GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The Continuously Variable Road Sensing Suspension (CVRSS) module performs checks of internal calibration data. If a fault condition is detected, the CVRSS module will set the fault DTC, and may, depending upon the fault type, turn on the SERVICE SUSPENSION SYS message. Additionally, depending upon the type of the internal fault, the system will either enter a Speed Dependent Damping mode or disable all dampers. In the latter case, a message will be sent to the Powertrain Control Module (PCM) to cause the vehicle speed to be limited. Recovery from any controller fault condition is attempted only after the ignition is cycled ON and OFF.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

    • The DTC is set when any calibration faults internal to the CVRSS module are detected.
    • The fault is detected during three consecutive ignition cycles, or during the same ignition cycle after clearing the DTC with the scan tool.

Action Taken When the DTC Sets

Depending upon which of the internal functions are affected by the fault condition, the CVRSS module will take one of two sets of actions:

    • If the fault condition allows continued output operation, the system will enter a Speed Dependent Damping mode, in which all four corners of the vehicle are concurrently driven by a fixed PWM duty cycle, which increases as a function of the vehicle speed. The SERVICE SUSPENSION SYS will be displayed.
    • If the fault is more severe, the control module will disable ALL dampers by commanding 0 % PWM duty cycle, disabling the damper switched battery circuit, and sending a message to the PCM to limit vehicle speed. The SPEED LIMITED TO XXX and SERVICE SUSPENSION SYS messages 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 senses the hardware fault and the ignition is cycled OFF and ON.

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step checks to see if the problem has cleared after the CVRSS module has been calibrated.

Step

Action

Yes

No

1

Did you perform the Road Sensing Suspension Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Road Sensing Suspension

2

  1. Install the scan tool.
  2. Turn the ignition ON with the engine off.
  3. Calibrate the CVRSS module using the scan tool. Refer to Electronic Suspension Control Module Calibration .
  4. Use the scan tool to clear the DTCs.
  5. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 3

System OK

3

Important: Perform the set up and calibration procedure for the CVRSS module.

Replace the CVRSS module. Refer to Electronic Suspension Control Module Replacement .

Did you complete the replacement?

Go to Step 4

--

4

  1. Use the scan tool in order to clear the DTCs .
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK