tachometer question

[355shortbed]

i bought a used autometer pro comp II tach from a friend and i ran same color wires as on the tach,( i have OCD) ,one to a key on positive power source(red), one to lights (white), one to neg. side of distrid. (green) and one to ground under dash(black), when i first turned the key on it went to 0 and then jumped backwards pointing to the recall and light bulb on the tach. and thats where it stays, even when i cut power to it. when i hit the recall button it jumps up a little bit and will stay there.  what causes that? polarity backwards maybe? i dunno any answers would help. i checkd voltage putting my prongs at the red wire and the black wire and it gets up to 14v . i looked on autometers website and i cant find any help
-The only thing that works right is the lights lol.

[VileZambonie]

Do you know if it worked when you got it? Make sure your green wire is hooked to the tach lead. Check your connections again. If it still doesn't work make sure it's calibrated correctly. Did your friend have it on a V8?

http://www.autometer.com/productPDF/1244.pdf

[355shortbed]

yeah it was on a v-8, i rehooked it up today and it worked for a good 2 minutes then started doing the same stuff , so i reckon somthing came loose. It worked when he pulled it off his truck, supposidly..