C1251

Circuit Description
DTC C1251 detects a stripped nut or gear assembly during initialization. During the homing sequence, the piston should reach the top of the bore. Then the ABS motor stalls. If the ABS motor does not stall, the ABS motor must be spinning with little or no resistance. This indicates a nut/screw or gear malfunction.

Conditions for Setting the DTC
- DTC C1251 can only set during initialization.
- A malfunction exists if the feedback current is less than the command current for a specified period of time.
- This DTC can be set during motor re-home.

Action Taken When the DTC Sets
- A malfunction DTC stores. A corresponding DTC C1286 will also set.
- The ABS disables.
- The ABS warning indicator turns ON.
- The red BRAKE warning indicator turns ON.

Conditions for Clearing the DTC
- The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTCs function is used.
- 100 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
An intermittent malfunction in this DTC may result from a mechanical part of the system that slips, such as a stripped gear or a backed off gear retaining nut.
Depending on the frequency of the malfunction, a physical inspection of the mechanical parts suspected of causing the malfunction may be necessary.

Test Description
3. This test checks for motor movement by comparing the motor feedback current to the motor command current during application.
4. This test checks for motor movement by comparing the motor feedback current to the motor command current during release.
5. This test checks for piston movement.
6. This test checks for excessive resistance in the rear motor high circuit.
7. This test checks for excessive resistance in the rear motor low circuit.
8. This test checks for the correct resistance value of the rear motor.
11. This test checks for correct operation of the motor-pack assembly.
12. This test checks for correct operation of the hydraulic modulator.
14. This test determines if the malfunction is caused by the EBCM.