Jumping tachometer

Does anyone have any idea where the Tach on a 96 Taurus with the Vulcan engine may get the tach signal? My tach has been at zero for a couple of years, so I switched it out and the replacement is also dead. You can take your finger and move the needle freely on both units, and when you start the car, it seems to be powered down....you can move it up and it moves down faster than with the key off.....any ideas? Just saw it come to life today for about a mile or so, then it died agian. Thanks...Dave:banghead:

The tach gets its signal from the Powertrain Control Module (PCM). The PCM gets its signal from the crankshaft position sensor.

-Rod