Pinpoint Test J: The Air Compressor is Inoperative

Vehicle Dynamic Suspension

Pinpoint Test J: The Air Compressor is Inoperative

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

Normal Operation

The Vehicle Dynamics Module (VDM) will activate the air compressor once certain conditions are met. To activate the air compressor, the VDM (Vehicle Dynamics Module) supplies voltage to the air compressor relay along circuit CCL01 (WH/VT). This voltage passes through the coil side of the relay and to ground along GD123 (BK/GY), which energizes the relay. The switch side of the relay receives fused battery voltage from Battery Junction Box (BJB) fuse 19 (60A) along circuit SBB19 (BU/RD). When the relay is energized, the switch side closes and this fused battery voltage is sent to the air compressor along circuit CCL08 (BU/BN). The voltage passes through the air compressor and to ground along circuit GD123 (BK/GY), which activates the air compressor.

To protect the air compressor from damage due to excessive run time and heat build up, the air compressor assembly contains a temperature sensitive, thermal circuit breaker and the VDM (Vehicle Dynamics Module) contains software to monitor how long the compressor has been running. The circuit breaker will protect the compressor from damage due to overheating by disabling the compressor when the compressor reaches a pre-determined temperature threshold. Once the compressor has been disabled and has had sufficient time to cool (approximately 15 minutes), the circuit breaker will reset and allow the compressor to function. The VDM (Vehicle Dynamics Module) will also monitor the amount of time the air compressor runs. Once the run time has reached a pre-determined limit, the VDM (Vehicle Dynamics Module) will set DTC C1964 and disable the air compressor until it has had sufficient time to cool down.

- DTC C1830 (Air Compressor Relay Circuit Failure)- With the ignition in the RUN position and during a deflate (vent) or inflate (pump) event, if the VDM (Vehicle Dynamics Module) detects an open, a short to voltage or a short to ground on circuit CCL01 (WH/VT), DTC C1830 will be set.

- DTC C1964 (Compressor Run Time Exceeded)- With the ignition in the RUN position and during an inflate (pump) event, if the air compressor exceeds a pre-determined run time limit, DTC C1964 will be set.

This pinpoint test is intended to diagnose the following:

- Fuse(s)

- Wiring, terminals or connectors

- Air compressor relay

- Air compressor

- VDM (Vehicle Dynamics Module)

PINPOINT TEST J : THE AIR COMPRESSOR IS INOPERATIVE

NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.

J1 ISOLATE THE AIR COMPRESSOR RELAY

- Carry out the mini-ISO relay component test.

- Inspect the relay and socket for corrosion, pushed-out pins and spread terminals.

Does the air compressor relay pass the test and are the relay and socket OK?

Yes
GO to J2.

No
REPAIR or INSTALL a new air compressor relay as necessary. CLEAR the DTC. REPEAT the self-test.

J2 CHECK VDM (Vehicle Dynamics Module) DTCs

- Review the VDM (Vehicle Dynamics Module) DTCs retrieved during Inspection and Verification.

Are any VDM (Vehicle Dynamics Module) DTCs present?

Yes
If only DTC C1964 is present, ALLOW the air compressor a minimum of 10 minutes to cool. CLEAR the DTCs. REPEAT the self-test.

If DTC C1830 is present, GO to J7.

If DTC C1726 is present, GO to J3.

For all other DTCs, GO to the Vehicle Dynamics Module (VDM) DTC Chart. Suspension Control ( Automatic - Electronic )

No
GO to J3.

J3 CHECK THE VOLTAGE TO THE AIR COMPRESSOR RELAY

NOTE: Make sure the battery voltage is greater than 10 volts before testing the compressor relay voltage.

- Ignition OFF.

- Disconnect: Air Compressor Relay.

- Measure the voltage between air compressor relay, circuit SBB19 (BU/RD), harness side and ground.





Is the voltage greater than 10 volts?

Yes
GO to J4.

