Not to belabor the point, but what ECU do you have. The number and label color.

I am not doubting your abilities by asking this, it is just that in the last few days we have seen more than one post where poor fuse contacts were the cause of a lot of troubleshooting effort despite the fact that "the fuses were checked". So it would be to easy to eliminate the ECU as the cause if you have a 951 or a white label 561.

I see you jumpered the fuses that are supposed to give a definitive diagnosis. While you were in the fuse box, how did those fuses look.

Here is the definitive check (for me) of the ECU grounding issue that plagues the pink/purple label ECU's:

http://www.brickboard.com/RWD/volvo/1471840/220/240/260/280/quick_check_ecu.html

When I do not do the equivalent of ticking off every box in a systematic troubleshooting checklist, even those that cannot possibly be the issue, I always miss the easiest and cheapest cause for any issue. YMMV.

Like the alternator ground wire, the collapsing intake hose (7-series turbos), the flaky fuses/fuse clips and the 25 amp fuse holder, I have gotten bit by the bad pink-label, too.

Mike