid valve connector.
(b) Check the operating sound of the tank solenoid valve when positive battery voltage is applied to the terminals.






OK:
It should make an operating sound (click).
HINT: When a malfunction is found in the tank solenoid valve, replace the pneumatic tank assembly.

NG -- REPLACE PNEUMATIC W/TUBE TANK ASSEMBLY
OK -- Continue to next step.
9. INSPECT HEIGHT CONTROL SENSOR LINK SUB-ASSEMBLY
(a) Inspect and adjust the height control sensor link sub-assembly .
NEXT -- Continue to next step.
10. SYSTEM CHECK
(a) Change the height control switch to the "N" position.
(b) Change the height control switch to the "H" position.
(c) Check that the vehicle height changes from the "N" to the "H" position.
HINT: When the vehicle height does not change, proceed to the next step.

NEXT -- CHECK AIR SUSPENSION SYSTEM
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