Usage:
Once all connections have been checked, energize the system. Turn the retarder ON/OFF switch 'ON'. If the retarder fails to operate, check all connections again. If the retarder still does not operate correctly, follow the step-by-step procedure that follows.
1. Measure the voltage on the RED wire. Put the (+) probe on the red wire, and the (-) probe to ground. The VOM should read +12 volts.
2. Measure the voltage on the ORANGE wire. Put the (+) probe on pin D of the 6-way Weather Pack connector and the (-) probe to ground. The VOM should read (+) 12 volts.
3. Put the selector switch in LO, and measure the voltage at the purple wire. Put the (+) probe of the VOM on the purple wire, and the (-) probe to ground. The VOM should read (+) 12 volts.
4. Put the selector switch in MED, and measure the voltage at the gray wire. Put the (+) probe of the VOM at the gray wire, and the (-) probe to ground. The VOM should read (+) 12 volts.
5. Put the selector switch in HI. Put the (+) probe on either the YELLOW or BLUE wires, and the (-) probe to ground. Next, if the vehicle being used has an optional vehicle module, ensure that the cruise control is OFF. Next, ensure that the clutch pedal is up. With the vehicle in neutral, increase the engine speed to the engine rated rpm, and then release the throttle. The VOM should read (+) 12 volts when the engine speed is above 950 rpm. If it does not, ensure that the output wires are not shorted, and a good connection is made. If the VOM still does not read (+) 12 volts, on either the BLUE or YELLOW wires, replace the control module.
6. If the control module still does not operate when replaced, then the problem is probably with the interface signal provided by the Caterpillar ECM (electronic control module).