C1751

SUSPENSION CONTROL: AIR SUSPENSION SYSTEM: C1751: Compressor Relay Coil Malfunction
C1751 - Compressor Relay Coil Malfunction

DESCRIPTION

The signal from suspension control ECU switches the suspension control relay on, and then the height control compressor motor starts.





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
- Before performing troubleshooting, inspect the connectors of related circuits.
- Before replacing the suspension control ECU, perform all of the following again: 1) symptom simulation Electronic Circuit Inspection Procedure; 2) DTC inspection; and 3) Techstream inspection (Data List or Active Test). If no malfunctions are found in other areas, replace the suspension control ECU.
- If the suspension control ECU or height control sensor is replaced, the vehicle height offset calibration must be performed Programming and Relearning.

PROCEDURE

1. CLEAR DTC

(a) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.

NEXT -- Continue to next step.

2. CHECK MOTOR RELAY OPERATION (ACTIVE TEST)

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG) and the Techstream on.

(d) Enter the following menus: Chassis / Air suspension / Active Test.

(e) Check the operation sound of the height control solenoid valve when the solenoid is turned on through the Active Test.

Air suspension





OK:

Operation of solenoid (clicking sound) can be heard

NG -- INSPECT SUSPENSION CONTROL RELAY (AIR SUS)
OK -- Continue to next step.

3. RECONFIRM DTC

(a) Perform a road test.

(b) Check for DTC Reading and Clearing Diagnostic Trouble Codes.

Result





B -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting
A -- Continue to next step.

4. INSPECT SUSPENSION CONTROL RELAY (AIR SUS)

(a) Turn the engine switch off.

(b) Remove the suspension control relay from the engine room No. 1 relay block.





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

Standard Resistance:





NG -- REPLACE SUSPENSION CONTROL RELAY
OK -- Continue to next step.

5. CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL RELAY - ECU AND BODY GROUND)

(a) Disconnect the L88 ECU connector.

(b) Remove the suspension control relay from the engine room No. 1 relay block.





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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE SUSPENSION CONTROL ECU Removal