With Turn Signal and Brake Lights On All Trailer Lights Flash when Connected to 2007 GMC Yukon

Question:

I have a 2011 Trail Master trailer made by US Cargo and I pull it with a 2007 GMC Yukon when I put the turn signal on left or right and step on the brake all of the lights flash. The Yukon and Trailer both have a 7-way connectors . How can I fix this ?

asked by: Roger

Helpful Expert Reply:

It sounds like there may be a ground problem or a possible overload. Ground problems and overloads normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

If the trailer using incandescent lights then it is possible that there is too much power draw for the tow package on the 2007 GMC Yukon. To determine if this is the case you can disconnect some lights and if everything starts working then it was either an overload situation or a problem with one of the lights that was disconnected.

Switching to LED lights will reduce the draw on the system and would solve the overload issue.

expert reply by: Michael H