2000 outback ls tachometer

Brand new to forum, brand new to boating.....
I just bought a 2000 outback ls, all is good. boat runs great and didn't sink after parking at baldridge marina. The only real problem , if you can call it that, is that the tachometer does not work. Yes, I may be a little on the perfectionist side but, I'd like to know how high I am spinning it up. Does any one have any input on what the problem could be? The light on the gauge works and the hour counter works. I checked all of the "plugs" on the back of the tach with a tester and figured out that the only wire that did not light up, with my rudimentary tester, was the yellow wire.

Is this a wiring problem or do I need a new tach? If I do need a new tach, where do I order one online?

Thanks, in advance. for all o your input and help.

I'm not much help but my 1998 has an occasional problem of the tach reading too high but a couple of thumps on the bezel fixes the problem. It may be difficult to find a replacement so I would recommend a seperate tach. Possibly a digital in a 2" round. It is important to have the tach especially when the speedos start messing up.

Does this one match?

http://www.ebay.com/itm/Skiers-Choic...0db78b&vxp=mtr