I'm curious, when dealing with ecm sensors in general, there is a 5.0 volt source going to the sensors, there is a signal voltage going back to the computer depending on the sensor (I.E. on-off or variable resistance) RIGHT ??. if so, shouldn't the source voltage remain at 5.0 volts +/- regardless of the state of the sensor ???. now, the reason I'm asking is:

I have a variable temp. coolant sensor, when the wiring harness is unplugged from the sensor I get 4.96 volts on the source wire and 0.00 volts on the signal wire to the comp., this sounds right to me.

if I plug the harness back into the sensor I get .75 volts on the source wire and .75 volts on the signal wire, this sounds wrong to me.

if I unplug the harness again and place a jumper from the source wire to the signal wire, the source drops from 4.96 to .75 and the signal goes from 0.00 to .75 when the jumper is installed.

NOW, is it just me or is something wrong here. the car has been acting up lately and I think I have traced it to this sensor. is it natural for the source voltage to drop like this or is there a problem with the computer ???