123 Diesel Tach Issues
 

Can anyone tell me what the clearance is between the pin on the crank pully and the TDC sensor should be? I just installed a brand new TDC sensor (mine was missing) and I was under the impression that if I were to put a meter on the 2 pins on the TDC sensor's electrical connector I should see a fluctuation in resistance every time the pin on the crank pully disrupts the field. I am not seeing any such fluctuation and wonder if my TDC sensor is not close enough to the pin to get a good reading. Also, what is the pin made out of?

Thanks in advance.

I presume the pin is a magnet but it may only be iron.

I don't think the resistance of the sensor changes. There will be an induced AC voltage that should appear across the terminals when the engine turns.