Antilock Braking System (ABS)

DTC 38 Brake Thermal Model Limit Exceeded:

CIRCUIT DESCRIPTION
The EBTCM monitors vehicle speed, deceleration, ABS/TCS activation, and brake lamp "ON" times to calculate brake rotor temperatures. When brake rotor temperatures are exceeded, TCS is disabled, DTC 38 is set, and the "TCS OFF" indicator is turned "ON" after the next TCS event. If brake usage is reduced during driving, brake rotor cooling is calculated and TCS is reenabled. Excessive braking and/or TCS could result in degraded braking performance or possible damage to the rotors and/or brake pads.

DTC WILL SET WHEN
DTC 38 could be set when either driven wheel estimated brake rotor temperature exceeds (375°C).

If either driven wheel estimated brake rotor temperature has exceeded (375°C) 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) during TCS then the code will be set immediately, but TCS will not be disabled until the end of the TCS event.

ACTION TAKEN
A malfunction code is stored. The "TRACTION OFF" indicator is turned "ON" and TCS is disabled as long as both driven wheel brake rotor temperatures are above 275° C (530° F). If the rotor temperatures cool below 275° C (530° F), then the "TRACTION OFF" indicator will be turned off. The DTC stays stored even if TCS has been enabled again.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Checks to see if any other DTCs are set.
2. Checks to see if DTC 38 is set as a current code.
3. Lets brakes cool for 20 minutes and then rechecks to see if the Brake Thermal Model (BTM) limit remains exceeded.

DIAGNOSTIC AIDS
Possible causes:
^ 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 probably a defective EBTCM.