GM Service Manual Online
For 1990-2009 cars only

DTC C1251 w/F45

Circuit Description

The CVRSS calculates normal force and transmits a PWM signal to the EBCM via two dedicated data lines, one right, and one left. The EBCM supplies the pull up voltage. The EBCM uses this information to detect rough road conditions and allows for more aggressive braking on rough surfaces.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The CVRSS diagnoses a condition in the road sensing suspension system and sends a serial data message to the EBCM. The CVRSS will typically set a DTC and the EBCM will set this DTC.

Action Taken When the DTC Sets

    • The EBCM disables the rough road detection function of the VSES for the duration of the ignition cycle.
    • The ABS/TCS/VSES remains functional.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

This DTC is for information only. As an aid to the technician, this DTC indicates that there are no problems in the ABS/TCS system.

Step

Action

Yes

No

Schematic Reference: Antilock Brake System Schematics

1

Did you perform the ABS Diagnostic System Check?

Go to Diagnostic System Check - Road Sensing Suspension in Road Sensing Suspension (RSS)

Go to Diagnostic System Check - ABS