Hello, I'm new to this forum and could really use some help! I have a 1990 740 Turbo, that would start when cold, but would not re-start when warm. After running every concievable check that I was able to do myself, and no success, I turned the car over to a shop with a pretty good reputation with Volvos. After re-checking everything I did and then some, he determined the ecu had failed as it was not sending injector pulses. I purchased a re-built unit which he installed, but the car would not start at all. I sent both the original ecu, and the rebuilt unit back to the company for testing and the tech there replied that the Hybrid fuel control board had failed in both units!
He replaced the board, checked it out OK, and returned the unit with a note to check for any possible shorts that could damage the ecu, even while only cranking the engine. My mechanic said he re-tested all components and could not detect any apparent shorts, although he said checking every wire would be considerably time consuming. When he installed the newly rebuilt ecu it would still not start the car. Has anyone had any experience with shorts or components damaging ecu's? Is there something else I should be looking for? Any help would be greatly appreciated! ol'jer