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 tempreture 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.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0179 System Thermal High
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.
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
Most occurrences of this DTC are caused by excessive TCS activation or braking. Review with the customer to verify the conditions under which the DTC set. Did vehicle operation cause this DTC to set? | Go to Step 3 | Go to Diagnostic Aids | |
3 |
Does the DTC reset? | Go to Step 1 | System OK |
