multifunction tach gauge manual

does anyone know where I can download a manual for a tach gauge. It is one of the older gauges that don't have any buttons on the front and has only 2 swithces on the back.. I have it all rigged correctly but I am not sure on how to read it and what it means.. I know the trim,rpms it is the 3 at the bottom..yellow low oil, pink/red temp, and green?
thanks

[boats.net]

The three lights at bottom are oil level, green is full, yellow add or low oil and red means no oil in oil tank.