I would look at the OVP. It sounds like you are dead in the road. You can verify it by looking at the EHA current.

The EHA current is what matters so it is the bottom line on control. I forget what car you are working on but there is no version I know of that goes 0% at KOEO (key on engine off). Late cars require the term 3 to be initiated in diagnostic mode via an impulse request at the right side diagnostic socket. These cars do read key KOEO properly though.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician