Check trailer lights

[Toomas]

Have 2020 DenalI 2500 HD, have always had a problem with "trailer disconnected" warnings when pulling 5th wheel, but solved that problem by pushing 7 pin in further, so ok. Now though I disconnected my trailer and get same messages(and NO trailer is attached) and also blinkers are very fast. Any ideas?

[shadow gray 2020 hd]

I have had similar issues, while driving down the road, and just out of the blue my display saying trailer not connected, check trailer wiring.  What's worse is losing my breaks.  Have also dc'd my trailer and been driving and had the message pop up to check trailer wiring while there was NO trailer connected.  I don't think there was anything wrong with it, but I replaced 7 pin plug the plug on my trailer equipment trailer.  Have also had some issues with recognizing which trailer is connected, and sometimes will act up with the 4 pin plug on my stock trailer.  I am in the process of trying to rule out the trailering module, but I have read that some have had issue with it and had to have the module replaced.  If my problems continue, I will let the dealership replace the module while my truck is still under bumper to bumper.