Troubleshooting Wiring on a Trailer Towed by a 2005 GMC Canyon

Question:

I installed a TowReady T-connector into my truck wiring harness appears to be identical to 4-Pole Flat Trailer Connector # C55510 except for a name tag sticker referenced in a Q/A I read on the previous web page and I get all functions in my trailer lights. However, when the running lights are on and I turn on either blinker, not only does the blinker blink but the running lights blink as well not as bright as the regular turn signals, but a slight dimming as the blinker comes on. My ground wire from the T-connector is attached to the truck frame and I sanded the paint away so that it is against bare metal. I also have sanded the connections at the trailer ground points and reinstalled the screws using toothed washers as well. What can I try next? When I plugged the trailer into my 2012 Chevy Traverse I did not have any problem.

asked by: Don L

Expert Reply:

That definitely sounds like a weak ground that is causing your problem. You could check the condition of your hitch ball. Sometimes a rusty ball will affect how everything grounds on the trailer because the trailer also grounds through the ball to the frame of the vehicle. If the trailer has any type of folding coupler or dump function you might need to run a jumper wire to connect the two sections of the trailer.

It sounds like you installed the Tow Ready Wiring Harness # 118301.

I would also check the functions of the 4-way with a circuit tester like our # PTW2993. Check out the video I attached on how to test a 4-way to see how to do this. Hopefully you see the full 12 volts on all circuits with the vehicle running.

I would recommend you check for corrosion on the trailer connectors because it sounds like the turn signal/brake signal circuit could be shorting out on the tail light

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

expert reply by: Jameson C