BCM or FRM module issue?

Tiny
BHAMDOC1
  • MEMBER
  • 2005 BMW Z4
  • 2.5L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 145,000 MILES
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
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Saturday, April 11th, 2026 AT 3:51 PM

2 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 55,404 POSTS
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.
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Sunday, April 12th, 2026 AT 9:35 AM
Tiny
BHAMDOC1
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  • 224 POSTS
Will dox thanks
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Sunday, April 12th, 2026 AT 10:35 AM

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