Suggest you check the continuity from the coolant sensor to the connectors at the ECU. With your meter hooked, up, jiggle the wiring and see if the readings change.

You can check the wiring harness by slitting the vinyl jacket or taping in various places (especially where it's likely to get hot) and looking for crumbling insulation on the wires.

You might have a bad EHA and the ECU is saying "Under these conditions I shouldn't have to be sending this much current to the EHA to control the mixture."

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe