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Short Circuit Inside a Wire Harness
A common occurrence inside of wiring harnesses is that there are two wires running close and parallel to each other. One wire is the positive
wire that flows one way and the ground wire that flows back the opposite direction. When the signal source runs closely parallel to the signal
return, as in this case, they cancel each other and the signal strength is considerably reduced.
You can pull one wire at a time away from the other wires, creating some distance between them. As you hold the wire away from the other
wires, the signal canceling effect is removed in that area and the signal strength will increase in the wire. You can now get a reading off of the
wire with the receiver by holding it parallel to the receiver’s pick-up area. Take note of the directional indicator of the receiver. Check for the
other wire that indicates the opposite direction. You can now assume that both wires are in the same circuit. Trace both wires as a pair along
the harness until you find the problem. (see illustration)
