C0663

Circuit Description
The Electronic Level Control exhaust solenoid valve is switched ON or OFF by the Continuously Variable Road Sensing Suspension (CVRSS) module. The control module provides a low-side drive (switched to ground) whenever exhaust activity is required and during a head-relief sequence which occurs before each compressor start-up. This drive output from the CVRSS module is 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 C0662
The following conditions must be present to set the DTC:
^ The CVRSS module detects voltage less than a preset value in the exhaust solenoid control circuit during an exhaust solenoid valve OFF 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.

DTC C0663
The following conditions must be present to set the DTC:
^ The CVRSS module detects voltage greater than a preset value in the exhaust solenoid control circuit during an exhaust solenoid valve 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
^ ALL rear leveling activity for the remainder of the ignition cycle will be disabled.
^ The SERVICE RIDE CONTROL 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 CVRSS module no longer sees an out of range voltage condition in the exhaust solenoid 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 exhaust solenoid control circuit. Pneumatic blockage problems do not set these DTCs.
A temporary compressor overload, such as high head pressure during a cold start, may cause the ELC fuse to open. This is one possible cause of DTC C0662.

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