2019 Denali Service Trailer Brake System

Hello all,

I’m sure this has been discussed, but it’s difficult to find.

2019 Yukon Denali 4WD 80k miles

I’m almost as a loss to stop the “Service Trailer Brake System” nuisance message to stop. I get it constantly and seems to be more prevalent when it’s cold and when I turn at slow/mid range speed.

I have cleaned the plug connection/let dry (it’s never been used before)

Blew out connections in trailer brake control module (looked clean to me)

Replaced trailer brake gain controller on the dash

Replaced both front ABS wheel speed sensors

I guess I’m about to replace the trailer brake control module and potentially maybe the rear ABS wheel speed sensors, but I’m not confident that will fix it so before I spend the money to do that, I am asking you experienced folk if there is truly a fix for this, or is it a gremlin that you live with because my research has given me zero confidence in the dealership to fix it.

Thanks

I had the same issue on my 2015 work truck. It ended up being the plug at the trailer hitch. I think they can hold water and cause corrosion internally. It happened twice under warranty. First was the module that is in the rear (dumb place for rain/salt). Second was the round 7 housing.