GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The EBTCM monitors vehicle speed deceleration, ABS/TCS/Stabilitrak® activation, and brake switch ON times in order to calculate the brake rotor temperatures. As brake rotor usage reduces during driving, the EBTCM calculates the brake rotor cooling and the TCS re-enables.

The EBTCM may continue the monitoring of the brake rotor temperature after you turn the ignition OFF. The EBTCM remains awake until the EBTCM calculates that the brake rotors cooled sufficiently. The cooling period may take up to 30 minutes.

Conditions for Setting the DTC

This DTC sets when the estimated brake rotor temperature of either of the drive wheels exceeds 375°C (700°F). When the estimated brake rotor temperature of either of the drive wheels exceeds 375°C (700°F) during normal braking or normal ABS operations, the DTC does not set until the next TCS activation. The brake rotor temperature can exceed 375°C (700°F) without setting the DTC if a TCS activation has not occurred. When the estimated brake rotor temperature of either of the drive wheels exceeds 375°C (700°F) during a TCS activation, the DTC sets immediately, but the EBCM does not disable TCS until the end of the TCS event.

Action Taken When the DTC Sets

    • A malfunction DTC is stored.
    • The TCS is disabled.
    • The DIC displays the TRACTION SUSPENDED message.
    • The ABS remains functional.

Conditions for Clearing the DTC

    • The condition for DTC is no longer present and you used scan tool Clear DTCs function.
    • The condition for DTC is no longer present and you used the On-Board Clear DTCs function.
    • The EBTCM does not detect the DTC in 50 drive cycles.

Diagnostic Aids

    • The temperature is an estimate calculated by the EBTCM.
    • Possible causes of this DTC are the following conditions:
       - The brake usage is excessive.
       - The TCS usage is excessive.
       - The stoplamp/BTSI switch is misaligned or damaged.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step reads the TCS status.

DTC C1238 Brake Thermal Model Exceeded

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check

2

  1. Turn the ignition switch to the RUN position with the engine off.
  2. Use a scan tool in order to read the ABS/TCS DTCs.

Are there any other DTCs?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

  1. Allow the vehicle to cool for 30 minutes after driving.
  2. Use a scan tool set to the ABS Data List in order to read the TCS status.

Is the BTM exceeded?

--

Go to Step 4

Go to Step 5

4

Replace the electronic brake traction control module (EBTCM). Refer to Electronic Brake Control Module Replacement .

Did you complete the repair?

--

Go to Diagnostic System Check

--

5

Inspect the stoplamp switch for misadjustment.

Is the switch misadjusted?

--

Go to Stop Lamp Switch Adjustment in Hydraulic Brakes

Go to Diagnostic System Check