C0658

Circuit Description
The Automatic Level Control compressor is switched ON and OFF using an Electronic Level Control (ELC) compressor relay which is controlled by the Continuously Variable Road Sensing Suspension (CVRSS) module. The CVRSS module circuitry provides a switched path to ground (low-side drive) whenever compressor activity is required. This drive circuit is also continually monitored to determine if the voltage level agrees with the commanded state.

Conditions for Running the DTC
The ignition is ON.

Conditions for Setting the DTC
DTC C0657
The following conditions must be present to set the DTC:
^ The CVRSS module detects voltage less than a preset value in the compressor motor control circuit during a compressor OFF state test.
^ The fault is detected during three consecutive ignition cycle or during the same ignition cycle after clearing the DTC with a scan tool.

DTC C0658
The following conditions must be present to set the DTC:
^ The CVRSS module detects voltage greater than a preset value in the compressor motor control circuit during a compressor ON state test.
^ The fault is detected during three consecutive ignition cycles, or during the same ignition cycle after clearing the DTC with a scan tool.

Action Taken When the DTC Sets
The ELC compressor relay output drive is disabled for the remainder of the ignition cycle.

Conditions for Clearing the MIL/DTC
^ The scan tool can be used to clear the DTC.
^ The DTCs saved as history when the CVRSS module no longer sees an out of range voltage condition in the compressor motor control circuit.
The DTC will clear if the fault does not return after 50 consecutive ignition cycles.

Diagnostic Aids
These DTCs are set only by electrical problems with the ELC compressor relay coil circuit. Compressor motor problems and pneumatic leakage problems do not set these DTCs.

Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
2. Listen for an audible click when the ELC Relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
3. Tests for voltage at the coil side of the ELC Relay. The ELC Fuse supplies power to the coil side of the ELC Relay.
4. Verifies that the CVRSS module is providing ground to the ELC Relay.
5. Tests if ground is constantly being applied to the ELC Relay.