The vehicle has a Trailer Sway Control (TSC) feature as part of the StabiliTrak system. If TSC detects that the trailer is swaying, the vehicle's brakes are automatically applied.

When TSC is applying the brakes, the TCS/StabiliTrak indicator light flashes to notify the driver to reduce speed. If the trailer continues to sway, StabiliTrak will reduce engine torque to help slow the vehicle.
TSC will not function if StabiliTrak is turned off. See Traction Control/ Electronic Stability Control.
Towing Equipment
Conversions and Add-Ons#13-00-89-004C: Car and Truck Fix it Right the First Time Issues - (Oct 10, 2013)
Subject:Car and Truck Fix it Right the First Time IssuesModels: 2014 and Prior GM Cars and Trucks This bulletin has been revised to include updated information. Please discard CorporateBulletin Number 13-00-89-004B.In order to access this bulletin electronically, go to the SI Home Page and selec ...