Antilock Braking System (ABS)

Code 51: Rear Motor Free Spins (Part 1 Of 2).:

Code 51: Rear Motor Free Spins (Part 2 Of 2).:

DTC 51 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, indicating a nut/screw or gear malfunction.

DTC Will Set When:
DTC 51 can 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 malfunction DTC is stored, ABS is disabled, and the ABS indicator lamp is turned "ON."

DTC Chart Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Compares feedback current to command current during apply.
2. Compares feedback current to command current during release.
3. Moves the piston to the top of the bore.
4. Checks for excessive resistance in the rear motor high circuit.
5. Checks for excessive resistance in the rear motor low circuit.
6. Checks for resistance in the rear motor.
7. Checks for a stripped motor pack gear.
8. Checks for a stripped hydraulic modulator gear.
9. Checks for proper operation of motor pack.
10. Checks for proper operation of the hydraulic modulator.
11. Ensures malfunction was not due to poor terminal contact.

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 DTC only occurs once and DTC 64 also occurs, see DTC 64. If intermittent and enhanced diagnostics show DTC 51 occurs during ABS, see DTC 64.

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