Troubleshooting Brake Light/Left Turn Signal on a Trailer Towed by 1999 Chevrolet Silverado

Question:

99 Silverado replaced plug on truck for the trailer. this not a factory plug.the truck has a tow package not the plug just wires.i put a Hopkins #48055 plug on.matched the colored wires and tested them.have running lights and right side blinker but no left blinker and no brake lights

asked by: James

Expert Reply:

The first thing I would test is the trailer connector on your 1999 Chevrolet Silverado using a circuit tester like part # PTW2993 to see if the problem lies in the trailer or in your vehicle. See the linked video to see how to do this. You will be testing for brake/stop light functionality of the circuit and this will tell you if the problem is on the truck or the trailer. Also, to ensure that your trailer connector is wired properly, we recommend using the circuit tester to match pins by function. Because wire colors can vary, they are not as reliable for determining functions. And improperly connected wiring can cause damage to electric components.

If the problem is on the truck, I'd check the fuses and relays of the tow package and replace as necessary.

If the problem is on the trailer, I would inspect the turn signal/brake light circuit wiring to see if some corrosion or exposed wire is causing the problem and fix as necessary. I would first start at the trailer connector and check for corrosion there and then go back to the tail light assembly and check for corrosion or anything else that would prevent the brake/turn signal from operating.

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

expert reply by: Chris O