Thread: MDM retrofit
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      11-20-2025, 04:44 PM   #7
VicS5
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Drives: 2009 E92 M3
Join Date: Feb 2018
Location: Albany, NY

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No, not yet. One of buddy’s kids stopped by over the weekend to help. He’s an EE, so he at least has a better grasp of electronics than me - a monkey with a multimeter.
We pulled the cover off the stock button cluster and he confirmed that the button circuit has nothing more than a resistor in it. We tested voltage changes observed with presses of different buttons and found they vary by only a couple of millivolts, so the SZL is probably very sensitive to resistors with loose tolerances. I still can’t understand why it works sometimes and not others. Seems to me if I’ve got a bad resistor in there, it wouldn’t work at all.
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