2012 GMC Sierra Hopkins Custom Tail Light Wiring Kit for 2012 GMC Sierra tow bar wiring from Hopkins. Product reviews from other Sierra owners. Expert tow bar wiring advice with thousands of helpful questions and answers. Guaranteed lowest price and fastest shipping. Hopkins Custom Tail Light Wiring Kit Installation - 2007 GMC Sierra New Body.4.6/5(17)Category: Tow Bar WiringBrand: Hopkins 2012 GMC Sierra Vehicle Tow Bar Wiring | etrailer Call 800-298-8924 to get Expert Service ordering a Vehicle Tow Bar Wiring for your 2012 GMC Sierra. Complete installation instructions and lifetime technical support on all Vehicle Tow Bar Wiring purchases. Lowest price guarantee on accessories for your GMC Sierra and the fastest shipping available.