There should be two connections.

EHA 1 ---------------Connector going to CIS-E engine computer.
EHA 2 ----Meter-----Connector going to CIS-E engine computer.

Does not matter which wire the meter is in series with, you would be able to see "amperage" changing. Also the car needs to be warmed up to 80C. (running temperature) for the system to be in (closed loop) and so you will see the meter changing.

The CIS-E gets its power from the Overvoltage Protection Relay (sort of like a surge protector).