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Tachometer troubleshooting

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Old May 5, 2005 | 11:57 PM
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Jim W's Avatar
Jim W
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Default Tachometer troubleshooting

The tach on my 79 died. It was working erratically (up to 3500 rpm then bounching backword) but now it is dead. No response when I turn on the key. I have searched the Corvette forms and my books but I can’t seem to find a troubleshooting guide or a wiring diagram. Should there be a condenser/filter on the intake manifold near the distributor?
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Old May 6, 2005 | 12:59 AM
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ACECO
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The tach filter should be bolted to the drivers side rear of the intake manifold. Looks like a filter condensor but has a couple of parts inside. You can test if it is bad by simply bypassing it and see if the tach starts to work. If so then you need to replace the filter as it is there to protect the tach circuitry from electrical spikes although many seem to be running w/o one w/o any issues.

Tach filter circuit shown below. If you needs the parts to build one, I can provide them if necessary.



Good Luck!

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