BMW Z3 keyless entry and switched USB power using only the OEM alarm harness.

(I said 10 volts for some reason in here.. 12 volts!) For what it's worth, I used this product from Amazon. I thought the 2 button remote looked period correct. https://www.amazon.com/dp/B09BNMBCDH I only used the OEM alarm connector that's behind the glove box.