C0712
DTC C0712
Circuit Description
The Automatic Level Control (ALC) System uses a relay to control compressor activity. The ignition 3 circuit provides battery voltage to the coil side of the ALC compressor relay. The electronic suspension control (ESC) module circuitry provides a switched path to ground controlling the compressor relay. This circuit is also monitored to determine if the voltage level agrees with the commanded state.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0712 Level Control Compressor Relay Circuit
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The following conditions must be present to set the DTC:
* The ESC module detects voltage less than a preset value in the compressor motor control circuit during a compressor OFF state test.
* The ESC 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 ESC disables the ALC relay for the remainder of the ignition cycle.
* The SERVICE SUSPENSION SYSTEM message will be displayed.
Conditions for Clearing the MIL/DTC
* The scan tool can be used to clear the DTC.
* The DTC is saved as history when the ESC 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 ALC compressor relay coil circuit. Compressor motor problems and pneumatic leakage problems do not set these DTCs.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. Tests for voltage in the Automatic Level Control relay coil supply voltage circuit.
3. Tests for a short to voltage in the Automatic Level Control relay coil supply voltage circuit.
