hi
forgive the crude drawing. this was a test circuit i was given for a 3 wire hall effect sensor. the description says the voltage reading on the volt meter should vary from 0 to 6 volt as the sensor switches on and off. i tried the circuit but it doesnt work. is the intention that the meter is an easier route for the voltage than the 1 k resistor and the resistor is there to complete the circuit to allow the sensor to function.
the signal wire switches to ground when the sensor is on if i just remove the resistor and have the meter in its place.

 

I think there is an error. Where is the other end of the sensor connected? Right now, the meter is only reading the supply voltage. Your meter should (usually) be reading from sensor to ground (left side of resistor to ground).

 

the sensor feeds a speedometer and this is the method given to test the sensor out of circuit on the bench. it just didnt seem logical to me i thought i must be missing something. as i say without the resistor and just running through the meter is appears that the sensor wire runs to earth when in the on mode which is how i thought it should be. i was expecting a positive output on the sensor wire but i guess it can be either way round dependent on circuit design inside the speedo.