RV Repair: electrical problem, turn signal switch, electrical problem

Question
I have a 1997 Shasta travel trailer that I'm having some problems with the electrical system? everything use to work fine whether it was plugged in a 220 vlt outlet or running off the 12 vlt battery, but lately the lights have been doing crazy stuff like some times they work and sometimes they don't some times the outside lights will stay on even after unplugging the tow vechicle and this last time we took it out we noticed our tail lights on the drivers side front and back stopped working, but the brake light does go on, we checked fuses and bulbs all are fine, can the travel trailers electrical system mess up the tow vechicle? and/or do you have any suggestions on how to fix it?

Answer
yes they can mess up the tow vehicle i just had a guy in the other day towing a brand new coach that was missed wired and burnt out his turn signal switch in his truck .
you will have to trace down the wiring on the trailer and find the problem either a couple of melted wires or a some corroded