Troubleshooting a Trailer Third Brake Light with Tail Light Converter  

Question:

Expert Reply:

I'm sorry to hear you are having trouble installing your third brake light. The number one culprit in this situation is not having a good ground connection. The white wire on the input side of tail light converter # 118158 should be grounded to a suitable location on the trailer frame. Make sure that any paint is sanded off the grounding location and that there are no shorts in this wire.

If your ground is good, you'll need to inspect the wiring on the trailer. You can use a lighted circuit tester like # PTW2992 to check the input and output wires on the converter. If power is going in but no power is coming out, the converter is probably bad. If power is going in and coming out of the converter, then the light itself may be defective. Follow each wire to its end and check for any damage, fraying or shorts in the wires. The green input wire should tap into the right turn circuit on the trailer. The yellow input wire should tap into the left turn circuit. The output side of the converter also has 3 wires. The yellow and green wires should be taped off with some electrical tape and secured out of the way. The red output wire will connect to your third stoplight with the light also grounded to metal on the trailer frame. See attached wiring diagram. I've also provided a video showing how to use a circuit tester to test wires on a converter if you are unfamiliar with that process.

Please let me know the results of your troubleshooting. I'm happy to answer any further questions you may have.

expert reply by: Amy W

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