Pump Motor Fault

NAME OF CODE:
Pump/Motor Circuit Open

SET CONDITION:
The following criteria must be met for this code to be detected.
1. Ignition turned on for at least 3.4 seconds.
2. ABS power relay command given for at least 15 ms.
3. CAB pump/motor command never given during the current ABS power relay command.
4. Low feedback voltage from the low side of motor.
5. Criteria 1 - 4 satisfied for 30 consecutive controller checks spaced 5 ms apart.

THEORY OF OPERATION:
Whenever a power relay command is given and a motor command is not given, so that the motor should not be turning and generating a back-EMF, the motor winding can be considered a low impedance pull-up resistor. Consequently, the feedback voltage from the low side of the motor should be high. If it is not, and the problem persists long enough to rule out noise input, the (67) Pump/Motor Circuit Open code is set.

POSSIBLE CAUSES:
- Anything that keeps motor feedback voltage low when the power relay is supposed to be closed and the motor armature is supposed to be stationary
- Open motor winding
- Shorted CAB motor driver output
- Open circuit in series with the motor (excluding an open relay)
- Short to ground in the motor feedback to the CAB microprocessor




NAME OF CODE:
Pump/Motor Stalled

SET CONDITION:
The following criteria must be met for this code to be detected.
1. Ignition turned on for at least 3.4 seconds.
2. Valve, power relay, and motor (ignition cycle) self-test in progress.
3. ABS power relay command given for at least 15 ms.
4. CAB pump/motor command given for 500 ms and then turned off.
5. High feedback voltage from low side of motor continuously for next 100 ms.

POSSIBLE CAUSES:
- Anything that keeps motor feed back voltage high when it is expected to be driven low by back-EMF across the rotor winding of the coasting motor
- Seized motor or pump
- Open CAB motor driver output
- Shorted circuit in motor winding
- Short to a high voltage point in the motor feedback to the CAB microprocessor