Testing Options for 7-Way of Trailer for Function

Published 10/22/2019

Question:

I have a 2015 Chevrolet Silverado 2500. I was pulling my dump trailer today and was told my right side stop/turn signal wasnt working. I pulled the light out, had it tested, both sides of the light work. My trailer harness doesnt stay connected to the truck plug very well, to me the plug on the truck is upside down. I would think the flap should be on top and the weight of the trailer harness and wire would hold the bottom blades of the trailer harness tight against the trucks plug, instead the top half of the trailer harness wants to pull away from the trucks plug causing a weak/loose connection. I took a tarp strap, hooked it to the top of the bumper, ran it around the trailer wiring harness forcing the top of the harnesses plug to seat against the trucks connector. This still didnt allow the light to work. The tail side works, the stop and turn doesnt. According to the wiring diagrams I have seen the two blades that dont make a good connection are for the brakes and the ground, all other lights work ok so the ground should be making connection. So, long story short, I dont know if I have a problem with the truck or the trailer. I was looking for a tester that would test both. I found a tester for the truck side but not finding one for the trailer side, unless the tester I saw can do both, any insight into my issue would be greatly appreciated.

asked by: Todd R

Expert Reply:

We have circuit testers that work on the trailer side of the wiring like the # 8010 but since they have to send power to the circuits and verify that the circuit is complete they are a bit more involved than the testers that fit into a 7-way like the # TR20117.

Another solution is to run a jumper wire from the positive pin of a vehicle battery to each of the pins on your trailer 7-way and then watch to see if the circuit activates. I attached a 7-way diagram for you to check out as well.

expert reply by: Jameson C