To measure current flow you must use an ammeter between the wiring connector & the EHA.. MB makes a special adaptor..but if you use a jumper wire from 1 female pin of the connector back to the corresponding male pin of the EHA & then connect the ammeter wires between the other female back to the other male pin you can watch current flow.
Should be 75ma with key on & engine not running. When starting that will change & can go as high as 200ma while cranking. will(should) slowly drop to a cycling positive/negative flow as the engine warms up.

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