No Tachometer

every since i bought my 90 rt i've had no tachometer, it's always been dead. has anyone heard of this problem or know of an online source where i can find wiring diagrams for the tach?
thanks
thanks
Comments
Just google "Honda Service Manual" or something
this happened after i washed the engine bay a long while back. i thought it might be my dizzy getting water in it, so i swapped it with a spare one. nothing changed.
maybe the tach itself is messed up? i never bother to check that with a spare one.