Troubleshooting Turn Signals and Brake LED Lights On Boat Trailer

Question:

I have a small boat trailer with A 4 pin connection going to wishbone wiring on the trailer. I have the marker lights, running lights, and both the signals however NO brake lights. And the turn signals won’t work if the running lights are on. The lights are LED relays installed by the person I bought the boat from. Have checked my grounds and added a jumper ground between the two rear lights but that did not fix anything Thanks!

asked by: Evan

Expert Reply:

Your issue definitely sounds like a classic ground issue, but you said you checked those already. My next thought is an overload but that's not very likely with LEDs unless you have a short causing it.

Trace the wiring using a circuit tester, like part # PTW2993, to see if you can isolate a location that loses the power. If it starts at the connector than the issue on your tow vehicle and you should check its ground point as well. Also make sure the connectors are clean of any corrosion.

expert reply by: Timothy G