"Service trailer brake system" on 2016 GMC
Have a 2016 GMC 3500, 6.0 gas job with 57K miles. Constantly now my computer screen beeps "Service Trailer Brake System", even when no trailer is hooked to truck.. took to my local trailer guy, he ...
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I would take apart the connectors behind the bumper and make sure none have moisture in them. Assuming there isn't a failure with the brake controller, it's seeing a connection to the brake actuating wire at the trailer connector. That could be moisture, rodent damage, etc.
