GM Service Manual Online
For 1990-2009 cars only

Circuit Description


Object Number: 305452  Size: LF

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.

Conditions for Setting the DTC

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.

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 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.

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.

  1. This step checks for an internal short circuit condition in the exhaust solenoid valve.

  2. 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

Go to Road Sensing Suspension Diagnostic System Check

2

  1. Turn the ignition OFF.
  2. Remove the ELC fuse from the Rear Junction Block.
  3. Disconnect the CVRSS module connector C1.
  4. Turn the ignition ON with the engine off.
  5. Measure the voltage from CVRSS module connector C1, terminal C14, to ground with a J 39200 DMM.

Is the voltage greater than the specified value?

10 V

Go to Step 3

Go to Step 6

3

  1. Disconnect the ALC compressor.
  2. The ignition remains ON.
  3. Measure the voltage from CVRSS module connector C1, terminal C14, to ground with a DMM.

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?

--

Go to Road Sensing Suspension Diagnostic System Check

--

5

Replace the ALC compressor assembly and all associated air lines. Refer to Air Compressor Replacement .

Is the replacement complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

6

  1. Check CVRSS control module connector C1 and the ALC compressor assembly connector for debris and corrosion.
  2. Install all of the connectors and components that were removed.
  3. Clear the CVRSS DTCs. Refer to Clearing DTCs .
  4. Wait 60 seconds.
  5. Check the CVRSS DTCs. Refer to Displaying Diagnostic Trouble Codes (DTC) .

Is DTC C1737 CURRENT?

--

Go to Step 7

Go to Road Sensing Suspension Diagnostic System Check

7

  1. Turn the ignition OFF.
  2. Replace the CVRSS control module. Refer to Electronic Suspension Control Module Replacement .
  3. Install all of the connectors and components that were removed.
  4. Install the scan tool.
  5. Turn the ignition ON with the engine off.
  6. Important: The controller must be calibrated.

  7. Calibrate the CVRSS service controller using the scan tool. Refer to Electronic Suspension Control Module Calibration .

Is the CVRSS control module calibrated?

--

Go to Road Sensing Suspension Diagnostic System Check

--