Broken tach

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Mar 11, 2017 | 08:10 AM

ImBatman

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From: Lake Wylie, South Carolina

Broken tach

The tach in my 1990 base coupe was erratic and then just dropped and no longer works. When it dropped it went completely below 0. Not sure if that matters.
Is this a cluster issue or is there something else I can check?

Mar 11, 2017 | 08:24 AM

WVZR-1

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Quote:

Originally Posted by clovergamecock

It's nearly always a cluster issue BUT if maybe with a complete failure of the wire at the filter is physically broken some where or maybe it's actually only disconnected at the distributor. Have you done any under-hood maintenance recently? Cap/rotor wires or ...

With KEY-ON but not running does the needle park at 0 or below? If the tach/cluster calibration isn't flawed it should park at 0. A total failure of the signal wire to the cluster I've never experienced. With a hand-held device you could check before the filter for an RPM and then after the filter but before the cluster.

Last edited by WVZR-1; Mar 11, 2017 at 08:28 AM.

Mar 11, 2017 | 10:47 PM

ImBatman

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From: Lake Wylie, South Carolina

I changed the ignition module a while back but it was messed up before then. The needle doesn't move at all even when you first turn the key. It stays all the way at the bottom below the 0

I have some lights out and incorrect gas Guage anyway so I guess I will pull it and send it out for rebuild.

Thanks for the reply!
Wade

Mar 12, 2017 | 06:21 AM

WVZR-1

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Quote:

Originally Posted by clovergamecock

Bulbs are a DIY and seldom is the fuel a cluster issue. You were in the distributor so I'd think the first check is the connector at the distributor and confirmation of a signal to the cluster. Rebuild doesn't correct "foolish"!

Mar 12, 2017 | 09:21 AM

ImBatman

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From: Lake Wylie, South Carolina

Quote:

Originally Posted by WVZR-1

So if I'm "foolish" do you have any suggestions on the fuel Guage issue if not related to dash? I have already pulled the pump a lightly sanded the surface the sending unit rides on for sending the signal.

Mar 12, 2017 | 10:45 AM

WVZR-1

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Quote:

Originally Posted by clovergamecock

It's a 100Ω gauge so if you supply 0 - 50 - 100Ω you could expect EMPTY, HALF or FULL (or close to). If it's at or near those values then I believe you could assume no issues with dash unit. Fuel gauge on a '90 I believe also relies on communication from CCM.

Mar 20, 2017 | 06:57 PM

corvette95

Melting Slicks

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From: Decatur, Alabama

yeah, probably cluster but could be coil. Vetronix makes a special tester if anyone near has one. With your year you are going to have to pay to have miles and vin burned in to make it correct too. Extra$$$

Mar 20, 2017 | 09:23 PM

FOURSPEEDVETTE

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From: Pennsylvania

When I had this same problem, I changed the tach filter. It's a small in-expensive cylindrical part mounted behind the driver side valve cover between the block and fire wall on my 85. I just cut the wire to it because it's too hard to get at and remove back there. No one can even see it buried back there. I installed a new one and attched its mounting bracket to the thermostat housing bolt. It's a very small part and blends in fine mounted there. Works fine now.