Turn Signal Lights Freeze when Trailer Is Connected to a 2010 Ford F-150

Question:

I have a 2010 f 150. When i plug in trailor lights it freezes my turn signals. Why is this

asked by: Jake

Expert Reply:

It sounds like there is either a short circuit causing constant power draw or back feeding, or the truck connector and trailer connector are wired differently, and the turn signal issue is a result.

To determine where the problem is you can plug in a different trailer and if the same issue happens then there must be an issue with the truck tow package wiring. If it does not happen, then the issue is on the trailer.

You can test the truck connector with a circuit tester # PTW2993. Have someone sit in the truck and go through the various functions while you test the connector. If the same problem occurs when testing and no trailer connector, then there is some issue on the truck that will need to be addressed. Check for dirt and corrosion inside and outside of the connector and clean as needed. Make sure the wire connections are all secured.

If the problem only happens when a trailer is connected, then the issue must be on the trailer. Make sure its connector is clean and corrosion free. Then make sure the main trailer connector ground and the grounds for all the lights are attached to clean and corrosion free bare metal surfaces.

Inspect the trailer wiring for any breaks with bare copper strands touching bare metal. This can cause a short and subsequent constant power draw. I have included some links to FAQ articles that can help.

expert reply by: Michael H