How to test for faulty coil drivers on an MSD80 type of BMW engine ECU. Set your meter to diode check, touch the negative lead to the backplate of the driver (or centre stub leg if you like) and touch the positive lead to each main leg. You should see voltage drops of around 0.5v on one leg and around 1.3v on the other. Anything in that ballpark is OK. Bad drivers will often show as shorted on one of both legs. The replacement part is an IRF644SPBF in DPAC form which are fairly common from RS Components, Digikey and many others.
