Wiring-up Yamaha Tacho

[spartacus]

Hi

I've purchased a second hand Yamaha Tacho analogue (not the newer digital multi-function one) and plan to install to the steering console of my Zodiac Pro. This will connect to a Yamaha 2-stroke, 3 cylinder, 40hp autolube engine (1995). It's a manual start engine.

The tacho is illuminated and there are electrical spades (blue and brown wires from the bulb) which are already there. This is straight forward enought to connect up, and I can wire up via my navigation lights.

There are 4 terminals on the reverse of the tacho (the indent markings on the plastic read 12, B, 4 and G. I assume G is the earth as it's separate from the other three terminals? Not sure if 12 is 12 volt supply?

It might be easier to send a digital picture to a forum member - who's familiar with wiring in instruments. Just need to know what the wiring configuration is.

Any advice greatly appreciated.

Thanks

Spartacus