Running Lights on 2 Trailers Not Working with a 2005 Dodge Ram 1500

Question:

We picked up our new outback 5th wheel and pulled it home with our 2005 dodge ram 1500. The truck has a factory tow package with the 7 pin wiring plug in the bumper. we were about to take off on a camping trip on a cloudy day when I turned the lights on. I looked back in my mirrors to see the running lights were on and then go dim, then out. I thought I had burnt out a fuse so I checked the fuse box. NO BAD FUSE??? I then checked my turn and brake lights on the trailer and they work fine. OK,we are not going to tow at night so I can still go camping. The camp ground we are staying at has a big lake we like to fish so after we got set up camping I drove home to get our boat, GUESS WHAT, same problem, brake lights work, turn lights work, but no running lights. When I got back to the camp ground I decided to take the factory plug trailer connector apart on the truck to clean all the pins on the plug, still no running lights. HELP , I`m running out of ideas

asked by: Denny G

Helpful Expert Reply:

When you checked the fuse on the truck did you check the truck's running light fuse or the tow package running light fuse? They are independent of each other on most vehicles. There also could be relays associated with the tow package wiring that you can check.

A good start was to clean the trailer connector but if there is no power on the running light circuit then the issue is further forward somewhere on the truck. And if it is not a fuse or relay then it is likely a damaged wire somewhere between the front of the truck and the trailer connector.

You can trace the running light wire forward as far as you can on the truck and if you find any areas where the wire is damaged then fix as needed.

Another possibility is that both trailers have a lot of running lights that when combined draw more power than the tow package wiring can handle. If there is power at the connector without a trailer connected then this scenario is more likely. If the lights start working after you disconnect a few of the ones operated on the running light circuit then over draw is the likely issue and I recommend switching to LED lights.

If you just cannot determine the issue on the truck then the easiest fix is to run a wire from one of the truck's tail light running light wires to the 7-Way and bypass the vehicle tow package wire. You could put a 10 amp fuse in line with that wire to avoid drawing too much power from the tail lights.

expert reply by: Michael H