Circuit Description
The electronic brake control module (EBCM) monitors vehicle speed deceleration, system activation, and brake pedal position sensor active times in order to calculate an estimate of the brake rotor temperatures. If the EBCM calculates that the brake rotor temperatures have exceeded the thermal cutoff point, the EBCM will temporarily suspend the traction control system (TCS) function until the brake rotors cool. This feature is used to maintain braking effectiveness if normal base braking is required. An overly heated brake system could result in brake fade.
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 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. |
| • | The ignition voltage is greater than 8 volts. |
Conditions for Setting the DTC
When the estimated brake rotor temperature exceeds 375°C (700°F), this DTC sets. 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 antilock brake system (ABS) remains functional. |
| • | The Traction Control indicator turns ON. |
Conditions for Clearing the DTC
| • | The current DTC becomes history when the estimated brake rotor temperatures of both drive wheels is below 275°C (530°F). The following actions also occur: |
| - | The EBCM enables the TCS. |
| - | The driver information center (DIC) displays the Traction Ready message. |
| • | The condition for the DTC is no longer present, the DTC is not current, and you used the scan tool Clear DTC function. |
| • | The condition for the DTC is no longer present, the DTC is not current, and you used the On-Board Diagnostics Clear DTC function. |
| • | 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 fault is present. This DTC indicates that the EBCM has reacted to the brake rotor over temperature and the TCS is temporarily disabled.
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 | |
Since most occurrences of this DTC are caused by excessive 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 |
