Tachometer doubling

[Cowboy Roy]

I have a 2011 SANTE 230 with a ZR409 and the mechanical tachometer is showing exactly double what the actual RPMs are.

The tach on the LINC appears to be accurate.

Any tips?

[Tom351]

I am not sure about the tach in this case, but I do know that many aftermarket automotive tachs have a switch on the back for 4/6/8 cylinder....Maybe this tach has that switch and is accidentally in the 4 cylinder mode?