SOLVED: BM53 Issues

[sbay]

Hey everyone,

My M3 keeps blowing BM53s (or so I think), on my second replacement now. The radio goes completely dead for a bit (5-10 mins), I get a message saying BMW Assist Inactive and then it decides to finally start working. After the second BM53 replacement, all worked fine, then the same issue happened within 2 days. Audio quality is completely muffled as well. It used to be clear at high volumes and muffled at low, now it’s completely muffled. Any ideas?

Car is a 2004 with OEM Nav/DVD/CD player/HK audio.

Thank you.

[Casa de Mesa]

What is a BM53? Is that the radio? Having grown up with a nurse in the family, this is how I read your first sentence:

"My M3 keeps blowing Bowel Movements 53..."

[DropTopKingM3]

BM53 is a radio tuner which is located in the trunk on Nav based cars.


sbay your best bet is to browse this forum. There's tons of information pertaining to C43, BM53/ BM54, MKIII, MKIV, etc.


Navigation System - Xoutpost.com

[WestBankM4]

The BM53 failed on my car, except the symptom was when turned on, it emitted a high frequency squeal of sorts.

Did some research and instead of buying a new one, I shipped mine to a guy who repairs the processors and the unit itself. I ended up upgrading it with different processors so the sound quality is a lot better than factory.

I'm just rocking an OEM Nav unit with BlueBus at this time with the upgraded BM53 and it's great so far. Probably do a BavAuto upgrade in the near future.

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[WestBankM4]

Here's his card.

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[sbay]

Thanks everyone. Will report back if a solution is found!

[t3ddftw]

Hey everyone,

My M3 keeps blowing BM53s (or so I think), on my second replacement now. The radio goes completely dead for a bit (5-10 mins), I get a message saying BMW Assist Inactive and then it decides to finally start working. After the second BM53 replacement, all worked fine, then the same issue happened within 2 days. Audio quality is completely muffled as well. It used to be clear at high volumes and muffled at low, now it’s completely muffled. Any ideas?

Car is a 2004 with OEM Nav/DVD/CD player/HK audio.

Thank you.

The BMW assist message sounds like you have replaced the rear view mirror with a non-assist mirror. To resolve this issue, remove the TCU, which is the silver rectangular box located at the top of the electronics stack where the Amplifier and BM53 live.

As for the issue with the BM53 itself, are you sure your amplifier isn't the culprit? There's no good reason for two BM53s to be ruined in such close succession, which leads me to believe your amp may have been on the way out.

-Ted

[sbay]

t3ddftw Ah, yes I do have a replaced rear view mirror. Thank you for the tip, will remove the TCU.

As far as the amplifier, I did try a replacement after the second BM53 change, however that did not solve the issue. Will try one more BM53 change and see if that helps. Will report back. Thanks, Ted!

[sbay]

Solved…another replacement BM53, no issues since. Bad luck with the first two I guess.