C1254

Circuit Description
DTC C1254 diagnoses an ABS motor that energizes longer than expected. The following conditions may cause the longer period of being energized:
^ A wheel speed sensor malfunctions.
^ The ABS motor does not turn.
^ The ABS brake motor wires cross.

Conditions for Setting the DTC
DTC C1254 can only set during an ABS stop.
A malfunction exists if the EBCM commands the rear ABS channel in release for greater than three seconds.

Action Taken When the DTC Sets
^ A malfunction DTC stores.
^ The ABS disables.
^ The ABS warning indicator turns ON.
^ A rehome is commanded to ensure the motors are in the home position.

Conditions for Clearing the DTC
^ The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTCs function is used.
-^ 00 drive cycles pass with no DTCs detected. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition OFF.

Diagnostic Aids
The following conditions may cause an intermittent malfunction if the conditions exist in a mechanical part of the system:
^ Sticking
^ Binding
Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction. Use the Scan Tool hydraulic test in order to ensure the total brake system is functional.
Thoroughly inspect any circuitry that may be causing the intermittent complaint for the following conditions:
^ Backed out terminals
^ Improper mating
^ Broken locks
^ Improperly formed or damaged terminals
^ Poor terminal-to-wiring connections
^ Physical damage to the wiring harness
Clear the DTCs after completing the diagnosis. Test drive the vehicle for three drive cycles in order to verify that the DTC does not reset. Use the following procedure in order to complete one drive cycle:
1. Start the vehicle.
2. Drive the vehicle over 16 km/h (10 mph).
3. Stop the vehicle.
4. Turn the ignition switch to the OFF position.

Test Description
4. This test checks for a wheel that may stick or bind because of a mechanical fault.
5. This test ensures that the motor is capable of moving and applying the hydraulic piston for the rear wheels.
6. This test ensures that the motor wiring is not crossed.
7. This test isolates the malfunction of a no apply situation to either the motor pack or the hydraulic modulator.








DTC C1254 Rear ABS Channel in Release Too Long