Tachometer wiring?

[Crazy4408pac]

My wife bought me an Autometer 5" tac w/shift light, as a surprise. I have a question regarding the blue wire (see below marked with red arrow).
Do I need to hook this up? I have no idea what it's for, as I have no switch hooked up to my shifter.
Thanks

 

[grassy]

your diagram is too small for me to see..

I have the 5 inch with shift light but mine looks different..

The 4 wires you need are :

1 -Power
2 -ground
3 -line to coil
4 - background light..

 

[Drag]

I due believe that the blue wire is optional
on autometer instruction there a note on the 3rd page
(NOTE: If you prefer to use only one shift point, do not connect the Blue wire as shown in the diagram in
the Wiring section and only set the High Shift Point)

 

[Crazy4408pac]

Thanks.