9200i dashboard disco

[PeteMelb]

Hi all, I have an interesting problem I'm hoping someone can assist with. We have an Iveco 9200i that for the last few runs the dash goes crazy, all gauges point to the floor the engine warning lamps all start to flash the warning beeping starts the speedo and taco also point to the floor.

HISTORY: For the past few months we have been trying to resolve an ABS error on this truck that keeps showing up intermittently its always the same error L/H rear sensor fault. I've replaced the sensor without success Ive checked all wiring and found nothing, I even weakened and took it to a auto elec and he told me to change the L/H sensor again, which I reluctantly did and still no joy. So I put the truck on single trailer work until I could resolve the ABS issue.

Then a few days ago the dash went psycho, the truck still runs perfect its just the dash thats stuffed, I did some reading and found the ABS unit could possibly cause this so I removed the ABS relay and the dash was fine replaced the relay the dash went crazy, so finding this and having another 9200i available I swapped the ABS ecu units over thinking I've got it sorted but NO still does exactly the same thing so its not the ABS unit and I'm out of ideas.

Any Ideas would be appreciated.