Trailer Clearance Lights Blinking with Turn Signal


I have 2006 GMC HD2500 and usir to haul several trailers. One is 5th wheell, two cargo trailers, and a boat trailer.. The 5th wheel uses a 7-pin connector. The other trailers use a 4-pin flat adapter to the same truck 7-pin. Ive pulled all 3 for several years with no problems. Recently I noticed the older carge trailer clearance and tail lights flicker when either turn signal is on. I then noticed the same thing on the 5th wheel. However, on the boat trailer they seem to work fine. I have checked the ground as best I could. Even wirined temporarily directly from battery to trailer body. Still flickers. Any suggestions?

Expert Reply:

It sounds like you might be getting some bleed-over from the turn signals occurring in the trailer connector. Take a look at the trailer connector, and check the plug for corrosion in the sockets. If you see any green or white corrosion in the sockets, then there is a good chance it has spread to the interior of the connector, to where the wires attach to the plug terminals. Once this corrosion starts building up, it can actually contact adjacent terminals and cause signal bleed-over. You would also want to check the adapters for corrosion, as well.

You can also make sure that the trailer connector on the vehicle is properly grounded. Make sure the connection is tight and not corroded.

I have linked you to a trailer wiring troubleshooting FAQ article that you might find helpful.

expert reply by:
Michael L

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