FYI - The OVP is an electrical "surge protector" which protects sensitive electronic devices on the car from a voltage surge - which could damage them. On my 420 car, the following are powered by the OVP...

CIS-E
ABS
Idle Speed Control Unit

You should get some sort of voltage at pins 1 and 2 of the round X11 diagnostic connector if the CIS-E has power.

There would also be some sort of voltage at the Idle Air Valve if that was getting power.

If the ABS is not getting power, the ABS light would be on with the engine running.

As for the EHA, that is not a "plug-and-play" device! Rather it is "analog" and quite mechanical - not "digital"! Somewhat like a Swiss watch mechanism which requires delicate adjustments so it works just right. Might want to read about it here...

(Following for a RR, but same Jetronic EHA theory of operation - See page 9)
http://rroc.org.au/wiki/images/c/cd/B_Bosch_KE2_Jetronic_Injection_Part_2.pdf