Topic: No Tahometer Reading
in Forum: C3 Electrical
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mount airy, MD - USA
Joined: 8/27/2006
Posts: 71
Vette(s): 1981 Charcoal Met., Silver Interior, Gymkhana Suspension, 27K original miles. It's my daily driver.
I know this question has probably been asked before, but I can't find the answer I am looking for. Is there a fuse that affects the Tach operation and nothing else? If so which one should it be. I am in the process of getting service manuals. Everything else on the car seems to work fine , except defroster door operation. Tach does nothing at all. No movement whatsoever. Thanks, Tom
1981 Corvette, 26K original miles, charcoal gray, gymkhana suspension, AM/FM/8 track.
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Others will chime in, I beleive the tach signal comes from the white wire at the distributer, through a tach filter to the instrument circuit board connector. You could check the connections at the distributor and bypass the tach filter.
Sounds like a bad tach board. But first make sure it's hooked up. Has it worked while you've owned it?
At the rear top of the intake manifold you'll find a capaciter(filter). Follow the wires, one to the distributer and the other to the wire coming from the tach. If OK, disconnect both wires from the filter and plug the wire from the tach directly into the distributer bypassing the filter. If that helps, bad filter. If not, most likely bad tach board.
Low mileage has nothing to do with board longevity. I've replaced the one on both my Pace Car and white 79.
30 minute job on 78-82s! Get at it from the front.
Remove the clear lense fom the gauges, 3 SHORT screws at the top of the window and 1 each side. 6 allen screws removes the black bezel. 3 screws removes the tach. On the back of the tach you'll see the board in question.
Most of the vendors sell the replacement board. I've gone with Mid America, about $60.
Remove the old, install the new making sure the fibre washers are in place. Install the tach and 3 tach screws. Turn the ignition to 'on' and see if the needle zeros out. If not, carefully pull the needle off and reinstall it pointing to zero(with the key 'on'). Handle gently, the needle is very fragile!
[QUOTE=rraider1]... You could check the connections at the distributor and bypass the tach filter...[/QUOTE]
I agree. Check the connection at the distributor. They can get dirty and/or wiggle loose.
in Forum: C3 Electrical
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