Check trailer brakes

[Buster#1]

The check trailer wiring warning flashed on and off intermittently as the trailer breakers fail and then return.  The connector seems good and trailer brakes seem good...GM dealer said connector checked out etc..  

[Wynn1427]

Disc brakes on trailer? Dont know what your trailer mfr is, but there is a decent thread (https://www.mygrandrv.com/forum/showthread.php/29517-2021-Sollitude-factory-disc-brakes-not-working-with-2020-Silverado-3500HD) with similar issue and possibly resolved by added an to the system actuator.