Vehicle Tail Lights Stay On with Trailer Connected

Question:

I am working with a 1998 Dodge Ram pickup with a 8foot flatbed installed for shop work. We have a gooseneck hitch installed to pull the 5th wheel. We bought an adaptor for the wiring to work with the 5th wheel. When I plug in the adapter from the truck to the trailer, my tail lights on the truck are always on. When it is running, to when just the keys are in it, to no keys in it and it is locked up and shut down. Still my tail lights on just the truck stay on. With this, the brake lights do not initiate on the trailer as well. All of the lights work tail lights, signals, etc. on the trailer except the brake lights. I have a feeling that there is a connection with the lack of brake lights on the trailer and my tail lights constantly staying on on the truck. Any thoughts or suggestions would be appreciated. Please help!

asked by: Kyle

Expert Reply:

It sounds like the pins inside the trailer connectors on the vehicle and trailer do not match. I have attached a photo of the two most common ways to wire a 7-way trailer connector, whichever way you choose the trailer side will need to match the vehicle side and vice versa. Please note that determining the function of a wire must be done through the use of a circuit tester, not color matching.

expert reply by: Conner L