Ignition electrical fault

It could be MDI failure, it has been a common fault on the Volvo D1-30 and D2-40 engines. There are various symptoms, we have had 3 replacements now, the last one also included a new start button panel. Our main problem was a signal being sent to the stop solenoid, so we had to disconnect the solenoid connector to prevent the engine cutting out. But also suffered the start button not working, so had to cross the live from the MDI to the starter relay to start the engine. A real pain in the arse, Volvo think they have it sorted now, time will tell, I think it prudent to have a back up in place for those awkward moments