C1737

CIRCUIT DESCRIPTION
The ALC exhaust solenoid valve is controlled (switched ON or OFF) by the CVRSS control module. The control module provides a low-side drive (switched to ground) whenever exhaust activity is required and during a head-relief sequence. The head-relief sequence occurs at compressor start-up. This drive output from the CVRSS control module is also continually monitored to determine if the voltage level agrees with the commanded state.

CONDITIONS FOR SETTING THE DTC
The DTC is set when the CVRSS control module measures a feedback voltage condition at pin C14 greater than a preset threshold during an exhaust solenoid valve ON-state. The DTC will turn HISTORY when the CVRSS control module no longer senses a high voltage condition at pin C 14, when the exhaust solenoid valve is in an ON-state.

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
^ Use the scan tool.
^ Use the On-Board diagnostic CLEAR RSS CODES feature.

DIAGNOSTIC AIDS
This fault condition is detectable only when the exhaust solenoid valve output is commanded to the ON-state, which occurs before each compressor start-up and whenever a downward correction is necessary. The CVRSS control module expects to see a low voltage condition during the ON-state.

Only electrical problems with the exhaust solenoid valve are flagged. Pneumatic blockage problems do not set a DTC, but the CVRSS control module shuts off the exhaust function if no progress is made or if excessive run time occurs. Recovery is not attempted until the ignition is cycled OFF and ON.

TEST DESCRIPTION

IMPORTANT:
^ Do not backprobe the sensors, actuators, or any sealed connectors.
^ When all the diagnostics and repairs are complete, clear the DTCs, and verify the operation.

The number(s) below refer to the step number(s) on the diagnostic table.
2. This step checks for an internal short circuit condition in the exhaust solenoid valve.
3. This step checks for a short to battery condition in CKT 320.