Troubleshooting No Right Brake Light on a Trailer Towed by a 2001 Chevrolet Silverado

Question:

all other lights and blinkers work correct, but the break light on the right side of the trailer will not work. all vehicle lights work right. could it be that my 2001 chevy break light signal and blinker light are separate?

asked by: Ryan

Expert Reply:

The turn signal and brake light circuits on your 2001 Chevrolet Silverado are separate and trailers typically require a combined turn signal and brake light circuit because they only use one bulb for both functions at the tail lights.

If you have a factory installed wiring harness on your truck, these circuits should already be combined at the trailer connector. If this is the case, then the issue may likely be a poor ground connection on your trailer. I recommend checking the ground connections for the right brake light on your trailer as well as the ground for your trailer connector.

If you have an aftermarket wiring harness installed on your truck, then I recommend using a circuit tester like part # PTW2979 to test the functions of each pin. If you have a 4-way flat trailer connector, then you can test the pin on the opposite end of the exposed ground pin (see photo). If you have a 7-way trailer connector, then you will want to test the pin in the 3 oclock position (see photo).

If you have power for the right brake light at the vehicle side trailer connector, then we know the issue is on the trailer. As I mentioned above, this issue is typically caused by a poor ground connection on the trailer.

If you do not have power for the right brake light at the connector, then there is an issue with the trailer wiring on your truck. This could be caused by loose wire connections or a poor ground for the trailer connector.

If you are unable to find the problem or a solution, let me know what you come up with and we can take further troubleshooting steps. I have attached an FAQ article on trailer wiring for you to check out. This should be helpful when troubleshooting the wiring on your trailer.

expert reply by: John H