Pinpoint Test J: The Air Compressor Continuously Cycles With The Ignition Switch In The Off Position And No DTCs Are Set

Vehicle Dynamic Suspension

Pinpoint Tests


Pinpoint Test J: The Air Compressor Continuously Cycles with the Ignition Switch in the OFF Position and No DTCs Are Set

Refer to Wiring Diagram Set 41, Vehicle Dynamic Suspension for schematic and connector information. Diagrams By Number

Normal Operation

When the Vehicle Dynamics Module (VDM) engages the air suspension relay, fused battery voltage is supplied to the air suspension compressor along circuit 538 (GY/RD). The compressor is provided a ground path along circuit 57 (BK).

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Air compressor relay
- Air compressor assembly
- VDM



PINPOINT TEST J: THE AIR COMPRESSOR CONTINUOUSLY CYCLES WITH THE IGNITION SWITCH IN THE OFF POSITION AND NO DTCS ARE SET

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J1 CHECK FOR MODULE ACTIVITY


NOTE: The VDM is powered for approximately 60 minutes after the ignition switch is placed in the OFF position. During this time, the air suspension will correct for vehicle weight by raising the vehicle.

- Ignition OFF.
- Turn the air suspension switch to the OFF position.
- Verify the air compressor still cycles 60 minutes after the ignition switch is placed in the OFF position.
- Does the air compressor still cycle continuously after the VDM is disabled?

Yes
GO to J2.

No
The system is OK.

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J2 CHECK THE VDM


- Disconnect: VDM C2131a.
- Does the air compressor still cycle?

Yes
GO to J3.

No
INSTALL a new VDM. REFER to Vehicle Dynamics Module (VDM) Service and Repair. TEST the system for normal operation.

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J3 CHECK THE AIR SUSPENSION RELAY FOR A SHORT TO VOLTAGE


- Disconnect: Air Suspension Relay.
- Does the air compressor still cycle?

Yes
GO to J4.

No
INSTALL a new air suspension relay. TEST the system for normal operation.

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J4 CHECK CIRCUIT 538 (GY/RD) FOR A SHORT TO VOLTAGE


- Disconnect: Air Compressor C1179.
- Measure the voltage between air compressor C1179-2, circuit 538 (GY/RD), harness side and ground.




- Is any voltage present?

Yes
REPAIR circuit 538 (GY/RD). REPEAT the self-test.

No
INSTALL a new air suspension compressor. REFER to Air Suspension Compressor Service and Repair. TEST the system for normal operation.

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