Comfort Access Door Handles Leading to Battery Drain/Car Staying Awake - Need Help

Long story short I've had an ongoing electrical gremlin/parasitic drain I've been trying to track down for the last year+. I've replaced batteries twice, replaced the alternator, EDC control module, and repaired my faulty footwell module to no avail. I discussed with a dealer friend who suggested the comfort access door handles are a common fault that leads to battery drain and the car staying 'awake'. The staying awake issue is a clear one as my gear indicator, start/stop button, and iDrive controls sporadically illuminate well after the car has been locked. I decided to start pulling fuses related to the doors and see if this solved the sleep problem. Luckily it seems to have done just that. Now the car will go asleep and stay asleep within around 30 minutes. A huge relief as I'm at least on the trail. I've narrowed it down to fuses 79 and 61 on the diagram. Both of which are related to the door locks.

My question pertains to the next steps here. It seems there is an actuator in the door related to the locks that typically fails and can be replaced. Is that what I should be targeting? I should mention that comfort access is working fine on both doors as far as physical functionality is concerned (locking and unlocking). Should I open up the door and see if there is a crimped wire first or something of the like? Is there a way for me to determine which door to start with rather than wasting time taking apart and troubleshooting a door that may be fully functional? (50/50 shot)
I'm in attack mode and just need to know where to aim so any help would be appreciated.

Edit: This didn't work. Still hunting..

Old post: Scratch that. I don't know how to delete a thread but it seems like you can remove the door handles from the exterior rather easily. I'm going to do that and unplug the comfort access and see if that solves the problem then I can decide if I want to replace the handle(s) or just live without comfort access.

I can’t remember but is it possible the trunk comfort access is on the same circuit?

I’ve just replaced two CA door handles because mine had failed.

Easy to take out the handles, but the YouTube videos on how to put them back in are actually wrong, they often mention using a pick tool to make sure you are engaged with the spring by pulling it forwards.

Actually all you need to do is reinsert the handle so that the lock mechanism is engaged - you will feel it by test opening - but the handle doesn’t sit back all the way into the door. At this point, all you need to do is insert the lock barrel or the corresponding blanking piece if it’s the passenger door, and the handle will click into the correct place when you do, then just tighten the Torx bolt back up.

I remember reading a while back- that the comfort access door handles can fail and prevent the car from going to sleep.

Supposedly when this happens, the handle will remain warm when the car is off. You can verify this with an IR temp gun. Compare the temperature of the handles from the rest of the car, and to the other handles in the car. If one of them is bad- you just need to replace the handle.

Sad news, it was not the door handles.. I disconnected both and it still refused to go to sleep. Was really hoping it was something that simple.

I will say that there is a solenoid click that comes from the rear view mirrors that seems to start the 'awake' cycle followed by the Start/Stop ignition button illumination, the 'P' indicator on the dash, and finally the DCT knob lights all illuminating. About 30 seconds later they all turn off one by one, the mirrors click, and it all starts again.

Have you tried disconnecting the trunk antenna?

Adam M wrote

Have you tried disconnecting the trunk antenna?

I have not. Willing to try anything at this point, I'll look into it. Any pointers?

I seem to recall (though I'm getting old now) the IBS can cause a parasitic drain, as well as cause the battery not to charge properly, if it goes bad, or isn't securely connected. I made a post about the IBS in this thread:
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https://www.m3post.com/forums/showpost.php?p=28628664&postcount=6
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https://www.m3post.com/forums/showthread.php?t=1852097

I appreciate you sharing this. Will look in to IBS I recall reading about this in my past diagnoses but left it unchecked for whatever reason.

Space Fox wrote

I appreciate you sharing this. Will look in to IBS I recall reading about this in my past diagnoses but left it unchecked for whatever reason.

Did you ever fix your problem? I'm have a similar problem. Battery is draining after about 2 days of sitting. Fairly new battery, and my symptoms are No CA only on driver side. passenger and trunk work fine. I'm getting (4B6C engine ventilation heater, control) New code only since the car died (wouldn't start and flashed dash lights the common low battery stuff) a few weeks ago. I've read about the handle staying awake and ibs. But what was the fix?
Thanks,

lci335d wrote

Did you ever fix your problem? I'm have a similar problem. Battery is draining after about 2 days of sitting. Fairly new battery, and my symptoms are No CA only on driver side. passenger and trunk work fine. I'm getting (4B6C engine ventilation heater, control) New code only since the car died (wouldn't start and flashed dash lights the common low battery stuff) a few weeks ago. I've read about the handle staying awake and ibs. But what was the fix?
Thanks,

I disconnected both handles and no dice, they weren't hot to the touch either. I'm at a bit of a loss, currently I am just disconnecting the negative terminal when the car is going to sit for more than a few days. It only takes 10 seconds so not the worst solution but still a total cop out and admission of defeat.. I think I've got a crimped wire somewhere or something of the sort. I replaced the alternator, foot well module, EDC module, checked the alarm module, comfort access, and even started pulling fuses - all of the common sources I could find. Definitely a head scratcher.
Is yours 'waking up' when it's sitting?

