Random exterior lights on

[oldskewel]

Very weird light situation. Fixed but not understood. Posting this to see if someone has any clues or similar experiences.

Summary: crazy random exterior lights came on while parked. Controls + fuses had no effect. Instantly back to normal after momentarily disconnecting battery. Wondering what might be wrong.

2001 3.0i, 206k miles
Hardly gets driven, waiting in my driveway for me to have time to do engine work on it.
Charged the battery a couple of days ago, after finding it very low (reason unknown, not normal - could be related, I think). Charging went well, battery appears good, starts up with no problems. I thought it was good after that. Then ...

Today I noticed RANDOM exterior lights on: left fog light, right brake light, both taillights, right front parking light

My wife texted me a photo, and I did not get a chance to look into it until I got home 3 hours later, still in same state when I got there.

Car was still locked. Unlocked it with remote fob, no problem. Confirmed turn signal stalk was in off position. Headlight switch in off position. All light controls as they should be. Battery voltage (seen on power outlet gauge) about 12.0V.

Hooked up battery charger. It started taking a charge just fine. Charging overnight now.

Figured I'd pull fuses and then get to solving this when I have time.
Glovebox fusebox, fuse #9, 5A, brake lights. Pulled it and right brake light was still on. Key in, turned to ON, and all 3 brake lights on (with brake pedal not pressed, and fuse #9 pulled). Stepping on brake pedal does not change anything.

With key turned to ON, headlight switch still off, lowbeam headlights came on.

"Light Module", fuse #2 and 9 (9 was already pulled), 5A. Pulled it and nothing changed.

Checked fuse box in cargo bay, nothing related to lights.

====

So I went back to the battery and disconnected the negative terminal for a few seconds. Then reconnected it and the car is back to normal.

Any ideas? Is my car possessed? LCM on its way out? Weird voltage glitch due to recent low battery, not likely to repeat itself?

[EODguy]

I have no idea, but I sure as hell won't read this anywhere NEAR the White Witch or she'll do it too...

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[Effduration]

These cars do strange things during and after low voltage situations...They also don't seem to like to sit.

You might check to see if you have a parasitic drain...if you do, the resulting low voltage situation could be causing it and/or whatever is causing the parasitic drain could be your problem.

[X5chemist]

Sounds like a circuit is back feeding power to others. I would do a voltage drop across fuses. A connector somewhere probably has corrosion. Start at the LCM connector. Water intrusion would cause corrosion there.

[workingonit]

Originally Posted by oldskewel

Very weird light situation. Fixed but not understood. Posting this to see if someone has any clues or similar experiences. ....

It's a German vehicle, so it has a Poltergeist, naturally. I had one that appeared in my garage, soon after I got my '66 Chevelle (not German, but I have the DNA). It remained with me for 27 years, in my garage, sometimes causing mystery problems, sometimes helping me find others (on whatever vehicle I was working on in the other two bays of the garage).

It seems to have moved on when I traded the Chevelle for my X5, in '21, so now I only have those pesky Gremlins bothering me, as I work on my vehicles outside (mostly). Or is it just me? hahaha

[oldskewel]

Thanks and LOL for the comments so far. I'm not really hopeful to get an answer here, just some ideas to keep an eye out for or maybe dig into to check something.

So I'll find the LCM module at some point and give it a visual. At least knowing where it is and how to get to it will surely be useful.

I know how hard (impossible) debugging intermittent problems can be when they are not present. Hoping this is a one-time only event, but hope ain't ...

I don't think I have a parasitic drain. About 8 months ago, I was having an intermittent one, which was mysterious until I noticed the HVAC blower would sometimes be on with the key out. Clear symptom of the FSR, so I pulled 50A fuse F64 from the glovebox fuse box and have had no voltage problems since. I actually think I may have been having that FSR problem for a couple of years, but only found it when it got bad enough. But I'll keep an even closer eye on voltage.

I know I need to get the engine work done and get this thing back in service. Right now, it is taking up a spot in the driveway until I can find time to do it (with sufficient priority). As an example of things higher up on the list, I need to do 5x tax returns for myself and family members in the next few days. After that, my son's Alfa is parked next to it in the driveway with its own major engine issue, and I need to get that rolling first. At least the BMW can be driven onto the street and around the block to make space to work on my other cars or open a lane for the garage queen to get out. One day ...