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 C0179: System Thermal High

Circuit Description

The electronic brake control module (EBCM) monitors vehicle speed deceleration, antilock brake system (ABS) activation, traction control system (TCS) activation and brake pedal position in order to calculate an estimate of the brake rotor temperatures. In most cases high brake rotor temperature is caused by extended TCS activation. If the EBCM calculates that the brake rotor temperatures are too high, the EBCM will temporarily suspend the TCS function until the brake rotors cool. The EBCM continues calculating the brake rotor temperatures after the ignition is turned OFF. The EBCM remains awake until the EBCM calculates that the brake rotors have cooled sufficiently. The cooling period may take up to 30 minutes.

Conditions for Running the DTC

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

Conditions for Setting the DTC

This DTC sets when the estimated brake rotor temperature exceeds 375°C (700°F). When the estimated brake rotor temperature exceeds 375°C (700°F) during normal braking or ABS operations, the DTC does not set until the next TCS activation. The EBCM does not disable TCS until the end of the TCS event.

Action Taken When the DTC Sets

    • The EBCM disables the TCS until the DTC becomes a history DTC.
    • The ABS remains functional.
    • The Traction Control Off Indicator turns ON.

Conditions for Clearing the DTC

The current DTC becomes history when the estimated brake rotor temperatures of both drive wheels decreases below 275°C (530°F). The following actions also occur:

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

Diagnostic Aids

DTC C0179 does not indicate a malfunction has occurred. This DTC indicates that the EBCM has reacted to high brake rotor temperatures by temporarily suspending TCS.

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

Circuit/System Testing

    Important: Allow brakes to cool down before performing test.

  1. With scan tool clear the DTC.
  2. With scan tool connected test drive the vehicle under normal braking conditions and without causing TCS or ABS activation. Verify DTC C0179 does not reset.
  3. If the DTC resets, replace the EBCM.
  4. Refer to Diagnostic Aids.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for EBCM replacement, setup, and programming