C1242

DTC C1242 (1 Of 2):

DTC C1242 (2 Of 2):

CIRCUIT DESCRIPTION
This DTC is designed to detect a slipping rear axle ESB. During initialization and braking, the rear motor is rehomed. If the ESB slips, the motor/piston will move. During the next key to RUN initialization, a rehome of the motor verifies the motor/piston remained at the home position. If motor movement is detected, the ESB must be slipping.

CONDITIONS FOR SETTING THE DTC
DTC C1242 can be set during brake motor initialization at 0 km/h (0 mph) with the brake off. DTC C1242 can also be set during brake motor initialization at 5 km/h (3 mph) with the brake on. If the EBCM detects that the ESB could not hold the piston in the home position, a malfunction exists. DTC C1286 is always set with DTC C1242.

ACTION TAKEN WHEN THE DTC SETS
If an ESB cannot hold a piston in the home position, the piston may be back-driven when the brake pedal is applied, causing the brake pedal to drop. A malfunction DTC is stored, ABS is disabled, the amber ABS warning indicator and the red BRAKE warning indicator are fumed on.

DIAGNOSTIC AIDS
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 scan tool. The hydraulic control modulator test function of the scan tool may be used to locate an intermittent malfunction associated with the ESB.

NOTE: J 39200 test leads must be zeroed prior to making any resistance measurements.

After diagnosis is complete, clear the DTCs and test drive the vehicle for three drive cycles to verify that the DTC does not reset. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition off.