Trailer brakes stuck on 07 KW T600 | TruckersReport.com Trucking Forum

So the brake light fuse and relay made no change, but ABS relay made the lights go out?

That would make me wonder about the ABS module backfeeding down the brake light sense wire.

Have the trailer slider lines possibly been drug and possibly damaged the wiring to the module.

Which pins on the 7 way were hot?

Center pin is ABS +, bottom center brake lights