This one has me stumped and I am hoping someone on here can help solve. My 2011 F250 has no front or rear running lights working, mirror side marker lights not working and fog lights not working. I have checked all fuses including 30amp trailer light fuse and they are good. The fuses in the passenger kick panel are not getting energized. I replaced the switch with a friends from same truck and no luck there. The headlights, dash lights and turn signals work fine. Here's the kicker, when I back feed 12V to the yellow/blue wire at front running light it turns them all on, including mirror lights. I've switched out relays in the box under hood and that didn't help.
When I pull the switch on dash to turn on the fog lights the indicator in the switch doesn't work either, they are both listed on the same fuse but as I said, the fuses have continuity across the blades but when I test the socket there is no voltage going to them. I have not connected a trailer to see if those are out yet but will do today. Any Suggestions?

 

Well, I hate to say this, but this ain't an older generation lighting system. It's way more complex in how it operates.

The headlamp switch (and other column switches) serves to signal a module under the steering wheel called the Steering Column Control Module (SCCM) what you want done (turn on parking, head or fogs or whatever). The SCCM then creates a computer message that is sent via one of the vehicle's networks (HS-CAN)to the Body Control Module (BCM) for actual execution.

In the case of the parking (running) lamps, the BCM energizes an internal (non-swappable) relay that energizes fuses F30 and F40 in the BCM. F30 operates all the exterior parking lamps except the mirrors and roof lamps (if installed) which are on F40.

Since back-feeding power activated both circuits, The problem is upsteam of those two fuses. That leaves the BCM and the SCCM as your suspects. Based on the detailed information you provided(), I followed the diagnostic procedure and it concluded the BCM was to be replaced. I wouldn't exclude the SCCm as a suspect though without further data which may not be available except to advanced Ford-specific diagnostics.

 

I do miss the days when I could diagnose just about any problem with a test light and a 1 inch wooden dowel rod. Thank you very much for your timely response, I actually had the problem solved later that day. I spoke to a neighbor of mine down the street that used to work on cars and read to him what you would said and he told me disconnect your battery and then reconnect it. I thought he was messing with me but I did it and it fix the problem, lights have been working fine all week. He said I basically reset that module that you were describing which I don't see how that could fix it but whatever it works. Thank you again.

 

Though I prefer to do most maintenance, when it comes to electrical gremlins I tend to go to the dealer. Had a couple separate issues with a past truck, thanks to the mice loving to chew on the soy based wire covering used. Ford found and corrected the issues very quickly.

 

Since back-feeding power activated both circuits, The problem is upsteam of those two fuses. That leaves the BCM and the SCCM as your suspects. Based on the detailed information you provided(), I followed the diagnostic procedure and it concluded the BCM was to be replaced. .[/QUOTE]

Hijack alert-separate question as you seem learned on the electrical. I am running a fused line from the battery to a switch panel in the back of the pickup bed to run various lights in the bed and exterior. I am adding some rock climbing lights directly into the reverse lights circuit for added light when backing up. I am also looking at tying the added backup lights into the switched exterior lights I am adding. These would only be used when the truck is parked but possible running. The main purpose of the added exterior lights is for unhooking the camper when we arrive at a campground when it's dark. Would backfeeding the reverse light circuit cause any concern? 2016 CCSB 4x4 Lariat 6.2. Thanks. Sorry for the hijack

 

Sorry, don't have technical data for the 2016.