Install the charge line by running a length of 8-gauge, automotive stranded copper wire from the engine to the rear bumper. The wire should be run so that it is protected from sharp edges, the exhaust system and points of abrasion. Enclose the wire in a flexible conduit and attach it to the truck using black UV protected tie wraps or zip ties. This line powers the truck's RV receptacle.
Mount a 50-amp circuit breaker to the fender well or engine firewall. Connect the lead wire from the wire you just installed to one side of the circuit breaker. Connect the other end of the circuit breaker to the battery terminal located on the alternator using another piece of 8-gauge wire.
Locate the wiring harness near the truck's taillights. Use a multimeter or 12-volt test light to probe each wire as the brakes, turn signals, flashers and reverse lights are operated. The test light will indicate when an electrical current is present. Connect the truck's lights to the RV trailer wiring kit. The wiring kit allows you to disconnect the wire's multi-pin connectors and attach them to adapters located on the wiring harness without cutting the original wires. Match taillight to taillight, left turn signal to left turn signal, right turn signal to right turn signal and reverse lights to reverse lights.
Attach a 1/4-inch bolt and ring terminal to a clean portion of the truck's chassis. It should be close to the trailer plug receptacle. Run the white 8-gauge automotive wire from the charge line to the bolt as a ground.
Attach the 7-pin or 9-pin trailer plug receptacle to the charge line and the wiring kit. It is standard practice within the RV industry to locate the trailer plug receptacle to the left of the trailer hitch. Most trailers will have a 7-pin plug. RVs with Dometic refrigerators may have a 9-pin plug. Install the correct receptacle for your trailer.
