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
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:
Check the fuse.
Turn the motor by hand when possible. Some
obstruction may be causing it to jam, over-
loading the circuit and blowing the fuse.
Check for power at the last multiwire connector
going to the motor. Be sure power is arriving at
Look for burned wiring and loose connections.
Burned insulation will be discolored and will
Troubleshooting of small electrical accessory
motors is similar to continuity and ground tests
performed on starting motors mentioned earlier
in this chapter.
Repair the motor according to manufacturers
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,
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