I don't now about the Siemens ECU but a reflashed Marelli will work fine with no dash or immobiliser connected.
hello Derek, nice to have you here again, OK. thanks, my ECU is Marinelli. in this forum in a link here, I found a lot of info and almost similar problems described. https://www.ducati.ms/threads/how-t...20-in-order-to-remove-the-immobilizer.734571/ the fellow who started, from Cambodia, has not replied to my call for contacts, asked him for files and a description for the procedure and aftermath of the new dash (some chip Chinese, on, as he said).. It seems that is not a complicated procedure, but still, it takes a time to do it alone, and a mistake could be just around the corner... Professional tuners asking more than 300€ for that.
