MY tachometer just stopped working....

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Jun 18, 2006 | 11:48 PM

RED-85-Z51

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MY tachometer just stopped working....

Its been acting funny for a while, at least a couple of months. It would go to the redline, thne to 0, then move back and forth randomly...

Now it just always reads 0, it lights up, everything looks okay, it just reads 0.

Its the only one of the gauges that isnt sunburnt..and now it stops working...fantastic!

Any Ideas here? I havent got a clue where to start...

1985 Corvette

Jun 19, 2006 | 12:17 AM

Redeasysport

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From: Myrtle Beach SC

St. Jude Donor '05-'06

Get you FSM out and use the flow chart.My GUESS is the tach filter is bad Or a loose wire or bad guage.

Jun 19, 2006 | 01:47 AM

CentralCoaster

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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed

There's one white wire running from the distributor to a tach fillter behind the head, then into your cluster harness. It's most likely loose at the distributor.

Jun 19, 2006 | 09:40 AM

RED-85-Z51

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Thanks, Ill check it out.

Jun 19, 2006 | 09:52 AM

rick lambert

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From: seattle WA

In Gorodn Killebrews book he says the most common problem with our C4s tach is water in the bulkhead connector..by the steering column, the tach pin is in the lower row..seems the general didn't seal the top and side of the connection. If you pull it and see a greenish/whiteish look, that indicates water, just blow it out, leave the black looking grease, it's an anti corrosive grease.He also says to seal the top and sides and make sure the cowl drip tube isn't dumping on it.

Jun 19, 2006 | 10:40 AM

CentralCoaster

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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed

Hmm. Mine might not drip on it if GM didn't put the damn thing there. Also is right below the clutch master, so it sees some brake fluid too. I've been ok so far...

Jun 19, 2006 | 12:54 PM

RED-85-Z51

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What is this Tach Filter?

The wire was in the slot, didnt see any corrosion.

Jun 19, 2006 | 08:26 PM

CentralCoaster

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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed

Quote:

Originally Posted by RED-85-Z51

What is this Tach Filter?

The wire was in the slot, didnt see any corrosion.

I think there's a little bracket that attaches to the backside of the drivers side head, hidden under the wiper motor. The tach filter should be here.

Better yet, get an ohm meter, and check for continuity from the distributor plug to the harness under the dash. Where the bundle comes through the firewall, there's only maybe 2 white wires in that whole bundle. The small guage one is the tach wire. You may need to remove some tape in order to get enough wire loose to jab it with your ohm meter. Not sure if it should show up as continuous, there is probably a capacitor in the tach filter, but it should look different than an open circuit.