Trailer Turn Signals and Brake Lights Not Working on a Boat Trailer
Question:
i bought a boat and the tail lights work on the boat but i cant get the turn signal or brake lights to work i have a factory connector a 7 blade and a 4 prong right next to it i have power to the the main connector that goes to the lights on the truck but not coming down to boat plug could the harnass and plug connection be bad im frustrated i bought all new plugs for the truck and still dont work what could this be
asked by: Todd
Expert Reply:
If you are getting the correct signals from the truck side trailer connectors, then the problem is on the trailer. There could be a number of issues causing the problem. The easiest to check would be the trailer side connector. With the trailer connected, test the wires right behind the trailer side connector using a circuit tester like # PTW2993.
If no signals are coming through, then you know the connector is bad and it will need to be replaced. While you are at the trailer side connector, check for any corrosion or dirt in the connector and clean it out thoroughly. If you are still having problems, make sure the main ground wire from the trailer side connector is attached to a clean and corrosion free bare metal surface on the trailer frame.
You can then go on to test the wiring working your way back to the tail lights. If there is a break in the wiring anywhere, that can be causing the problem. Next you can check the tail lights. Trailer tail lights usually ground through the mounting studs if no obvious ground wire is present. In both cases, the ground or studs need to be attached to a clean and corrosion free bare metal surface. If a plastic license plate is between the light and the trailer, that, too, could be causing problems.
Most likely you are experiencing a bad or missed ground, a dirty connector, of the trailer side connector is wired differently than your truck side trailer connector; or it could be a combination of these. The good news is that even though troubleshooting the problem takes some time, the fix for each of these issues is pretty easy.
Another possible issue is depending on the year, make, and model of the truck, you may need relays and/or fuses to make the towing package fully functional. You can check your owners manual to determine if fuses and/or relays are used and where to check for them in the power distribution box under the hood.
Products Referenced in This Question
Product Page this Question was Asked From
Plug-N-Tow (R) Vehicle Wiring Harness
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- No Converter
- Custom Fit
- 4 Flat
- Hopkins
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Jerry
7/27/2020
I had an issue with my trailer lights were only the running lights would work but turn signals and break lights wouldn’t. I replaced the entire harness and upgraded to LED lights. Every light is connected properly with their respective ground. When I tested it with the truck it does the same thing the old lights did, only running lights but no signals or break lights. Then I replaced the truck harness for a new one, same issue, I checked the fuse panel on the truck and all fuses are good. Can’t think in any other thing.