center of the steering wheel. Refer to figure 4-4 for troubleshooting. In testing the horn circuit, first find the horn relay. Normally, it is mounted under the hood in the engine compartment. Next, check for voltage at terminals B, ING, and SW. If voltage is present at the relay, switch the probe to terminal H and depress the horn button. If the test lamp lights, the relay is good. Check the horn.
Small accessory motors are used to drive cooling and heating fans, windshield wipers, fuel pumps, and so forth. Since most of these motors are basically the same, troubleshooting is reasonably simple. The hardest part may be getting to the motor. Normally, troubleshooting procedures are as follows:
1. Check the fuse.
2. Turn the motor by hand when possible. Some obstruction may be causing it to jam, over- loading the circuit and blowing the fuse.
3. Check for power at the last multiwire connector going to the motor. Be sure power is arriving at the motor.
4. Look for burned wiring and loose connections. Burned insulation will be discolored and will smell burned.
5. Troubleshooting of small electrical accessory motors is similar to continuity and ground tests performed on starting motors mentioned earlier in this chapter.
6. Repair the motor according to manufacturer's specifications.
Construction Mechanic 1, Naval Education and Training Program Management Support Activity, Pensacola, Fla., 1989.
Crouse, William H., Donald L. Anglin, Automotive Mechanics, 9th ed., Gregg Division, McGraw-Hill Book Division, New York 1985.
John Deere Fundamentals of Service, Electrical Systems, John Deere Service Publications, Dept F, John Deere Road, Moline, Ill., 1984.
Special Vehicle Mechanic, Extension Course Institute, Air University, Gunter Air Force Station, Montgomery, Ala.
U.S. Army TM 9-2320-209-20-1, Organizational Maintenance Manual for 2 1/2 Ton 6X6 Trucks, Department of the Army, Washington D.C., 1978.
U.S. Army TM-9-8000, Principles of Automotive Vehicles, Department of the Army, Washington D.C., 1985.Continue Reading