Troubleshooting Left Taillight Circuit Not Activating After Checking Grounds and Replacing 4-Way

Question:

The left taill light doesnt work. The turn signal and brake lights both work though. I replaced the four prong trailer wire connector, the left tail lite and also cleaned the g round connection.

asked by: Duane D

Expert Reply:

Somewhere on the running light circuit on the left side of the trailer there is a short. It sounds like you have started at both ends of the trailer by replacing the 4-way and checking the ground of the light assembly. So its time for you to check what lies between the connector and the assembly; the wiring.

If you have a wishbone wiring system where two wire come out of the running light circuit on your 4-way then you need to trace the wiring from the connector all the way back to the assembly looking for any cuts in the wire and fix as necessary. If there is only one wire coming out of the running light circuit of your 4-way you need to trace that wire back to where it tees off and then check the wiring that runs to the left tail light assembly.

I attached an FAQ article on trailer wiring for you to check out also.

expert reply by: Jameson C