DTC A066: Rear Axle Motor Circuit Short to Batt or Motor Short

REAR AXLE MOTOR CIRCUIT SHORTED TO BATTERY OR MOTOR SHORTED





Circuit Description
This DTC identifies a motor circuit that is shorted to the battery or a motor that has low or no resistance. This malfunction will prevent the motor from being controlled at the commanded current rate or will cause the motor to turn in the opposite direction or not at all.

Diagnosis
This test will detect a short to the battery in the rear axle motor circuitry.

Cause(s)
- There is a short to battery in the wiring from the electronic brake control module (EBCM) to the motor.
- The motor armature winding has low/no resistance.
- The EBCM is malfunctioning.

Fail Action
This is a critical operational fault. The ABS is disabled and the ABS warning lamp is turned on. A rehome is commanded on the other two channels to ensure that they are in the home position. The brake warning lamp is also turned on if the rear axle piston is not in the home position.

Test Description
The number(s) below refer to step(s) on the diagnostic table.
3. This step checks for a short to voltage in the motor feed circuitry.
4. This step checks for a short to voltage in the motor return circuitry.
5. This step checks for a motor that is internally shorted.

Diagnostic Aids
Select the manual control function of the scan tool to exercise motor movement of the 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 a RELEASE function on the motor, an intermittent malfunction may be indicated.
An intermittent malfunction may be caused by a poor connection, wire insulation that has been rubbed through, 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 the connections.
Check the frequency of the malfunction by using the enhanced diagnostic feature of the scan tool as described in "Scan Tool Diagnostics." Scan Tool Diagnostics
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.





DTC A066 - Rear Axle Motor Circuit Shorted to Battery or Motor Shorted