ok guys I just installed my autometer tach and cant seem to get it to work right
the tach seems to be ok until 15-1700 rpm then it starts to flutter just a little up to 2k if i turn the lights on it goes completely crazy and wont read higher then 2300 it will read 2700 with lights off and if i have it in neutral and rev it up it will read real steady all the way up to 3500 as long as light in tach is off ,but put it in gear and drive it and it goes nuts and only reads 2300 .I triple checked the wiring instructions and the only thing i see diff. is my altinator has no laminations to set pick up on. anyone have this problem ? sure could use a clue

 

sounds like a crappy ground scource or the pick wires are ran to close to something else... jiMMy

 

I do not have the exact same problem but I do know when I am sitting idle and turn on my directionals, I see my tack jump a little with the blinking of the signal. But never have had a problem while driving down the road. I forget whose tach I have (without looking at it) but mine is connected directly to the Tach's connector under the dash compared to the ALT.

It does sound like a grounding problem or wire to close to something picking up that signal.

 

ill recheck the ground and see if the pickup wires are not neer any thing
thanks

 

I had a simalar problem with my Pyrometer. I wound up powering it (using a relay) direct from the Battery to cure the problem.
My Pyro (Autometer) would work fine untill I turned the lights on or pulling a trailer , then finaly when I was breaking. The needls would bounce or ped negitve. The relay fixed though.

 

well i checked the grounds and all the wires and found it will only do it with the tach light on if i unplug the tach light it stops ran a seperate set of wires for the light and it still does it works fine as long as light stays off think ill try and pop the light out and see if it still gos nuts

 

On a 1990 what would you hook the tach pickup lead too? Is there an electrical connection somewhere under the dash? Or do you have to tie into something under the hood?

 

the autometer 2888 tach has a electical pick up that hooks to the alt. and you need a real good ground or it will go nuts
i had to run 1 all the way to the battery

 

so it works now?? awsome!!!