4 Answers

Bad ground wire.

13 years ago. Rating: 1
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Damaged wire, or blown fuse.

13 years ago. Rating: 1
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resistance in the supply causes a drop in voltage and lower output from the lights. Most problems i have repaired result from bad ground trailer to vehicle connection. If trailer has no breaks get a brake connector plug and connect the lights like the directions provide, but use the brake connector to connect ground to trailer and vehicle. After this check voltage again. May be finished, but if not this will eliminate many problems later. Resistance can be caused in a trailer either by dirt/corrosion or whatever in either the plug or the crimp connections to the various light holders. I start at the battery, to establish the line voltage. Then go to the trailer light plug on the car to test voltage. (Run a jumper to the negative post of the battery to do the tests.) If line voltage still low , then start dividing in half the line from the trailer plug to the lights at the end of the trailer then test voltage with the trailer plug on and the lights on.
If you find a splice that shows voltage drop before and after the connection, it is bad, replace. If the splice shows the drop there could be a partial break inside the wire between the trailer plug and the splice. Do same test on the other leg of the wire from splice and lights. It is also possible to have voltage loss inside the light housing. ****************
If none of these tests work, I have solved the problem by buying a simple relay form AutoZone and used the trailer plug lead to turn on the relay(like a switch) then run a fused line to the car battery positive post. Still have to ground the relay and the lights well. I have even done this relay box thing to solve fuse blowing problems that result from the trailer wiring pinching against the ground. It is easier to trace a single fuse at the battery than the whole vehicle and the inline fuse is cheaper as well if it happens often. Have to place the relay wiring into a dry box for long term use. Home depot sells them in the electrical section. Hope this helps

13 years ago. Rating: 1
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BROKEN WIRE USUALLY AT PLUG OR AT MAIN SPLICE

13 years ago. Rating: 1
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