I actually worked on my car yesterday - trying to diag the keyless entry.
I had one diamond key that worked up until a year or so ago. The second key never worked for keyless entry since we bought the car in 2016. Tried reinitializing both keys, but neither would would do anything.
Instead of replacing the batteries next, I remembered I had found a broken wire in my trunk harness for the third brake light a couple of years ago, so yesterday I traced the wire for the FZV antenna amplifier (which is what detects the 315MHz keyless entry signal) to check that it was powered. I had a hunch that that wire was broken as well, but it turns out it has 12 volts and the fuse was not blown. So I ordered a new/used FZV module off ebay, and will try that before replacing the batteries in my keys.

(It is powered by fuse 86 in the trunk, by the way - not fuse 49 like it says on BMWGM5.com)


Somebody posted where you can buy brand new diamond keys for $150 or something like that - I am at the point where I will spend or do almost anything to get it working again.

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2003 3.0 5MT Topasblau
Purchased in 2016 and sold in 2024
2012 35d Platingrau