Passenger Headlight Stuck On ALWAYS - 2013 SCREW

[Martin Arnold]

So, 2013 SCREW - problem is the passenger side low beam HID headlight is stuck on all the time..... doesnt matter what position the switch is on in the cab, nor if the key is in the ignition, it will stay on unless I pull the fuse, or disconnect the battery.

I took the truck in for a transmission flush and oil change at the ford dealership, pretty sure it was fine after that, I then sprayed it down in a car wash bay. later went out to go the store notice the passenger low beam was on....

Now, full disclosure, I replaced the headlights and tail lights on the truck about 2 months ago.... everything has been fine up until the other day when this happened. I plugged in the driver side headlight into the passenger side harness and it stayed on, so that rules out the bulb, ballasts, and wiring from the housing. After leaving the truck with the fuse out, and battery disconnected for 24 hours, I put it all back, and the headlight was off...... I went for a drive and about 20 min later, the headlight was stuck on again.

Has anyone got any ideas/thoughts/things to try?

TIA

 

[Martin Arnold]

So after a few days of leaving the fuse out, I popped it back in, and everything seemed normal. Came home last night, parked the truck, all the lights went out. I went back into my garage a few hours later and the DRIVER side lamp was fast blinking erratically....... =/

Do we think maybe its a bad BCM? Ive not seen any other symptoms/issues

 

[BenBB]

That's really getting weird, I have no idea but would be interested to hear what you find. May very well be BCM; you already eliminated bulb/ballast/wiring, and if it was the switch itself or the sunlight detector they would both be on at once; I have noticed mine will keep the factory HID's lit when you park for a few seconds after locking and exiting (again, both lights not just one side or the other) and I assume it's the BCM that controls that. You said you replaced taillights and headlights, just bulbs or assemblies?

 

[Martin Arnold]

Assemblies. I had to reuse the HIDs fro the OEM headlights and put them in the new housing.
But yeah, really odd, sucky part is, its still under warranty, but I presume I'd have to put all the original taillights and headlights back on otherwise they will blame them

 

[BenBB]

Well then it's kinda good news/bad news. PITA to swap them out but you could get warranty coverage...but if you do all that and put 'em back on and it happens again you're back to square one, and probably wouldn't get another one free. Sucks that it's intermittent but seems to happen fairly soon after shutdown. I think I'd try swapping just the headlights back out and see what she does, then taillights and if it still does it take it in; might be some kind of voltage/resistance in one or the other that the BCM doesn't like, could be totally unrelated and just a BCM failure (at the very least in that case taking it in on warranty can diagnose it as such). Good luck!

 

[Martin Arnold]

Thanks! I appreciate the ideas, and yeah I think thats the route I will have to take. I'll post back up here with results

 

[Martin Arnold]

So, is this an accurate diagram of the wiring? If so, am I right in saying regardless of what the BCM does, both left/right (passenger/driver) side lights would operate together.... which would rule out the BCM?

 

[BenBB]

That's what it looks like; that the BCM isn't involved...unless it's at the junction box fuse/relay(?). But what else would control the "Auto" function of the Main Light Switch? I don't see that, or the sunlight sensor, or what determines that it's time to light 'em up at dark thirty...I'm not an expert by any means though...

 

[Martin Arnold]

yeah I dunno... I agree the BCM has to be involved.... but everything I can tell would be that anything up to the fusebox would basically operate both in parallel.

 

[BenBB]

That's what it looks like, I'm wondering if that's the high beam schematic(?). One other thing you could try, is next time one stays on trace the wires with a test light or voltmeter; not easy to trace the full length but maybe start at the headlight to identify which color wire is hot, then check it at the BCM connector, then where the harness splits between sides...