All right, this is an odd one. I’m trying to debug my battery dying overnight, and while I can’t seem to be able to trace any draw, I came to the car this morning and the headlights were on. Car was locked, tail lights off, switch in the “auto” position.

I am 100% certain when I parked the car last night the lights were off (it’s something I would have noticed with my current issues, lol).

I can’t even seem to find any threads about something like this - headlights randomly turning on. What should I look into? Or is this a straight to the dealer problem?

 

Battery low or a footwell module issue is my guess?

 

Footwell module could be it, but why would battery low be a cause of headlights turning on?

 

low power creates all kinds of bugs in the system

 

Interesting. Fair enough. So you’re saying the headlights are possibly a symptom and not a cause for the battery drain. Rats … back to hunting for it then. Is the JB4 known to sap power when engine is off?

[edit] wait. lights just came on now (what sort of weird timing is that …), and car is sitting on a trickle charger! so definitely not low charge!

 

Yep, sound like a footwell module or something.

 

Check your car for codes — if you have BimmerLink, include info codes as well — as noted if the car gets weird, it’s gonna get weird. The stack of codes can help those of us who have seen it before get a bead on what might be going on — maybe. If you can get them, post em up.

While chasing wacky power issues in my F56S I had my headlights decide to come on — or stay on, never did get clear, but same net result — just like you. And at the center of root cause was a parasitic draw.

 

Hmm. Interesting. So you’re suggesting it’s not necessarily a defective FRM module? In your case, what was the power draw?

I’m going to hook up Esys and try to get it working. I did have a JB4 hooked up, but it wasn’t doing a great job reading codes. Anyway I decided to start pulling anything non-OEM so I removed it to see if I can track down the power draw.

[Edit] btw, how did you diagnose the power draw? I have a separate thread on this without too much traffic but I haven’t been able to diagnose it with a clamp meter so I’m trying to figure out how to hook up a multimeter “correctly” - do I just undo the ground and hook it up, or do I set it up in parallel and move the circuit over, etc. - any advice there welcome.

 

Easy part first.

The end of my problem is detailed in this post -- and I figured out what it was by following another forum member's "last touched first suspected" guidance. It was the only accessory added to the car after I bought the car used, and I added it personally by following manufacturer instructions (that manufacturer being BMW/MINI -- which is why I never suspected it in the first place). Bottom line is the install instructions created a short circuit/parasitic draw that screwed up, in no particular order:

- battery (drain, ultimately had to replace)
- auto stop/start (due to battery condition)
- alternator ability to keep charging the battery even while running
- power steering (intermittent loss at engine start along with chassis stabilization warnings and related weirds, and I'm not the only one, apparently)
- a variety of other weird things that it became clear were comm failures between various modules, caused by low power to said modules, with the low power caused by the short/parasitic draw.

More complicated stuff:

Since you have an F56 (I picked that up from your other thread), we've either got or mostly got the same car (mine is a 2017 S). That means you don't have a footwell module, or at least not one named as such. The footwell module aka FRM is in the R series; in the F56 you have a BDC, aka Body Domain Controller. Most of the things that the FRM handled are in the BDC now, and the BDC is in fact mounted on the outside of the RF footwell. In my case, the drain was impacting *several* control modules, including the BDC.

I got very close to either replacing or rebuilding my alternator over the whole thing, and the SoH (State of Health) of my battery got worn down to the point where I had to replace the battery. At one point it was suggested my power steering rack might need replacement, all the more credible because on certain F-Series BMWs that is a real thing with a recall attached. Net, parasitic draws are not fun on this car; aside from making you batty, they can have you replacing high-dollar parts that actually aren't broken. What @ECSTuning said is 100% correct: "low power creates all kinds of bugs in the system." Loud emphasis on "all kinds."

Since the last thing I added to the car was the actual problem, and I knew the most about it, and it was easy to electrically disconnect, identifying it as cause meant:

- check codes (knowing I had one persistent one, see my longer writeup at the thread.
- electrically disconnect accessory.
- clear codes.
- run car and see what codes and/or problems returned.

Main problem code (complaining of short circuit) and all other major symptoms vanished. After 17 days running this way, no further issues, I declared the problem solved.

The thing to remember about the MINI (or a BMW of similar vintage) is that it is basically a small computer room that happens to have wheels and an engine. I think my old R56 had at least 6 computers (control modules) in it. I have no idea how many are in the F56 other than that there are more. Computers do NOT like insufficient power -- and when they have insufficient power (example: at engine start, and then beyond as the battery is drained), they do weird things (not simple things like just switching off altogether). Wire 6 or 8 or 10 computers together that are supposed to be a harmoniously-communicating orchestra and make them all unhappy at once... it can get weird really, really fast. But if you straighten out the power, all the things that seem catastrophic might just clear up.

 

Ohh hoho, I did read that thread - apologies, I didn’t click it was YOURS. Yep. The F56 is definitely more complicated than my R56, and diagnosing something so odd as a power draw is not fun. The most irritating thing is that a clamp meter is showing nothing - so I don’t know if it’s an intermittent draw or what. I also don’t know where to start: the only thing I added since I got the car is a radar detector, but it’s wired off the same hot wire as the other (previously added) aftermarket stuff (TV gateway etc), so it can’t be the cause since that’d mean it’s the _other_ stuff’s fault. But it’s also indisputable that the battery is running down, so I dunno.

Hopefully a scan will help a bit, pretty much the only benefit of having 65 computers in the thing …

 

Yeah, with all the additional accessories getting +12V from a common wire, it could be any or none of them, or for that matter, the combination of them (finally went over some threshold). I'd be curious to know what that common +12V wire is spliced/otherwise attached to (meaning I want to know what the supply wire/source is on a wiring diagram).

Just to make things more complex, one of the accessories could have developed an internal short. In the case of my Click & Drive, I didn't have to have anything plugged into it for the parasitic draw to occur. All it needed was the bad-idea-BMW wiring plan and the supplied-with-kit USB-A accessory charger. Electrically the whole thing is nothing but:

- +12V accessory socket (wired to car as per kit instructions) -- no electrical connection between +12V and GND unless you plug something into the socket.
- kit-supplied BMW USB-A charger (plugged into kit-supplied accessory socket)
- USB-A male to female extension cable, with male end plugged into kit-supplied charger, and female end idle in the Click & Drive unit until you plug something into it.

With nothing plugged into the female end of the extension cable embedded in the Click & Drive unit, I still had the short/parasitic draw, so I unplugged the kit-supplied charger, and the short/parasitic draw went away.

Even though you couldn't pay me to wire the thing is as the instructions said ever again, I have distinct suspicions that at some point the accessory charger behavior malfunctioned, thus creating the short. Can't prove it, but I suspect it, even though the wiring directive was asking for trouble on its own.