GMC/CHEVROLET: CHECK TRAILER WIRING MESSAGE IN DIC POOR CONNECTIONS AT 7-WAY). THIS CONCERN COULD BE CAUSED BY A POOR CONNECTION AT THE 7-WAY TRAILER CONNECTOR. THERE ARE SEVERAL MANUFACTURERS OF 7-WAY (TRAILER SIDE) CONNECTORS AND NO INDUSTRY STANDARD SPECIFICATIONS FOR THESE CONNECTORS. MODELS AVALANCHE, SUBURBAN, TAHOE, SIERRA, SILVERADO, SIERRA DENALI, YUKON, YUKON XL. *PE