Electrical Troubleshooting

Two basic tools are essential for troubleshooting electrical problems: a wiring diagram and a 12-volt test light. A test light is an inexpensive little tool that looks like a cross between an ice pick and an electric screwdriver. Simple to use, it is connected by its clip to a ground. The sharp probe is poked around the hot leads. If the lamp lights, there’s power, at least to that part of the circuit. For example, clip the test light to a bumper bolt or other good ground and touch the probe to a bulb contact on the hot side—the bulb will light, so long as the light is on.

Most lamp problems are conveniently found in the lamp unit itself. The great majority are caused by bad bulb contacts or corroded grounds. Don’t assume that there are major problems until the non-functioning unit is completely inspected. Using the wiring diagram, work your way back through the circuit to the connectors, and from there to the source of power, such as the fuse box or terminal connector. By this method, you should be able to determine whether an entire circuit or the individual unit is at fault. If the circuit is dead, track the problem from the fuse box or battery side of that particular circuit. Proceed through the circuit components one at a time, using the wiring diagram as a guide. Don’t panic!