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Tach needle is sitting between 4&5 K
Maybe a bad ground? does not seem to move.
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My 78SA was stuck at 2500. Took off the clear bezel; 3 short screws across the top, 1 on each side; and gave the needle a little nudge. Works fine now. Probably from minimal use in my case.
Otherwise, maybe a new tach board. Tach comes out from the front. With the clear bezel out, remove the 6 allen screws around the black gauge bezel. Remove that bezel, 3 screws hold the tach in.
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Send PMGreensburg, IN - USA
Joined: 9/24/2003
Posts: 5387
Vette(s): Previous: 1984 Coupe, 1988 Maroon Coupe, 1989 Coupe, 2001 Roadster Present: 1967 Stingray Roadster, 1976 Stingray Coupe, 1989 Roadster..
Thanks Mike..... I thought it had to come out from the back. Mine is hopefully stuck too. I been puttin it of until winter because I thought it was going to be one of those afternoons sent in compromising positions laying on the floorboard. 
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It could be a stuck needle, a bad tach, a bad tach board, or a bad connection from power or to ground.
Does it move at all when the key is cycled on and off?
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Ken, when I shut it off it comes back to maybe 3. then when I start it moves to 4-5 area. Reving engine does not make it move.
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If it moves it's not stuck.
Which Vette? The low mile one? Try swapping it with your other one. 30 minute job to remove it.
Sounds like the problem my Pace Car had, bad board. There's a guy over on CF that repairs em as long as it's not the chip. I'll get the info if you need it.
Tux, unfortunately, yours comes out from behind!
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Thanks Mike, I'm about to get the project car in position in the garage. I'm not sure if that ones works. I'll check.
I'll reach up and check the connectors if I can reach them. But I'll take the info any how just in case.
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If it is responding at all it has power, and ground, and is not stuck.
kstyer 2008-07-05 19:00:19
It seems to respond to the tach signal fromt he distributor, so that is probably okay.
That leaves the board and the tach itself. Mine acted the same way, and I replaced the board. Then it changed but still acted badly. After low rpm it would go all the way to the max. The tach had a bad coil, as well as the board failing.
I got the board from Bair's. It came with a slip from the man who makes the boards. It said if you still have problems send him the tach. I did. He repaired it. Now all works properly.
He is
J. Gardner's
Electronic Tachometer Repair
4874 Bowood St.
Center Valley, PA 18034 610 797-4048
Nothing like going straight to the source. You can send him the tach and the original board, and he will send back a working unit, whatever it needs.
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This guy's in NJ.
I would imagine you could email him through the CF site.
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Thanks Ken, I can swap out the project tach like Mike suggested and send the bad one out for repair. 
Life is good.......
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in Forum: C3 Electrical, Body and Interior
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