2016 f650 6.7 here with flatbed on it.

With headlight switch in the off position, when you use the left blinker everything works perfect. 2 blinkers in front, rear blinker, and blinker in light bar.

When you hit the right blinker, all lights on the truck flash. Right side, left side, front and back, light bar lights, lights down side of the bed on both sides of truck. The only spot i see a difference is the actually front right blinker bulbs flash dim. Everything else is flashing away like crazy on this thing.

While its happening, turn on the headlight switch and everything stays solid like it should, turn it off and all flash again.

Swapped in from another of the same truck headlight switch, multi function switch and BCM. Still same problem.

Driving me crazy over here. Even looked inside battery junction block for shorts or corrosion and see nothing.

Any ideas? Anyone ever seen this before? Trying to find the connection between the factory lighting and flatbed light and not coming up with anything.

 

A 2016 should still be under warranty, unless you've made aftermarket lighting changes?

If you have, go back to the last thing you did, it sounds like you have a hot wire touching another wire.

 

thanks Mike, Yes i figured it was something like that just cant seem to locate it. Cant find the common connections between the two. It may be inside battery junction box, but on here the box is all hardwired to the harness so not messing with that just yet. I haven't done any lighting work since this truck was delivered to me. After ford built it was sent to jerrdan to install the flatbed and hydraulics, light bar and some other small lights but that was when the truck was new over 11 months ago. No Problems until now on this one.

Not sure if ford will give me a hard time since they didnt put that stuff on. Was trying to avoid taking a truck off the road as were all ready running thin and use these trucks alo.

 

We had a problem after a flatbed was put on a F350 a few years ago and it turned out to be a poor ground on the loom the upfitter installed. A little grinding off the paint took care of it.

 

Well you said the blinker on the right?? was really dim?, try unplugging the blinker and see what happens? It could be shorting out there.

 

Yes did try that still have some issue. Also just disconnected power going to all rear lights on this truck. Rear brake, turn, light bar, bed lights everything. None of those lights are working. With that off and disconnected is still have same problem in the front of the truck, which does lead me to believe it is something on the ford side.

Have been working on this on and off for the last two days, would really like to figure this one out and not have to send it in.

 

You might look at the Ford Fleet Truck body builder layout book. It might help you solve the problem. This contains information that is for builders who might add a body to a chassis cab or other configs.

https://www.fleet.ford.com/truckbbas...6/maintoc.html

I just noticed the electrical link isn't working. The 2015 should be the same...

https://www.fleet.ford.com/truckbbas...bodybuild.html