General Trouble Shooting
This guide is not meant to be a full training manual on all aspects of RV wiring, rather it is designed to help the average do-it-yourselfer find and repair the most common wiring problems. If you are not comfortable using tools or if the problem is found to be in the wiring harness of the tow vehicle, it is recommended that you seek the help of a professional.
Most problems with RV wiring originates in the tow vehicle socket and/or the trailer plug. With all the rain water, road salt, and grime thrown up by the tires, these components are subjected to the worst conditions for an electrical connection.
First, check the inside connections of the tow vehicle socket for corrosion, broken wires or other obvious problems.
Then inspect the trailer plug for the same conditions. Any deterioration of the terminals or the wires themselves should be repaired now. It is often more economical (and less stressful) to replace the entire plug/socket and make any needed repairs to the wires at this point. Often the problem is solved before delving deeper into the wiring maze.
If all looks well, then continue with the trouble shooting guide.