Troubleshooting Haulmark Trailer Right Brake Light

Question:

i hooked up my trailer to my 2003 suburban 1500, all the lights are working except the brake light on the right side. Any suggestions?

asked by: Kevin N

Expert Reply:

Since trailer wiring uses one common circuit for both right-hand brake lights and turn signals it is possible that you have a bad bulb in your light fixture. This is easy to check and the cost to replace a bulb is minimal.

If you have a circuit tester like # PTW2993 you can test the connector on the vehicle to see if the correct brake light signal is present there. Have a helper step on the brake pedal while you apply the probe of the grounded tester to the pin for the right brake light. This is the 7-way contact at the 3:00 position. You can refer to linked photo to see the position of this contact. If your tester detects the correct right brake signal on this pin, then you know the issue is on the trailer side.

In that case check the trailer wiring for the affected light, especially the ground connection which should be made to clean bare metal. Sometimes a grounding point can develop corrosion and all you might need to do is unscrew a ring terminal and sand off that spot. You can then protect that good new connection with dielectric grease # 11755.

expert reply by: Adam R