Download UMOC Service Manual

Fault Diagnosis
Faults Related to Speed Sensor
Cable
The nine-pin speed sensor cable connects the motor to the
UMOC motor controller. Motor speed, direction, and
temperature values are reported to the microprocessor.
If the speed sensor plug is disconnected entirely, or, if one of
the wires inside the cable becomes broken, the motor will
continue to operate at very low rpm.
If the motor spins very slowly, or if vehicle speed will not
exceed one mile per hour, check the motor speed sensor
cable and observable diagnostics as follows:
9-Pin Encoder
(Speed Sensor)
Cable
RPM Indication:
Use the following procedures to determine if the motor speed
sensor has stopped functioning.
1. Jack up the drive wheels, and place the selector switch in
the off or neutral position.
2. Look at the “INFO” column of the user data screen. At
the bottom, you will see “rotor 0 rpm”.
3. Turn the drive wheels or the motor shaft slowly by hand.
If both drive wheels are off the floor, make sure only one
drive wheel turns. As the motor shaft begins to rotate, the
rpm display will change from 0 to nonzero rpm. If the
motor shaft is rotating and the rpm indication remains at
zero, the speed sensor has malfunctioned.
4. Check the sensor cable for loose connections or damage.
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CAUTION
Loose hair or clothing can
become entangled in
rotating parts. Also, be
sure to keep control cables
away from rotating parts
or driveshafts. Drive shaft
parts can snag on loose
cables, causing severe
damage