tach problem repost

[Vatche]

ok so ive asked this before and i always get someone telling me, "oh thats easy ill fix it for you" 3 times thats happened and three times i got nothing in response from them....

my problem is i have an 89 coupe with sr tach and usdm hud cluster....the tach idles at 0 and revs up when im driving but totally off....i know there is a way to fix this problem ive heard of ways from people....but i still dont know what exactly the fix is .....and i dont want to pay someone 200 bucks to fix it when it can be fixed really easily any help will be appreciated.....understand this problem bothers me and im not jdm superstar electrician. dont get upset and call me stupid for not searching because i have i dont ever find anything