Yet Another Trailer Problem

[Frank Iaccino]

I have been lurking about for some time, but this is my first post. I've had this 2021 RST for about a month and have a really weird trailer issue. I have three trailers, one with one axle, two others with two axles. NONE of them respond to the factory installed brake sender. The previous truck/trailer combination never had an issue. The prior truck was a 2017 Silverado with factory installed brake sender. All trailers have all properly working lights when connected to the new truck. We pulled another Chevy 1500 (with an aftermarket sender) up to each of the trailers and all have trailer brakes working. Seems to me, the problem is with my truck, right? I took it in to the Service Dept. and the used a 'trailer simulator' to test the brake sender and found no issues with the truck, but when the trailer was attached, they found problems like, "Service Trailer Brakes". While driving home, I thought I should try one more time and test my truck on someone else's trailer, just to make sure. When I plugged his trailer into my truck, all was good. My truck was sending the correct brake signal to his trailer. ???? It gets better. I then plugged both of my two axle trailers into my truck and now they work properly also. The one axle trailer still has no braking from my truck. Any ideas??  Thank you in  advance.

 

Frank