I measured voltage from battery neg. to ecu both earths (picture). I was getting 1,18V at Key off and 7,3V at key MAR. That's not good. Other earths show 0,02V which is good.
Perhaps spliting this thread and renaming the new thread would be appropriate, after my posts around 8, 9 and 10 the thread has very little to do with the original post about a "Rude Fiat dealer".
Yes Title of this thread it's way off but it's only thread with similar problems to my. Which I found solution today! Happy times.
Those two grounds were my pain in the... with the voltage showing at 1.3V so I bypased them with a cable directly to battery negative with great success.
Now it runs for short while then it dies. But that's for another thread.
Actually its probabely best you keep it going in this thread because post 10 onwards are related to your problem so when Davren splits the thread from the original Rude dealer posts it will make good reading for other members with similar ECU faults ..