Thanks gents its back to the store with it I think the tech line said I could try a zener diode with a rating of 10 or more?
![Huh? ???](https://www.ihadav8.com/forum/Smileys/default/huh.gif)
![Huh? ???](https://www.ihadav8.com/forum/Smileys/default/huh.gif)
? Or return it for an exchange at point of purchase.
The instructions had the GN covered and explained where to tap into the tach signal so i think its compatible.