Why does a 2001 dodge ram have 8 wires running to the trailer plug when only 7 are needed?

The extra wire in a 2001 Dodge Ram's 7-way trailer connector (despite only needing 7 for standard functions) is typically a ground wire. While the frame of the truck itself *can* act as a ground, having a dedicated ground wire improves the reliability and prevents electrical issues caused by corrosion or poor ground connection at the trailer's connection point. This dedicated ground path ensures a cleaner signal for the lights and other electrical systems of the trailer.