Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC C0712 00: Level Control Compressor Relay CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Leveling Compressor Relay Coil B+ | C0712 00 | C0712 00 | -- | -- |
Leveling Compressor Relay Coil Control | C0712 00 | C0712 00 | C0712 00 | -- |
Circuit/System Description
The air suspension control module (ASCM) adjusts the vehicle suspension ride height. The ASCM determines the height of the vehicle based on the voltage from the suspension position sensors. The module grounds the ELC COMP relay and the exhaust control solenoid to raise and lower the vehicle in order to keep the vehicle level.
Conditions for Running the DTC
| • | The ASCM is powered up. |
| • | The ASCM is commanding the compressor ON. |
Conditions for Setting the DTC
| • | The leveling compressor relay coil control circuit is shorted to voltage, ground, or open for 5 seconds. |
| • | The leveling compressor relay coil B+ circuit is shorted to ground or open for 5 seconds. |
Action Taken When the DTC Sets
The air suspension will be inoperative.
Conditions for Clearing the DTC
The ASCM does not detect a failure during the self test.
Diagnostic Aids
This circuit is monitored during every functional operation of the compressor relay output and every 3.3 milliseconds when output is active. If a compressor relay fault is detected, the ASCM retries the output every 15 seconds to try to recover from the fault.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Air Suspension Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, command the compressor relay ON with a scan tool. Listen for the operation of the ELC CMPRSR relay and the air suspension compressor.
Circuit/System Testing
- Ignition OFF, remove the ELC CMPRSR relay.
- Ignition ON, verify that a test lamp does not illuminate between the rear fuse block relay control circuit terminal 11 and ground.
- Verify that a test lamp illuminates between the rear fuse block B+ circuit terminal 15 and ground.
- Connect a test lamp between the B+ circuit terminal 15 and the control circuit terminal 11.
- Command the compressor relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If all circuits test normal, test or replace the ELC CMPRSR relay.
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
| ⇒ | If the test lamp does not illuminate, test the relay B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the air suspension control module. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the air suspension control module. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the air suspension control module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for air suspension control module replacement, setup, and programming |
