Question about 1984 Pontiac Firebird

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Tachometer stopped working on a 1985 Trans Am

Puchase another Cluster from the same year car with same 305 H engine fro a very reliable source of parts that I have bought from before.

Tachometer works, but is inaccurate. Normal idle is aroung 7000. Its shows 5000 higher that what it really is.

Any ideas ?? I have heard some talk about a Tach filter, but I thing 1985 was too old for that. I heard a tach filter was for new birds.

Thanks
Rob

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  • yadayada
    yadayada May 11, 2010

    check the distributor cap pickup

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6 Suggested Answers

6ya6ya
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Posted on Jan 02, 2017

  • 46 Answers

SOURCE: speedometer and tach

With the key in the off posistion press and hold the trip odometer reset button, the lights in the cluster will start to flash and the guages will do a self test. This should take care of your problem.

Posted on Aug 30, 2008

mrgreenz
  • 962 Answers

SOURCE: 1967 Pontiac Tempest

Have you replaced or removed the battery before this happened ? if so disconnect the battery and let it sit for a few minutes. Reconnect the battery and it should reprogram the computer system. I am not completely sure if your car has an instrument cluster fuse but check inside the hood and the fuse panel box.

Posted on Nov 02, 2008

tommyboinow
  • 324 Answers

SOURCE: tachometer gauge

your relay is going bad, replace it.

Posted on Nov 26, 2008

Bat1956
  • 585 Answers

SOURCE: Install aftermarket tachometer

I'll take a stab at this, there's better than a 50-50 chance, and you can do no damage if the first try is wrong. Red is +12 volts and Black is chassis ground. that's a given. I would try Blue to coil pack "Tach" terminal, and Green for the dashlight. If I am right about the Blue and Green, a 9-volt battery from Green to Black will light the light if it's not burned out. If the Green doesn't light it, try the Blue, but my bets on the Green. If the Blue doesn't light it either, the bulb is toast.

Posted on May 08, 2009

  • 1 Answer

SOURCE: tach stops working and trac control light off comes on

It sounds as though your Crankshaft Position Sensor has gone out. They are pretty easy to change. You will have to remove your harmonic balancer/crank pully to get to it, as it is on the inside of the pully. Also, if you have a 3.1 engine, you have a second Crankshaft Position Sensor on the side of the engine closest to your firewall. (it is below the number 1 and 3 spark plug). It could be that one or the one behind the balancer. I would suggest replacing both of them at the same time. As for removeing the harmonic balancer, you should use a puller to do so. When reinstalling it, do not use a hammer or anything to tap it back on, as this can damage the balance and also the crankshaft. You should use a harmonic balancer installer to put it back on. Both the puller and installer can be borrowed from Autozone (with a deposit that will be returned once you return the tools).

Posted on Jul 22, 2009

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