BCM or FRM module issue?

2005 BMW Z4
145,000 MILES • 2.5L • 6 CYL • 2WD • AUTOMATIC
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BHAMDOC1
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I am aware the GM5 or FRM modules are common to go out, at least on BMWs. I bought this one as is. Starts and drives fine. Convertible top does not worried to either find or replace the BCM. Blinkers do not work. Windows do not work. I see someone has tried to either check where the BCM is or replaced it with a used one , am not sure but I saw the module hanging like this. Based on symptoms do you suspect the BCM or FRM? The locks work I tried them. Oh and the battery is dead, must be jumped to start
Apr 11, 2026 at 3:51 PM
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STRAILER
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I would start with a new battery because it can draw the voltage of the system down if it is no good. Then run the codes by doing a CAN scan so we can se what is going on with the system.

CAN SCAN - https://youtu.be/u-4syLc-ifQ

Run the codes and let me know what you find.
Apr 12, 2026 at 9:35 AM
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BHAMDOC1
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Will dox thanks
Apr 12, 2026 at 10:35 AM
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STRAILER
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Np, let me know the codes you find.
Apr 13, 2026 at 8:46 AM
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BHAMDOC1
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I stalled a new battery a d of course there were ton of codes due to low voltage. These were the codes before i deleted everything. I will post the codes if any after deleting all so you can see what is still there.
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Apr 14, 2026 at 8:49 AM
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BHAMDOC1
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Failed to communicate with:
-Central information display
-Top module
-Light switching center
-Instrument cluster had 2 codes i cleared them and they deleted, a BE and a k bus
-radio
-airbag module
-SZM
-ZKE central body electronics
Apr 14, 2026 at 8:57 AM
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BHAMDOC1
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Only thing am worry about is why this gm5 module has a date of 1-5-26 and is dangling, so it must have been changed with a userd one and they thought it will fix the issue. Now i have no way to know whether this is the original one or not and whether they coded it i can ot communicate with many modules so either gm5 or the bcm or frm
Apr 14, 2026 at 9:02 AM
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BHAMDOC1
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These popped back under instrument cluster
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Apr 14, 2026 at 9:03 AM
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BHAMDOC1
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Couple of people had similar issues and they said they teplatthe airbag module behind the hand brake u der the console and it fixed it. They said when they disconnected the module everything worked. Can you tell me where it is and how to take it off
Apr 14, 2026 at 9:26 AM
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BHAMDOC1
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Removed the connectors to the airbag module and everything worked but the top. Not sure if it needs reset
Apr 14, 2026 at 10:31 AM
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BHAMDOC1
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The panel that controls the top has 5 buttons all work except the top neither open or close light up. Cannot communicate with that module. Can you see where the fuses are? No sound at all from top
Apr 14, 2026 at 10:48 AM
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BHAMDOC1
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Not sure if these matter, they popped up
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Apr 14, 2026 at 10:51 AM
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STRAILER
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The image is too small to read, can you enlarge it or tell me the codes?? So you unplugged the airbag module and it fixed everything except the top? I say you found the problem and the top is a separate issue.
Apr 15, 2026 at 7:32 AM
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BHAMDOC1
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attached
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Apr 15, 2026 at 7:45 AM
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STRAILER
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Hmm I don't think this has to do with the top, this looks more like the window operation issue, does both windows work?
Apr 15, 2026 at 7:46 AM
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BHAMDOC1
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both windows work up and down, but because it is a convertible whenever you press the top to latch remember they have to go down a bit, also when you close the door they should roll up a bit, but they are doing neither nor
Apr 15, 2026 at 7:48 AM
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STRAILER
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Yep, that is not right, this will be the general module issue which is what they were trying to replace, I would start with the reprogram of the module or try a hard reboot of the system this video can help.

https://www.youtube.com/watch?v=INiDRO5A5MY

Please let us know what happens.


Apr 16, 2026 at 8:48 AM