Troubleshooting Trailer Light Functions When Connected to 2005 Chevy Colorado
Question:
Hi, Im having a problem I can figure out. My trailer has a 7 pole plug on it. So I bought a flat 4 pole to 7 pole adapter so I didnt need to do any modifications except adding a brake controller for the trailer brakes. Before I install the controller I noticed the brake lights and turn signals wont work while the headlights or running lights are on in the cab. If I turn the auto light switch to the off possession the brake and turn signal lights work on the trailer. I just installed a new Curt custom wiring harness # 55510 thinking that was the problem. Still doing the same thing. If the running lights day running lights are on the running lights work on the trailer but no brake or turn light.... What would cause this problem. Ive been pulling out what little hair I have left trying to figure this out. Thanks for anything you can do to point me in the right direction....
asked by: Tom M
Expert Reply:
Most often when one trailer lighting function works until another function is activated the cause is a bad ground. A weak or loose ground connection will limit the amount of current that the harness can deliver to the trailer connector. We mostly see the issue show up once the running lights are turned on. Since running lights remain on continuously they will draw more current than circuits like brake or turn lights that blink or that are on only momentarily.
Make sure the white ground wire's ring terminal is tightly attached to a clean bare metal surface, free of paint, primer, rust, grease, etc. Also check that your adapter's ground pin is making full contact. You might also want to check that your trailer's total power draw is not more than the maximum that can be delivered by the Curt harness # C55510, which can output up to 3-amps on the stop/turn circuits and 5-amps on the running light circuit.
