Curtis PMC Troubleshooting
Page 6
Control Wire Inputs
The voltage shown is for illustration
only. The actual voltage may vary.
_
+
Positive
Main Battery
Solenoids are shown for reference
only. The type of solenoid in your
truck may look different
REV
FWD
ISO
ISO
FWD
REV
_
+
Solenoids are shown for reference
only. The type of solenoid in your
truck may look different
The voltage shown is for illustration
only. The actual voltage may vary.
Connect a voltmeter across the Solenoid Negative Buss Bar
and battery positive.
•
If the voltage is not at battery volts then check the
wiring to battery negative and the negative circuit
breaker. Stop trouble shooting here and repair the
problem. When the repair is completed, completely
retest the vehicle before lowering the drive wheels
to the ground.
1. Make sure the key-switch is in the “OFF” position, then remove the key.
2. Place the forward-reverse switch in the center “OFF” position.
3. Set the park brake.
4. Place blocks under the front wheels to prevent vehicle movement.
The rear drive wheels may rotate during some of the following tests. Block the
front wheels, raise the rear drive wheels off the ground, and support the vehicle
with jack stands. Failure to do so may cause the vehicle to move and cause
severe bodily injury and/or property damage.
Rotating rear drive wheels are a potential hazard. Keep hands, arms, legs and
loose clothing away from the rear drive wheels while conducting tests. Failure
to do so may cause serious bodily injury.
Connect a voltmeter across the ISO solenoid coil terminals.
Close all interlock switches and turn the Key Switch
ON.
Depress the accelerator pedal to engage MS-1 only.
• If the voltage is not at battery volts then go to the
Key Switch
sequence.
• If the voltage is at battery volts and the ISO solenoid
does not pick up (click) then the ISO solenoid has
failed. Stop trouble shooting here and repair the
problem. When the repair is completed, completely
retest the vehicle before lowering the drive wheels
to the ground.
Note: Vehicles with Dana H12 transmission,
Forward solenoid is in the center.
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