Trailer Tow Wiring

Vehicles equipped with an optional trailer tow preparation package are shipped from the factory with a trailer tow wiring harness and 4-pin trailer connector that is packaged with an instruction card and placed in the glove box of the vehicle. The trailer tow harness includes three relays designed to isolate the trailer park lamps as well as right and left turn signal and stop lamp lighting from the rear vehicle lighting and prevent overloading of the park, turn signal and stop lamp lighting drivers in the BCM. These vehicles also include a dedicated trailer tow park lamp control output circuit protected by a 15 ampere fuse located in the BCM.

If the trailer lighting is connected directly to the vehicle wiring without using the necessary relays, the vehicle electrical system will become overloaded and the rear lighting of the vehicle will cease to function. The BCM will store a Diagnostic Trouble Code (DTC) for this condition.