Troubleshooting Trailer Wiring Where Taillights Partially Light Up When Engine is Off

Question:

2004 suburban 1500 v8 engine with toe-in package When engine is on, rear brake lights on car are dim. When engine is off, rear brake lights on car are bright cruise control has stopped working replaced multifunction switch and junction box at rear of car. did nothing to problem

asked by: Ed

Expert Reply:

You have a short in your trailer wiring. Most likely on the trailer side of the setup. You'd want to check the wiring and pins of the connectors looking for corrosion and/or damage and fix as needed. I suspect it's between the 12 volt power circuit and brake output most likely.

expert reply by: Jameson C