ABS - Integrated Chassis Control

DTC C1238: Brake Thermal Model Limit Exceeded:

DTC C1238:

CIRCUIT DESCRIPTION
The EBTCM monitors vehicle speed deceleration, ABS/TCS/ICCS activation, and brake lamp ON times to calculate brake rotor temperatures. When brake rotor temperatures are exceeded, TCS is disabled, DTC C1238 is set, and the TRACTION SUSPENDED message is displayed. If brake usage is reduced during driving, brake rotor cooling is calculated and TCS is reenabled.

CONDITION FOR SETTING THE DTC
DTC C1238 could be set when either driven wheel estimated brake rotor temperature exceeds 375° C (700° F). If either driven wheel estimated brake rotor temperature has exceeded 375° C (700° F) during ABS or normal braking conditions, the code will not be set until the next TCS activation occurs. The code will not be set and TCS will not be disabled if both rotor estimated temperatures have cooled below 275° C (530° F) before the next TCS activation. If either driven wheel brake rotor temperatures has exceeded 375° C (700° F) during TCS then the code will be set immediately, but TCS will not be disabled until the end of the TCS event.

ACTION TAKEN WHEN THE DTC SETS
A malfunction DTC is stored, TCS is disabled and the TRACTION SUSPENDED message is displayed.

CONDITIONS FOR CLEARING THE DTC
Condition for DTC is no longer present and scan tool clear DTC function is used. Fifty start cycles have passed with no DTCs detected.

DIAGNOSTIC AIDS
- Excessive brake usage
- Excessive TCS usage
- The temperature values are an estimated figure calculated by the EBTCM. If the driven wheel brake rotors are known to be below 275° C (530° F), and the Brake Lamp Switch is properly adjusted and the Brake Lamp Switch CKT is OK, the likely cause of the malfunction is a defective EBTCM.

TEST DESCRIPTION
The numbers below refer to step numbers on the diagnostic table.
3. Reads TCS status, disabled implies that the Brake Thermal Model has been exceeded.