GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC C0242: PCM Indicated TCS Malfunction

Circuit/System Description

The electronic brake control module (EBCM) and the powertrain control module (PCM) simultaneously control the traction control. The EBCM sends a serial data message to the PCM requesting torque reduction. When certain PCM DTCs are set, the PCM will not be able to perform the torque reduction for traction control. A serial data message is sent to the EBCM indicating that traction control is not allowed.

Conditions for Running the DTC

    • The ignition is ON.
    • Ignition voltage is greater than 8 volts.

Conditions for Setting the DTC

The PCM diagnoses a condition preventing the engine control portion of the traction control function and sends a serial data message to the EBCM indicating that torque reduction is not allowed. The PCM will typically set a DTC and the EBCM will set this DTC.

Action Taken When the DTC Sets

    • The EBCM disables the TCS for the duration of the ignition cycle.
    • The Traction Off indicator turns ON.
    • The message center displays the Service Traction System message.
    • The ABS 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 electronic brake control module (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.

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

ABS Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for Scan Tool Information

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.