I was wondering if someone could point me to a book, or some classes that would help me repair ECU's for BMW and Mercedes cars. I know a little about cars, but a lot about electronics. My friend owns a BMW and Mercedes mechanic shop and suggested that I start getting into re-building broken ECU's and re-selling them as refurbished units.

A book that describes this stuff would be great, and i see many books here, but not sure which one to get. I guess my first question is, does anyone know if there is a diagnostic tool which pin points which component/s have gone bad on an ECU board? I'm just starting to research into this stuff, so please excuse my ignorance on this subject.

Thanks for the help!