Sunpro monster tach

[zappa]

Help needed fitted tach today but cant get it to work,getting power to it cause shift light works,took the live from the battery to an auxiliary fuse box live from tach into that ,earthed onto body and green onto negative on coil got nothing tried everything I know still nothing also there are two buttons on the tach it says hold bottom in and turn top one to set shift light still nothing happens any ideas cause I'm stumped.

 

[john the horse]

Change it to four cylinders on the back?

 

[zappa]

It's set at 4 cylinder still nothing as I said getting power to it as shift light lights up could be a dude ,bought it of a guy on fleabay was sealed and unopened will. Persevere with it cheers for reply cheers rob