Chased down an electrical issue, thought this may help someone else later
So I started experiencing a blown brake light switch fuse situation on our 2016 (2015 really, was actually built Dec 2014 we found out) E450 Super Duty after installing an electric brake controller a couple of weeks ago. The main issue with this is, no brake lights mean no shifting out of Park...thankfully the brake controller activates the brake lights thereby letting me shift out of Park to get home.
I chased everything I could think of under the impression that I caused this issue somehow with the brake controller. Even resorted to uninstalling the controller...but it would still blow the #30 fuse under the hood...intermittently.
We spent most of the day Saturday, starting at the 7 pin plug in the back and working our way forward, finding nothing out of the ordinary. We finally noticed at one point the brake lights were on while the pedal was not being pushed...so I headed to the dealer to get a new brake light switch. While my friend was installing the new switch, I just happened to walk behind the RV and noticed the brake lights were on, so I yelled...he yelled back "there isn't even a switch installed right now" and started to crawl back out off the floor and the lights went off, I yelled again "lights off" then they were on...then off...then on...then off...then the fuse blew again.
What we found was by pushing down on the plastic footwell between the drivers seat and door, we were shorting a wire out that was backfeeding the brake light circuit somehow. There are about 7 large harnesses that run in that area, some factory Ford and some coach related. One wire had another wire crimped onto it and the plastic may have had a bit of the metal crimp inside it just poking through the plastic...we think this was the culprit. We wrapped it real good with tape and then put some plastic wire loom over the whole harness and ever since I have not blown the fuse again.
I was even able to plug the electric brake controller back into the harness and pulled the trailer around a bit successfully with no issues. I'm crossing my fingers it's fixed for good.
It sucked having to do this on a basically new RV, but things happen. I could have taken it in to either an RV or Ford dealer as it's under warranty but my friend that was helping me is an ASE Master Ford Mechanic and even he was stumped as to what was causing it. It was dumb luck that we found it and a single tech working by himself might have never found it. Plus, I need the RV for a trip out of town next weekend.
Anyway, I now know more about the wire harness on my E-450 than I ever wanted to know, including the fact that the high center rear light is not a brake light which was a surprise to me. Hopefully this can help someone else down the road.
2016 Coachmen Concord 300DS