Everything seems to work right including the dash tell-tale light, but nothing happens when I push the starter button for reverse. Only change is; the light flashes steadily while the starter button is held down. I know precisely when it failed, it made a half hearted effort for 1/2 second (engine only reved up a little) and nothing since. I have a service manual and have figured out there are some conections to check, but I'm wondering if it is likely to be the control unit? and is there a positive computer diagnosis that could be done by a REAL BMW mechanic? I'm in no hurry, I can live without it.