Troubleshooting Trailer Taillights on Passenger Side of Trailer that Dont Function

Question:

I have trouble with passenger lights on my trailers so I know its not the trailer. I have a 02 f150 super crew and the problem is when I use the round connector for the lights. Any suggestions which color wire controls that side? Is it in the plug or wires? I have used electronics cleaner and cleaned the socket and there is no corrosion. Thanks for any help!!

asked by: Kevin L

Helpful Expert Reply:

Sounds like you have ruled out corrosion as the problem since you have cleaned the socket on both your truck and your trailer. The only way to completely rule out the truck as the problem though would be to use a circuit tester like our part # PTW2993 to test all of the pins on the truck's connector. For more info on how to do this check out the video I attached to the right.

To see the functions of all of the pins on your 7-way check out the diagram I attached to the right.

If the truck connector isn't functioning correctly check the back of it for cut or exposed wire and fix as necessary.

Most likely when one side of a trailer's lights stop functioning the problem is ground related on the taillight assemblies. Check the passenger side trailer light assemblies and make sure they are connected to a clean metal surface.

I also attached an FAQ article on troubleshooting 4-ways for you to check out as well.

expert reply by: Jameson C