C1242

DTC C1242: Rear ESB Will Not Hold Motor:

DTC C1242 Schematic:

Circuit Description
This DTC is designed to detect a slipping rear ESB. During initialization, the rear motor is rehomed. If the ESB slips, the motor will move. During the next initialization, a rehome of the motor verifies the motor remained at the home position. If motor movement is detected, the ESB must be slipping.

Conditions for Setting the DTC
This DTC will set when the following conditions are met:
^ Forward movement of the rear motor is detected (motor feedback current is less than the motor stall current [12A]).
^ This test checks if rear hydraulic modulator pistons are in the home position during initialization.
^ This DTC can be set during initialization.
^ DTC C1286 is always set with this DTC.

Action Taken When the DTC Sets
If the ESB cannot hold the motor, the motor may be back driven when the brake pedal is applied causing the rear hydraulic modulator pistons to be away from home position. A malfunction DTC is stored, ABS is disabled and both the amber ABS indicator lamp and the red BRAKE warning lamp are turned ON.

Conditions for Clearing the DTC
^ Conditions for the malfunction are no longer present and the Tech 2 scan tool Clear DTC Information function is used.
^ One hundred drive cycles have passed with no malfunctions detected.

Diagnostic Aids
The following list contains items that need to be inspected when diagnosing this system:
^ Faulty motor pack.
^ Faulty hydraulic modulator (rear pistons sticking and not returning to home position).
An intermittent malfunction in this DTC may result from a mechanical part of the system that sticks, binds, or slips.

The frequency of the malfunction can be checked by using the Enhanced Diagnostic function of the Tech 2 scan tool as described in Diagnosis found in this section.



Test Description
The numbers below refer to step numbers on the diagnostic table.
2. Checks the ability of the ESB to hold the motor. A broken or faulty ESB would result in the rear piston being back driven by hydraulic pressure therefore the rear wheels would move.
3. Releases the tension of the motor pack prior to its removal from the hydraulic modulator.