Tachometer problem

[Z282NV]

Ok, gonna post here first, then use this for a post on third gen. org.
Stock tach on the 85.... Got another one.. Tach is not the issue.
Heres what happens. When you turn the ignition to "on" without starting the car
the tach slowly climbs to pegline 7 grand....
Turn the ignition switch off, tach remains at 7 grand.
The oil pressure guage that is w/ the tach is fine.
When you start the car, The tach automatically jumps to 7 grand or peg redline.
Sounds like an electrical short. I realize that I only have to have hot and an ignition to run the tach. My question is, how can I test the factory connection wires at the distributor. There are two wires that go to the distributor, both are marked on the cap. This is the same exact problem I had with the old tachometer.. Its like it has a short in the wire some where I suppose. What can I do? I would really like to get all the factory guages working but its getting less likely each day.

[Rarerat]

I don't know on that one, is there a break in the wire somewhere that is grounding?

[Z282NV]

I hope its that simple.. Hopefully Ill get a chance to look at it soon.

[DvBoard]

Did maybe a capacitor go bad?

[67 LS1 Vert]

flux capacitor? lol j/k

Look at the wire at the bottom of your tach and see if it plugged in all the way. Never know, it might be barely making contact?

[Z282NV]

[Z282NV]

Heres what one member told me:
The problem is in the circuit inside the dash that moves the pointer.

It’s contained on a small plug-in PCB or integrated in the main board.

On the PCB you’ll see a resistor chip.

Desolder pins 4 & 10.

Use a 500K potentiometer.

Solder it across traces 4 & 10.

Move the potentiometer to half way.

Start the engine and compare the tach reading with a test equipment quality tach.

Dial it in, unsolder one side of the potentiometer, measure it and install a matching resistor.


Sounds like to me it would be easier to replace the whole cluster. But when you do that, you get into speedo reading issues....(**^*&^*&*!!!!!!!!!!!!!!

I have 6 guages total on the camaro.

1. Speedo
2. Gas
3. Volt
4. Oil Pressure (mounted on top of tach)
5. Tach
6. Water temp

of these 6, only 3 freakin work.
The speedo (makes rattling noise I guess cable needs lube)
The Oil Pressure
and the gas guage works....crap!!!

[67 LS1 Vert]

Just get a different cluster and roll the speedo to what your old one says. Easy cheesy. On the back of your speedo, there is a black tab that has slots cut in it that hold on the seperate dials. Carefully remove that and spin the numbers to match your old one with out touching the black numbers. They will mark up really easy.


















Do at your own risk. All info typed here will self destruct in two days.

[Z282NV]

I think that would be the less labor intensive. Thanks!