Our "check trailer wiring? message first appeared on the dic on January 5, 2016 on California highway 12, near fairfield, ca.0. we stopped and applied di-electric grease to the 7 pin plug. The message re-appeared and cleared itself, indicating trailer connected. At 7,380 miles, checked the truck and found no problems, and advised us of GM's trailer wiring tsb, and suggested the problem was with the trailer and that we purchase a specific pollak 7 pin trailer end plug. They provided the name of a nearby truck shop, who that the specified pollak plug. We headed overnight to chowchilla, ca and the next morning, replaced the 7 pin connector with the pollak plug, and we cleaned and checked the trailer ground at the king pin. We left chowchilla and in urban traffic, the check trailer wiring message would appear as we applied the truck brake and then clear itself with trailer connected as we headed down the highway or freeway. We went through urban traffic in palmdale and lancaster, ca that same day, and at a stop light on level ground, with the "check trailer wiring message appearing, I applied the manual trailer brakes, and took my foot off the truck brakes, and the trailer/truck rolled ahead - no brakes on the trailer. We experience occasional message on the dash indicating 'check trailer wiring'. we are towing a fifth wheel trailer weighing over 13,000 lbs. We took the truck to a GM dealer and were told of a tsb regarding braking issues, and were told to replace the 7 pin plug with a 'pollak' brand. We had an rv dealer check our trailer brakes, and said they work fine. We have spoken to another GM dealer who indicated that the new integrated brake controllers are advanced and will detect any issues with our brakes, and give the check trailer wiring message. The message is intermittent and eventually clears itself......updated 02/10/16 updated 11/2/2017 updated 06/20/18

- Williams Lake, 00, USA