A051

DTC A051 Rear Motor Free Spins (Part 1 Of 2):

DTC A051 Rear Motor Spins Free (Part 2 Of 2):

DTC A051 Rear Motor Free Spins:

Circuit Description:
This DTC is designed to detect a stripped nut or gear assembly during initialization. During the homing sequence, the piston should reach the top of the bore resulting in a stalled motor. If this does not occur, the motor must be spinning with little or no resistance. This indicates a nut/screw or gear malfunction.

Failure Condition:
DTC AO51 can only be set during initialization. If the feedback current is less than the command current for a specified period of time, a malfunction exists.

Action Taken:
A DTC AO51 and a DTC AO86 are stored, ABS is disabled and the "ABS" and "BRAKE" indicators are turned on. The "ABS" indicator will flash if the EBCM cannot illuminate the "BRAKE" indicator.

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This step checks to see if the corresponding open motor DTC is also set.
2. This step verifies that the motor was actually applied as commanded by observing feedback current.
3. This step verifies that the motor can release.
4. This step verifies that the motor can be applied by observing pedal movement.
5. This step checks for a stripped gear on the motor pack.
6. This step checks for a stripped gear on the hydraulic modulator.
7. This step checks for a malfunctioning EBCM.
8. This step determines whether the motor pack has an internal malfunction.
9. This test checks for high resistance in the rear motor high circuit.
10. This test checks for high resistance in the rear motor low circuit.
11. This test determines whether the fault is due to a faulty hydraulic modulator or a faulty motor park.

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 TECH 1.

If the DTC only fails once and DTC A064 also fails, refer to DTC AO64. If intermittent and enhanced diagnostics show this DTC fails during ABS operation, refer to DTC AO64.

Depending on the frequency of the malfunction, a physical inspection of the mechanical parts suspected may be necessary.