I just purchased a used 3h slant with living quarters. Everything worked when I checked it out but it was hooked up to their truck. When I hook it up to mine (04 Dodge 2500) everything works( running, brake, and turn lights, and brakes) but the interior lights and backup light. I'm using the same type adapter as they were using. My truck has a 7way plug and the trailer a 6way. I'm using a 7 to 6 way adapter. It's got to be something stupid. I've checked all my fuses. I did have a bed plug put in with my goose neck hitch. Could they have wired something wrong? I still have the original plug on my bumper but that does the same thing. It looks like they just tapped into that plug for the bed plug anyway. Any ideas?
Posted 2008-05-17 10:07 AM (#84120 - in reply to #84104) Subject: RE: interior light problem, please help!
Expert
Posts: 5870
Location: western PA
Not sure about Dodge trucks, but my Ford diesel has to be running to get power to the aux lighting circuit. However that would have nothing to do with your back up lights which is a different circuit. If all the lights worked while being attached to the other truck, then your wiring must differ.
Retento has posted some excellent wiring diagrams for trailer and truck plugs. Purchase a new seven pin plug that matches your truck. Install it and throw away your adapter. There are different adapters and some work while others don't. For under $10 you can eliminate your problems.