I have a 1997 V90. It must have been one of the very first ones to have the V90 badge instead of the 960.

My mechanic says he's about 95% certain that there's a problem in the ECM (the idle motor, which is supposed to run for about 15-20 seconds after the ignition is switched off, keeps going until the ECM is disconnected). We've been trying to locate a used ECM, partly to swap (to confirm the diagnosis) and partly because it's cheaper than new. (I haven't actually asked the dealer; anyone know what the new price is?)

However, the part number appears to be pretty rare. I haven't located any on the Internet (there was one listed in an expired eBay listing, but it was sold). It's not included in various lists I've seen in searching the 'net, and even a big ECM rebuilder like Programma says they won't work on it because they don't have its details.

My mechanic is very reluctant to swap in an ECM from a 1997 960/V90 with a different part number. Does anyone have any info, or know where I could find some, concerning the interchangeability of ECMs from similar vintage cars but with different Bosch part numbers?

FWIW, the part no. on my ECM is 0 261 204 239.