GM Trailer Brake Controller | eBay PRODIGY 90185 ELECTRIC TRAILER BRAKE CONTROLLER w/GM Adapter Plug-For 1-4 Axle. $74. Buy It Now. $50. 0 bids. Free Shipping. 51353 Curt Trailer Brake Control Adapter Wiring Harness fits GM 2003-2006. Trailer Brake Control Module ACDelco GM Original Equipment 20850925. $81. Buy It Now. SilveradoSierra • Electric Brake wiring harness Mar 13, 2010Electric Brake wiring harness? Mar 13 2010, 10:43pm ok even though my truck is used heard stories about the wiring harness for the electric brakes being hidden anyone hooked up for electric brakes so did u use the GM supplied harness or did u buy new?