Tach Reading Low..

[markboss]

Tach reads correct at idle around 900..
At 1500 rpm tach reads 1200
at 3000 rpm reads 2000
Scanmaster used for reference.
Anybody have any idea on repair?

 

[kidsixpack]

I've never heard that with these (modern cars) but like the old ones maybe the tach is wearing out. Hopefully someone here will have some insight.
KID

 

[TTA984]

Tach reads correct at idle around 900..
At 1500 rpm tach reads 1200
at 3000 rpm reads 2000
Scanmaster used for reference.
Anybody have any idea on repair?

Did some testing today with tach & scanmaster. My readings were very close to the same, + or - .25 on all readings.