Changed battery in key fob(non-CA) doesn't work

cjet68 · 01-23-2022, 12:37 PM

I opened up the key fob(non-comfort access) and soldered in a new battery. The car won't unlock or start. How do I reprogram the key?
Is there a way to make the car recognize the key?

The other key still works but I don't want to change the battery in it until I get this one working.

e90yyc · 01-23-2022, 03:35 PM

I have some questions:

What was the battery voltage after install?
What happens if you insert it into the key slot and then hold down the Start-Stop button for ~15 seconds?
Prior to the battery replacement, did the key work to start the car when put into the slot, but just not to lock/unlock with the remote? If different, describe pls.
What battery did you solder in?
Any chance you damaged the PCB in the process of opening the key up?
Why are you considering changing the battery in the other key? Is it completely dead? If not, leave it alone.

All that said, I don’t think this is a key programming issue. To my knowledge there are no further steps required when replacing the VL2020 in these keys, other than of course being very careful not to damage anything when opening the housing.

01-23-2022, 12:37 PM	#1
cjet68 Enlisted Member 3 Rep 45 Posts Drives: 2019 M4CS, 2005 M3 Join Date: May 2011 Location: connecticut iTrader: (0)	Changed battery in key fob(non-CA) doesn't work I opened up the key fob(non-comfort access) and soldered in a new battery. The car won't unlock or start. How do I reprogram the key? Is there a way to make the car recognize the key? The other key still works but I don't want to change the battery in it until I get this one working.
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01-23-2022, 03:35 PM	#2
e90yyc Art Collector 2640 Rep 3,620 Posts Drives: 2007 328xi (GM-delete 6MT) Join Date: Feb 2018 Location: Canada iTrader: (0)	I have some questions: What was the battery voltage after install? What happens if you insert it into the key slot and then hold down the Start-Stop button for ~15 seconds? Prior to the battery replacement, did the key work to start the car when put into the slot, but just not to lock/unlock with the remote? If different, describe pls. What battery did you solder in? Any chance you damaged the PCB in the process of opening the key up? Why are you considering changing the battery in the other key? Is it completely dead? If not, leave it alone. All that said, I don’t think this is a key programming issue. To my knowledge there are no further steps required when replacing the VL2020 in these keys, other than of course being very careful not to damage anything when opening the housing. __________________ When I'm dead, just throw me in the trash.
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