C1257

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(Part 2 Of 2):

CIRCUIT DESCRIPTION
This DTC identifies a motor circuit that is shorted to ground. An uncontrollable motor will not allow controlled ABS operation.

CONDITIONS FOR SETTING THE DTC
DTC C1257 can be set anytime. A malfunction exists if the EBCM detects an out of range voltage in either of the left front motor circuits indicating a circuit shorted to ground.

ACTION TAKEN WHEN THE DTC SETS
A malfunction DTC is stored, ABS is disabled, and the ABS indicator lamp is turned ON.

CONDITIONS FOR CLEARING THE DTC
Conditions for the malfunction are no longer present and the scan tool CLEAR DTCs function 1S used. One hundred ignition switch key cycles have passed with no malfunctions detected.

DIAGNOSTIC AIDS
Using the scan tool, select MANUAL CONTROL function, and exercise motor movement of affected channel in both directions while applying light pressure on the brake pedal.

If erratic or jumpy brake pedal movement is detected while performing an APPLY or RELEASE function of the motor, an intermittent malfunction may be indicated.

An intermittent malfunction is most likely caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.

If the malfunction is not current, wiggle the wires of the affected channel and check if the DTC resets. This will help to pinpoint an intermittent malfunction in the motor circuitry or connections.

The frequency of the malfunction can be checked by using the ENHANCED DIAGNOSTIC function of the scan tool.

Any circuitry that is suspected of causing the intermittent complaint should be thoroughly checked for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.