OkeeGuy

ok...heres the rundown...
tach started acting wierd...you know...OCCATIONALY jumping around for a bit and then acting normal...
then, almost day by day..."occationaly" became more frequent...
until it seemed as tho it was wierd more often than it was accurate...
so i broke down and bought a brand new circut board...
WALAH! it was absolutly perfect again! for about two days! :rolleyes:
it was a couple of days after installing the new board that i was driving around enjoying the bliss of my nice, steady, accurate tach when i looked down and saw it jump... :mad
DAMN! i thought...that sucks! even tho it only did it a time or two...
next day...fine...as a matter of fact it was good for a few days...
and then...you guessed it! jumping arond almost as much as it used to!
so i call the guy that i bought the board from and asked him what he thought and he suggested removing the tach filter saying that its only purpose was eliminating radio noise...ok...
so i did....
you guessed it! NO DIFFERENCE!
so now i have no filter and a new board and its acting about like it did before i started trying to correct it...
some days its fine and some days its not...
some minutes its fine and the next minute its not...

any ideas or thoughts about this?

LAvetteman

Bad connection somewhere, probably not in the board.

SizzleChest

does anything else read "oddly" like the voltage meter? Mine was doing that before, but almost every other gauge was off as well. It was a bad connection from the starter. Also make sure you're battery posts have a good solid connection.

Ric's80_4sp

I had the same problem with my 80. The problem for me was the driver's side power window switch located in the shifter console (last place I would have looked!). I went to replace this switch after it broke and found a factory bolt that was attached from underneath the car and came up through metal floorboard. Don't remember why the bolt was there. Anyhow , the bolt was directly under the switch. The switch has 3 pins and the "hot" pin is longer than the others. This longer pin passes through the factory wire connector and is exposed. This left a very small gap between the bolt and pin. So when the center console would bounce around while driving the pin would hit the bolt and ground out. This somehow would short the tach causing it to "jump" around. I trimmed the bolt down and placed a plastic cap over the end. So far I have no problems with my tach.

Hope this helps!

OkeeGuy

thanx for the advise guys...
ironicly, yesterday after fueling up my car wouldnt start...
wouldnt even click the celenoid...
when i reached in and "wiggled" the battery cables, sure enough, one of them was loose! i wiggled it and it started right up...
so now im wondering.....HHHMMM?
i planned on tightening it up today so we will see...
man! that would be great if thats all it is!
which probably means that i didnt even need that circut board... :rolleyes:
oh well...
ill let yall know...

LAvetteman

Don't sweat it to much. You gave that tach board a shot because it is a common failure. Meaning, you will probably need it eventually anyway.

OHSIXX

Hope you get your tach straighten out!

Just wanted to let you know I was in your area the other day. Saw the sign that said "Okeechobee Road", but had to go the other way. :)

OkeeGuy

you were probably down West Palm Beach way?
im actually in Okeechobee city...about an hour northwest of there...

well i tightened the battery cable today and although i only drove it about 10 miles after work, it was rock steady and correct...
the real test will be time and miles but ill let yall know...
a lot of people have this problem so i think its worth reporting back to yall on.

Fast81

Signguy - also be sure to check the tach wire from the distributor, mine started acting up too and I found I had pinched the wire when changing a plug wire. Straightened it out and the tach has been rock steady since.

OkeeGuy

well...about 20 more miles and still steady!
rock solid and dead nuts accurate!
this might be good info for anyone having this problem...
BTW...i report this with all fingers crossed as we all know what could happen at any moment!
:lol: :rolleyes:

HEARTBEATUSA

Hey Signguy,
If the original board is o.k. I'll take it off your hands... that is if it would fit a '76, let me know if your interested in selling it,
Tom :cheers:

OkeeGuy

i dont know if it will fit a 76...
anybody???

LAvetteman

NOPE.

3 different tach circuit boards for C3's.

75-77
78-79
80-82

OkeeGuy

well...there you have it! sorry...
BTW...tach is still working great! not even a glitch!
if yours is acting strange...check those battery cables! :yesnod: