Potential risks with disconnecting the battery

Mr. C4 · 01-26-2024, 06:40 AM

What are the potential risks with disconnecting the battery? Any precautions to be taken? I have read too many horror stories involving disconnection of the battery that have resulted in dead i-drive, fried FRM etc. I need to disconnect the battery on my M3 E90 to remove the airbag and steering wheel and it shouldn’t take more than 30 minutes. Any guidance is highly appreciated.

RocketyMan · 01-26-2024, 12:55 PM

Never heard of this before nor experienced it.

spammysammich · 01-26-2024, 02:10 PM

PO of my car is a BMW/Mini master mechanic and has told me he had one case of an FRM frying as he reconnected the battery to turn the car over to the customer. He claims he has heard of it happening a lot but only experienced it once.

RocketyMan · 01-26-2024, 06:19 PM

A quick search does reveal a potential service bulletin.

https://bimmerscan.com/wp-content/up.../B012016-1.pdf

bavarian06 · 09-11-2024, 07:34 PM

I had to remove the battery negative terminal to do a steering wheel swap. Sure enough, it damaged the FRM.

What is the appropriate way to remove the battery terminal? Wait for the car to go to sleep and then remove it? I have to send my FRM3 out for repair. Should I disconnect the battery before I remove the FRM?

Do modules get damaged when the factory seat is disconnected and swapped for a race bucket?

Mr. C4 · 09-28-2024, 12:11 AM

bavarian06 sorry to hear about your FRM going bad. Unfortunately I don’t have the answers to your questions. I ended up letting a garage do the work required with my steering wheel/airbag and hence I don’t know how they handled the battery/FRM.

Gesler · 09-21-2025, 10:35 PM

This just happened to me; changed the battery and it fried the FRM module (no turn signals or brake lights, couldn’t turn off headlights, no alarm or door lock or window function, ABS and DSC errors).

Searched online and found the warranty has been extended to 15 yrs / 186000 miles for this part. Was able to get it replaced at dealership under this.

RocketyMan · 09-26-2025, 01:42 PM

Quote:

Originally Posted by Gesler

This just happened to me; changed the battery and it fried the FRM module (no turn signals or brake lights, couldn’t turn off headlights, no alarm or door lock or window function, ABS and DSC errors).

Searched online and found the warranty has been extended to 15 yrs / 186000 miles for this part. Was able to get it replaced at dealership under this.

Thanks for posting your experience!

Here is the service bulletin since the original link I posted isn't working anymore. From my research, this is now the latest bulletin as of 2/23/2025.

https://static.nhtsa.gov/odi/tsbs/20...14417-0001.pdf

Seems like the pre-LCI cars aren't applicable, unless you have an e90..?

spammysammich · 09-26-2025, 02:42 PM

I believe it’s mostly FRM3 equipped cars.

01-26-2024, 06:40 AM	#1
Mr. C4 Second Lieutenant 270 Rep 233 Posts Drives: E90 M3, 328i Touring M Sport Join Date: Jun 2018 Location: Sweden iTrader: (0)	What are the potential risks with disconnecting the battery? Any precautions to be taken? I have read too many horror stories involving disconnection of the battery that have resulted in dead i-drive, fried FRM etc. I need to disconnect the battery on my M3 E90 to remove the airbag and steering wheel and it shouldn’t take more than 30 minutes. Any guidance is highly appreciated. __________________ 2010 E90 M3 2013 F31 328i Touring M Performance
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01-26-2024, 12:55 PM	#2
RocketyMan Captain 616 Rep 740 Posts Drives: E53 X5, E83 X3, E93 M3 Join Date: Nov 2022 Location: PNW iTrader: (0) Garage List 2008 BMW M3 E93 [10.00]	Never heard of this before nor experienced it. __________________ 2008 BMW M3 E93 MT R135 └┼┼┼ ..246
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01-26-2024, 02:10 PM	#3
spammysammich Lieutenant Colonel 2821 Rep 1,693 Posts Drives: 2009 E92 M3 Dakar Yellow II Join Date: Oct 2021 Location: Edmonds, WA iTrader: (0) Garage List 2009 BMW M3 [10.00]	PO of my car is a BMW/Mini master mechanic and has told me he had one case of an FRM frying as he reconnected the battery to turn the car over to the customer. He claims he has heard of it happening a lot but only experienced it once.
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01-26-2024, 06:19 PM	#4
RocketyMan Captain 616 Rep 740 Posts Drives: E53 X5, E83 X3, E93 M3 Join Date: Nov 2022 Location: PNW iTrader: (0) Garage List 2008 BMW M3 E93 [10.00]	A quick search does reveal a potential service bulletin. https://bimmerscan.com/wp-content/up.../B012016-1.pdf __________________ 2008 BMW M3 E93 MT R135 └┼┼┼ ..246
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09-11-2024, 07:34 PM	#5
bavarian06 Captain 115 Rep 949 Posts Drives: m3 Join Date: Apr 2006 Location: CA iTrader: (6)	I had to remove the battery negative terminal to do a steering wheel swap. Sure enough, it damaged the FRM. What is the appropriate way to remove the battery terminal? Wait for the car to go to sleep and then remove it? I have to send my FRM3 out for repair. Should I disconnect the battery before I remove the FRM? Do modules get damaged when the factory seat is disconnected and swapped for a race bucket?
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09-28-2024, 12:11 AM	#6
Mr. C4 Second Lieutenant 270 Rep 233 Posts Drives: E90 M3, 328i Touring M Sport Join Date: Jun 2018 Location: Sweden iTrader: (0)	bavarian06 sorry to hear about your FRM going bad. Unfortunately I don’t have the answers to your questions. I ended up letting a garage do the work required with my steering wheel/airbag and hence I don’t know how they handled the battery/FRM. __________________ 2010 E90 M3 2013 F31 328i Touring M Performance
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09-21-2025, 10:35 PM	#7
Gesler First Lieutenant 143 Rep 359 Posts Drives: e90 M3 Join Date: Jul 2007 Location: US iTrader: (0)	This just happened to me; changed the battery and it fried the FRM module (no turn signals or brake lights, couldn’t turn off headlights, no alarm or door lock or window function, ABS and DSC errors). Searched online and found the warranty has been extended to 15 yrs / 186000 miles for this part. Was able to get it replaced at dealership under this.
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09-26-2025, 02:42 PM	#9
spammysammich Lieutenant Colonel 2821 Rep 1,693 Posts Drives: 2009 E92 M3 Dakar Yellow II Join Date: Oct 2021 Location: Edmonds, WA iTrader: (0) Garage List 2009 BMW M3 [10.00]	I believe it’s mostly FRM3 equipped cars.
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