Weird light issue, any ideas??

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oskywawa

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So this happened once a few weeks ago and it went away after turning on the ignition and off again, but it’s back tonight…. Basically after my truck is off the lights under the side view mirrors, the white lights over the back window, and the little white light on the tailgate randomly light up, “tick” up in intensity, shut off, then do it again over and over. No real pattern to the timing and can’t seem to get it to stop. No idea what to even try to fix it.

Here’s a video of the issue of it helps….

 
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FordTechOne

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Anything aftermarket? Another poster on here had the same or similar issue, it was caused by an aftermarket HUD plugged into the diagnostic port.
 
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oskywawa

oskywawa

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Yea I have aftermarket fogs I installed a few years back that connect to the overhead switches but I haven’t had any issues like this until now. I do have a hud/tac connected to the diagnostic port as well (also for a few years), but even when I unplug it this continues. I’m thinking I may just be due for a new battery, I still have the original battery in it and I’ve had the truck for 6 years or so. Figure either way it’s probably about due for a new one even if it doesn’t solve the issue. Next guess may be an alternator issue?
 
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oskywawa

oskywawa

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ordered an OEM battery today (BAGM-94RH7-800) and will see if that solves the problem. Will report back for anyone else who may have this issue in the future.
 

FordTechOne

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Yea I have aftermarket fogs I installed a few years back that connect to the overhead switches but I haven’t had any issues like this until now. I do have a hud/tac connected to the diagnostic port as well (also for a few years), but even when I unplug it this continues. I’m thinking I may just be due for a new battery, I still have the original battery in it and I’ve had the truck for 6 years or so. Figure either way it’s probably about due for a new one even if it doesn’t solve the issue. Next guess may be an alternator issue?
The alternator isn’t operating when the truck is off. Unplugging the aftermarket HUD is not conclusive, as there may still be DTCs set. I’d recommend checking/clearing DTCs with ForScan and re-evaluate.
 

smurfslayer

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THIS.

I overloaded the cargo light circuit trying to get +12v to my rear facing squadron lights. It didn’t blow a fuse, but did set a (?) BMC code IIRC. Cleared with FORSCAN and back in business ( routed that +12 properly for use with a relay after that) .

2nd poster we’ve had with the HUD / OBD port having weird lighting issues on the Jen Too.
 
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oskywawa

oskywawa

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Well i disconnected my battery overnight and re-connected it this morning so I could check for DTCs. Didn't find anything and now everything seems totally normal. I still picked up the new battery and will probably put it in anyway since it can't hurt to have a new battery and the old one is 6 or so years old. I appreciate the input here @smurfslayer and @FordTechOne !
 
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oskywawa

oskywawa

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Wanted to chime back in on this one…. Replaced the batter to solve the issue about a year ago, noticed recently it started happening again. Ended up replacing the switch in the truck bed and that fixed it for good! Hope it helps someone else who may run into this.
 
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