I finally decided to pull a trigger on an alarm system for my E30. It was probably easier to install an aftermarket system but I really wanted a Genuine BMW remote on my key chain. I used a control unit out of a 96-99 BMW E36 3-series. You will need to obtain a control unit for the alarm system, wiring harness for the control unit, LED wiring harness, remote for the control unit and a siren. The wiring for the alarm system was spliced into the wiring for the lock control unit. One of the main issues with using E36 alarm system in E30 is the lock/unlock signal from the control unit. The way I understand it, E36 uses a ground signal for unlock request and +12V for lock request. E30 uses ground signal for both. To deal with this you will need to install a 4 prong relay. I used an orange Bosch relay used in E30 for a bunch of other things, see below on how to wire it. You basically are using a relay to covert a +12V signal into a ground signal. E36 pin numbers in the table below are for the wiring harness connector, not the control unit. Please note, wiring colors can vary. This project was done on a 91 318is. Verify wire functions with a multi meter and a wiring diagram for your year/model. Disclaimer: Information provided in this article may be incorrect and can cause damage to your vehicle. Use at your own risk!