“Service trailer brake system” message

[Icutmetl]

I saw the “service trailer brake system”  message pop up on my information center; not sure why that would be.

 

A little background on how my day with this truck has been...

 

Driving from Ohio to St.Paul in my 2018 GMC 2500HD. Had a bit of gelling happening early in the trip where it was shuddering when applying power, so I pulled into the next Pilot station & added both another 16oz of Power Service white bottle, as well as their emergency red bottle stuff. That fixed it right away. Stopped in Wisconsin Dells for lunch; shit the truck off for 1/2hr or so, and it started really funny. Like it cranked hard, almost. It fired up and sounds normal, and I’ve shut it off and re-started a couple times without issue. What I keep seeing though is the “service trailer brake system” message pop up. I’ve never used the trailer brakes yet; only a 4-pin on a small trailer about a month ago.