Just got my new tach board in the mail today.
Here’s what you get when you order a new tach board for the 86-88 V6’s. (see pic below)
This is being installed in my 85 GT, which was upgraded to the 120 Speedo and aux. gauge pkg. years ago. The reason for the tach swap is my current one is showing +500 rpm than is actual. (as verified by my Scantool program) Also, I know that some modify/adjust/recalibrate the old one but I felt it was wiser to simply go with a new one as the components are “fresher” than the original ones, which are fast approaching 40+ years now.
I’ll be getting started in a few days and will post pics along the way.
And, to verify that the new one is calibrated correctly, I’m going to run my scan tool program before I put the instrument cluster back in its place. Kit

[This message has been edited by Kitskaboodle (edited 05-19-2025).]

I rotated the image for you Kit...



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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

[This message has been edited by Vintage-Nut (edited 05-19-2025).]

i used one on my 1987 2.5.it was way off before.it agrees with the scan tool now.

Please let us know how it goes?
I will need to replace mine sometime as I've already done the repair with a variable resistor many years ago to recalibrate the reading.
But now the tacho just dies intermittently, especially on a hot day.

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"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM

I just installed mine. Realized there were instructions after I finished. Works great.

Ok, I made a lot of progress today. Here is what I have done:

1) Removed cluster pod and put it on my workbench.
2) Removed instrument cluster from pod assembly.
3) Removed clear plastic bezel and black/orange cover plate from cluster.
4) Removed speedo assy. from cluster (white) housing. (pulls up & out / no screws to undo)
5) Removed screws that hold in tach assy., carefully placed my fingers under the tach and lifted tach assy. up & out of the housing.
6) Removed old tach board from the back of the tach gauge round can metal housing. (3 standoff screws)
7) Installed new tach board onto tach gauge round metal can housing.
8) Installed tach board assy. back into cluster white housing.
9) Re-installed speedo assy. back into cluster white housing.

Important suggestions & notations:
It pays to be thorough & detailed when taking apart 40 year old stuff. Here’s why….
Notice in the pic above that I have some green corrosion on the copper traces of the connector that is on the left (drivers) side of the cluster. (not sure if you can really see the green corrosion but it’s there on the first and last pins) I will clean this up but my point is to examine stuff when you take electrical connectors apart.
Next post will address a change I made to the Speedo pc board.
P.S. See that plastic doo-dad at the lower left of the pic? It’s kind of “T” shaped, has a single plastic post that snaps into a hole and is meant to hold a loom of wire in place? What do you call this type of fastener? My Reatta uses these also and I could never find them on Amazon. I know what they’re for but I don’t know what you call them. What specifically are they?

[This message has been edited by Kitskaboodle (edited 05-20-2025).]

quote Originally posted by Kitskaboodle: On a different note (and in a different thread) we were all talking about the Fiero shift light and which clusters had the shift light capability and which ones didn’t.

I don't like those nasty SHIFT lights!

Ok, I have finished the project.
It turns out that it’s a good idea to double check the accuracy of these new tach boards before you button everything up. Mine was about 75 rpm above what the computer said. The good news is it’s quite easy to adjust/calibrate it while the engine is running. It is adjusted with a very small flat head screwdriver at the blue
potentiometer at the bottom of the tach board. See pic of the tach gauge in the cluster (installed temporarily above the steering column) but without the template/cover.
Kit

[This message has been edited by Kitskaboodle (edited 05-22-2025).]

quote Originally posted by Kitskaboodle: The good news is it’s quite easy to adjust/calibrate it while the engine is running.

Care to elaborate?

I was editing my post with this very info but you were quick on the draw. 😊
Kit

quote Originally posted by Kitskaboodle: It is adjusted with a very small flat head screwdriver at the blue potentiometer at the bottom of the tach board.

Thanks Kit, that's good to know.

The tach in my '88 GT used to continuously spin erratically. I Installed the same board you did and the readings seem within reason out of the package to what other V6 Fieros I have had in the past. Good to know it can be calibrated though.

Forgot to point out that unlike the Cajun tach board, the factory tach board has no provision for rpm adjustment. (another reason to go with a new tach board)
Also, if you’re going to go to all the trouble of pulling your whole instrument cluster out, remove the gauge assy., then swap out the tach board, you might as well go the whole distance and check and/or tweak the rpm’s on the new tach board. In fact, the instructions imply that you might have to do this anyways. Kit

[This message has been edited by Kitskaboodle (edited 05-27-2025).]