Tach not working right

[dirtnap]

my tach always reads between 1 and 4k rpm, even before I start the engine, any clue as to what's causing this?

thanks

 

[boggs1227]

sounds like a electrical mechanical fault. i think that maybe the tach head it's self has gone bad ( i'm thinking that the movement is a air core design and the calibration is way off on the dial to what it should be ) .

.....of course it always pays to check all fuses and electrical connection before replaceing a questionable bad part .