Space Fox wrote

I disconnected both handles and no dice, they weren't hot to the touch either. I'm at a bit of a loss, currently I am just disconnecting the negative terminal when the car is going to sit for more than a few days. It only takes 10 seconds so not the worst solution but still a total cop out and admission of defeat.. I think I've got a crimped wire somewhere or something of the sort. I replaced the alternator, food well module, EDC module, checked the alarm module, comfort access, and even started pulling fuses - all of the common sources I could find. Definitely a head scratcher.
Is yours 'waking up' when it's sitting?

I'm honestly not sure. How could I check? I am noticing. I've only had it loosing bat this bad for about a month. I just hooked it to a battery charger and it got up to 93% state of charge. Drove it 2 days and it's at 76%. Still getting the engine heater code.

Space Fox wrote

I disconnected both handles and no dice, they weren't hot to the touch either. I'm at a bit of a loss, currently I am just disconnecting the negative terminal when the car is going to sit for more than a few days. It only takes 10 seconds so not the worst solution but still a total cop out and admission of defeat.. I think I've got a crimped wire somewhere or something of the sort. I replaced the alternator, food well module, EDC module, checked the alarm module, comfort access, and even started pulling fuses - all of the common sources I could find. Definitely a head scratcher.
Is yours 'waking up' when it's sitting?

One last thing to think about: How far away is the Key-fob when the car is parked. IF the Key-fob is closer than 15 feet (approximately) the comfort access can engage and keep the car 'awake'. Store the Key-fob far away from the car. Also replace the Key-fob battery and only use the BMW Roundel button in the center of the Key-fob to lock it.

Do you have something plugged into the usb port in the armrest?

Go through the fuse panel with a meter and see what's pulling power.

I’m wondering IF the battery was ever properly registered and coded to the DME correctly for CCA and ampere hours to tell the alternator how much power to charge it correctly??

lci335d wrote

I'm honestly not sure. How could I check? I am noticing. I've only had it loosing bat this bad for about a month. I just hooked it to a battery charger and it got up to 93% state of charge. Drove it 2 days and it's at 76%. Still getting the engine heater code.

Yours could be the alternator if it's draining while driving. A quick trip to Autozone and they can test the alternator.
Mine only drains while sitting. With mine I can see through the window that the shift knob lights up, the P lights on the dash, and the ignition button ligths as the car cycles awake like every 10 minutes or so while sitting.

DrFerry wrote

One last thing to think about: How far away is the Key-fob when the car is parked. IF the Key-fob is closer than 15 feet (approximately) the comfort access can engage and keep the car 'awake'. Store the Key-fob far away from the car. Also replace the Key-fob battery and only use the BMW Roundel button in the center of the Key-fob to lock it.

I've stored the key fob across the house in a closet but no luck.
Yes I've registered each battery that I've installed with Carly (which I heard recently doesn't actually register the battery correctly?) Either way that is more an alternator charging issue than a parasitic drain while the car is stationary/turned off issue.

jellydoughnutt wrote

Do you have something plugged into the usb port in the armrest?

Go through the fuse panel with a meter and see what's pulling power.

This is a good idea - How would you do this? Voltage meter with the car off and unplug one fuse at a time and test that fuse port?

Nothing in USB port

Space Fox wrote

Sad news, it was not the door handles.. I disconnected both and it still refused to go to sleep. Was really hoping it was something that simple. I will say that there is a solenoid click that comes from the rear view mirrors that seems to start the 'awake' cycle followed by the Start/Stop ignition button illumination, the 'P' indicator on the dash, and finally the DCT knob lights all illuminating. About 30 seconds later they all turn off one by one, the mirrors click, and it all starts again.

This post caught my attention from back in 2024. Have you tried pulling the fuse for the rear view mirrors you mentioned? The thread below shows images for the fuse box diagram. https://www.m3post.com/forums/showthread.php?t=321638
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According the A-Eye: "For a BMW E92 M3's auto-dimming rearview mirror, the main power fuse is often Fuse 21 (7.5A) in the glovebox fuse panel, powering both the mirror and outside mirrors; however, functions like Homelink (if equipped) might draw from the roof module, potentially involving fuses like F62, F25, or F7, so check the specific fuse diagram in your glovebox, as locations can slightly vary."

Space Fox wrote

This is a good idea - How would you do this? Voltage meter with the car off and unplug one fuse at a time and test that fuse port? Nothing in USB port

See the YT video linked below about how to test the fuses with a multi-meter (without removing them) to check for parasitic drains.
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DrFerry wrote

See the YT video linked below about how to test the fuses with a multi-meter (without removing them) to check for parasitic drains.
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This is great stuff man thank you. I'm going to pull that mirror fuse and see if it solves the wake up issue. If it does not I'll buy a voltage meter and see if any of the fuses are drawing power while the car is off and go from there.

I didn't see where they checked for parasitic draw. I think the only way to do that is to interrupt the circuit and put the meter inline and check amps/current draw.

@Space Fox did you resolve your issue, I have a friend down on Sarasota going through something similar and looking for ideas.