Chevrolet Colorado & GMC Canyon Forum banner

Brake lights on trailer not working.

94 Views 1 Reply 2 Participants Last post by  cart7881
2005 colorado with. 7 pin trailer plug installed when I got it. Just rewired my boat trailer and all the lights are working except the brake lights. I’m not getting power at the plug when the brakes are pressed. Under the truck bolted to the hitch is a black module of some sort. Has 5 wires going in but 4 coming out. The extra wire is light blue.

So my question is, what is the module? Is it factory? And can it be bypassed?
1 - 2 of 2 Posts
I don't have the tow package, so this info is coming from the 2005 Colorado Service Manual, not hands on experience.

The OEM trailer connector is a four wire plug. The five inputs to the OEM converter box are: White=ground, Yellow=lt turn, Green=rt turn, Brown=park lights, Blue=stop lights. The schematic shows four output wires going to the trailer connector: Yellow=lt turn/stop lights, Green=rt turn/stop lights, Brown=park lights, White= ground.

I have heard of 7 pin connectors mentioned before, but I don't have any idea if it was OEM or aftermarket. The Service Manual only has info for a 4 pin connector.

As for bypassing the converter box, that is a good question. If the above info doesn't help, maybe you could splice into the input harness and pick up the brake light signal (Blue wire). Not sure what, exactly, is inside the converter box or what it does.
1 - 2 of 2 Posts