It is my best guess that you don't have your meter set up properly. Most meters don't read amps and volts with the wires plugged to the same holes.

As far as current goes polarity matters for point of view but not quantity. You should get 20ma with the key on and engine off. Also, to measure current the meter must be in series with the circuit. Voltage readings are read parallel to the circuit. This means that to read EHA current you must remove the two pin connection. The ammeter will then be connected from one terminal of the harness to one terminal of the EHA. The other terminal then must be jumpered from the EHA to the other harness pin. In this configuration current flows through one leg of the harness through the instrument, through the EHA, through the jumper into the orginal harness and back to the controller.

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