One advantage of this option is you may have more choice of vendors and therefore an opportunity to get a lower price. The 5AS in the Rover Mini is mounted vertically such that there is an upper screw and a lower screw. Then they used their insider connections to reach people who worked for Rover. Note, if your 5AS doesn’t respond to your fob, the fix may be simple (don’t assume that programming is needed): Make sure the fob battery is not weak or dead. They contacted Don and got a new ECU. They installed the new ECU, but of course the car would not start because the new ECU was not “mated” with the old immobilizer system. BMW tried everything to get the car to start.
Most common “fobs” (the plastic remote for your keychain) are the 2-button 3TXB, 3TXC, and 3TXA fobs by Lucas. You usually have to remove your radio to get at it. Update 2012/04/19: I have just learned from the folks at remobilise.co.uk that there is now a way to marry together the ECU with *any* 5AS. This is great news because now it means you can repair your car even if your original 5AS dies.
Please contact me if you have more information or corrections! If you own a Rover Mini, please join the Rover Mini Owners Group on Facebook Most, if not all, of the Rover Minis of this era are equipped with the Lucas 5AS alarm / immobilizer system. The diagnostics socket is typically located under the dash and near the steering column. Option 2: You can remove the 5AS unit inside your dash and mail it to folks in the UK who will program your 5AS to accept one or more fobs.