No
VERIFY BJB (Battery Junction Box) fuse 19 (60A) is OK. If OK, REPAIR circuit SBB19 (BU/RD). If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams. CLEAR the DTCs. REPEAT the self-test.

J4 CHECK CIRCUIT CCL08 (BU/BN) FOR AN OPEN

- Disconnect: Air Compressor Assembly C1179.

- Measure the resistance between air compressor relay, circuit CCL08 (BU/BN), harness side and air compressor assembly C1179-2, circuit CCL08 (BU/BN), harness side.





Is the resistance less than 5 ohms?

Yes
GO to J5.

No
REPAIR circuit CCL08 (BU/BN). CLEAR the DTCs. REPEAT the self-test.

J5 CHECK THE COMPRESSOR GROUND CIRCUIT FOR AN OPEN

- Measure the resistance between air compressor assembly C1179-1, circuit GD123 (BK/GY), harness side and ground.





Is the resistance less than 5 ohms?

Yes
GO to J6.

No
REPAIR circuit GD123 (BK/GY). TEST the system for normal operation.

J6 ISOLATE THE AIR COMPRESSOR

NOTICE: Do not run the air compressor for more than 3 minutes. The air compressor can overheat and stop operating due to an internal temperature sensitive thermal breaker.

- Connect: Air Compressor Assembly C1179.

- Install a fused jumper wire between air compressor relay, circuit SBB19 (BU/RD) and circuit CCL08 (BU/BN).

Does the air compressor run?

Yes
REMOVE the jumper wire. GO to J11.

No
REMOVE the jumper wire. INSTALL a new air compressor. REFER to Air Suspension Compressor . CLEAR the DTCs. REPEAT the self-test.

J7 CHECK THE RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE

- Disable the air suspension system. Refer to Air Suspension System Disable/Enable .

- Ignition OFF.

- Disconnect: VDM (Vehicle Dynamics Module) C2131A.

- Disconnect: Air Compressor Relay.

- Ignition ON.

- Measure the voltage between air compressor relay, circuit CCL01 (WH/VT), harness side and ground.





Is any voltage present?

Yes
REPAIR circuit CCL01 (WH/VT). CLEAR the DTCs. REPEAT the self-test.

No
GO to J8.

J8 CHECK THE RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND

- Ignition OFF.

- Measure the resistance between air compressor relay, circuit CCL01 (WH/VT), harness side and ground.





Is the resistance greater than 10,000 ohms?

Yes
GO to J9.

No
REPAIR circuit CCL01 (WH/VT). CLEAR the DTCs. REPEAT the self-test.

J9 CHECK THE RELAY CONTROL CIRCUIT FOR AN OPEN

- Measure the resistance between air compressor relay, circuit CCL01 (WH/VT) and VDM (Vehicle Dynamics Module) C2131A-6, circuit CCL01 (WH/VT), harness side.





Is the resistance less than 5 ohms?

Yes
GO to J10.

No
REPAIR circuit CCL01 (WH/VT). CLEAR the DTCs. REPEAT the self-test.

J10 CHECK THE AIR COMPRESSOR RELAY GROUND FOR AN OPEN

- Disconnect: Air Compressor Relay.

- Measure the resistance between air compressor relay, circuit GD123 (BK/GY), harness side and ground.





Is the resistance less than 5 ohms?

Yes
GO to J11.

No
REPAIR circuit GD123 (BK/GY). CLEAR the DTCs. REPEAT the self-test.

J11 CHECK THE VDM (Vehicle Dynamics Module) OPERATION

- Check the VDM (Vehicle Dynamics Module) connector for:
- corrosion.
- pushed-out pins.
- spread terminals.


- Connect: VDM (Vehicle Dynamics Module) C2131A (if previously disconnected).

- Connect: Air Compressor Relay (if previously disconnected).

- Make sure the connectors are seated correctly then enable the air suspension system. Refer to Air Suspension System Disable/Enable .

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new VDM (Vehicle Dynamics Module). REFER to Vehicle Dynamics Module (VDM) . CLEAR the DTCs. REPEAT the self-test.

No
The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector.