The ALC exhaust solenoid valve is controlled (switched ON or OFF) by the CVRSS 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 module is also continually monitored to determine if the voltage level agrees with the commanded state.
The DTC is set when the CVRSS 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 module no longer senses a high voltage condition at pin C14, when the exhaust solenoid valve is in an ON-state.
• | All rear leveling activity for the remainder of the ignition cycle will be disabled. |
• | The SERVICE RIDE CONTROL message will be displayed. |
• | Use the scan tool. |
• | Use the On-Board diagnostic CLEAR RSS CODES feature. |
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 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 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.
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.
This step checks for an internal short circuit condition in the exhaust solenoid valve.
This step checks for a short to battery condition in circuit 320.
Step | Action | Value(s) | Yes | No |
---|---|---|---|---|
1 | Was the Road Sensing Suspension Diagnostic System Check performed? | -- | Go to Step 2 | |
2 |
Is the voltage greater than the specified value? | 10 V | Go to Step 3 | Go to Step 6 |
3 |
Is the voltage greater than the specified value? | 10 V | Go to Step 4 | Go to Step 5 |
4 | Repair the short circuit to voltage condition in circuit 320. Is the repair complete? | -- | -- | |
5 | Replace the ALC compressor assembly and all associated air lines. Refer to Air Compressor Replacement . Is the replacement complete? | -- | -- | |
6 |
Is DTC C1737 CURRENT? | -- | Go to Step 7 | |
7 |
Important: The controller must be calibrated. Is the CVRSS control module calibrated? | -- | -- |