Trailer wiring warning

What you've got is a poor connection in the brake wiring. And it's about 50/50 odds on it being the truck or the trailer. Most often it is the connector at the bumper that gets wet or corroded.

It will be the brake system, not the lighting system. Your truck checks the brake system by monitoring resistance through the wiring. Intermittently it is not seeing the correct resistance. Either because of a poor connection, or because it is shorting to ground. You'll just have to find that bad connection, and you want to start at the bumper plug. Then work your way back to the brakes.

bobndot wrote:
I would check your TT plug.

controller is indicating a problem with continuity , often the wires become loose / dirty in the tt connector.

Yep, clean it and give the connectors a light polish with some emery cloth.

I would check your TT plug.

controller is indicating a problem with continuity , often the wires become loose / dirty in the tt connector.

If need be you could ask , if GM uses a scan tool to retrieve the codes from the DIC .

Very often this intermittant condition is caused by the cross over wires that travel thorugh the trailers axle tubes. They lay in there and eventualy start to rub through.

Wouldn't it be prudent to test the brakes when you get the warning light rather then waiting until you have to do an emergency stop with the warning light on and then finding out you got no brakes? I don't know what the answer to your issue is, but if it was me, I would sure want to know if my brakes were working when that warning light comes on.