'89 200 tq - disappearing coolant & after run control unit

[Bruce Bell]

I just replaced a failed and leaking Aux. pump. No visible signs of
leaking coolant now, yet a cup or two disappears after each drive. The
new aux. pump still isn't running and I have tracked it to a weak ground
(pin 1) which goes to the after run control unit. Are these control
units a failure mode? Or, should I look to the ground welded in the
right engine harness? I did get an intermittent buzz/click from the
driver's side foot well.

Are these related? Where is the coolant going?

Bruce