Tach Fix

[StereoInstaller1]

I really wish I had taken pictures of this project, but if your tach is flaky...not weird, bouncing all over, but works when it feels like it, but generally doesn't, try this:

Take your instrument panel out and apart. Pull the tach and the temp guage, and resolder all of the connections on the blue plug.

Took me like an hour, but I have a working tach now.

Luke

[Jean]

Had a similar issue related to a bouncy temp gauge, it was bad/cold solder joints on the board.

[Japandrew73]

so if my tach reads incorrectly all the time, meaning it always reads from 0k-3k whether i'm redlining or not (running like its being resisted). It reads 2.5k when it should be around 5k (i know the sound of my engine), if I have this solution, and I re-solder all the joints, it should work?

And you mean all the joints right?

[Jean]

Probably not.... what is the condition of your si board? if you cluster is the original early style you can bypass the board completely by soldering a small jumper wire on the main board in the cluster. I've ran like that for months until I got a good si board.

[Japandrew73]

My SI board works perfectly fine! That's the weird part!. Well... I think it works fine. I'm not sure how long it's supposed to take for one light to go out on it, but I started out with 3 green lights, it's gotten to 1 green light as of now and I've had it for about 5 monthish.... sound about right? What could the problem be?

Also the temp guage is a bit iffy (bouncy) and the fuel gauge is simply off. It goes way past the empty point but the light lights up when i'm on reserve fuel thats how I know i'm out of gas

[Jean]

Could be many things since it's like 20+ years old. To check the fuel gauge you can remove the rear seat, and disconnect the fuel level sender harness. Look up the thread where readings vs. ohm table was posted, then you can make do a "gauge sweep", and see if it works (if it works, then it's your sender in the tank, if it doesn't then it's the gauge or cluster). Temp gauge, can disconnect the sensor under the hood and do a "gauge sweep" as well (open/short circuit) to have it go to 0 or maxed out. I assume you already checked the cluster board for bad joints and the two nuts at the back of the cluster aren't missing etc. Can also remove the gauges and clean the contacts.


Tach... I don't know. Pick one up from a yard and replace?

[norcalE30]

okay this is good, because my tach, water, and gas gauges work when they feel like it, so does the light on the tach side. sometimes if i smack the cluster they pop on. should i just pull the cluster and re solder all the connections?

[Slangbox]

^^ Swift karate slap to the back of the top of the cluster does it almost every time.

Then, of course, sometimes it carries on not working for a day or so. 22 year old win.

[Japandrew73]

the light on the cluster is just a bulb needing to be replaced most of the time. before those bulbs die, they die and when you hit them they drain the rest of the power and go out, and hit them they drain some more power, etc.

[Jean]

lol "they die and when you hit them they drain the rest of the power and go out, and hit them they drain some more power, etc. " that's almost quote worthy Andrew!

[Japandrew73]

lol "they die and when you hit them they drain the rest of the power and go out, and hit them they drain some more power, etc. " that's almost quote worthy Andrew!

hah what it's true!

[StereoInstaller1]

All I know is my dash lights are brighter, the fucking tach WORKS and now I have to do some actual calibration of the temp and fuel gauge.

I might even go and fix the damn OBC. It works, but no light.

Nah, gonna do strut mounts (if i can find the extra dough) and install the set of tie rods that I got over a year ago....and the new front subframe I have had for 3 years, and the cabriolet sway bar, and M3 endlinks.

SO happy to have a working tach again!

[StereoInstaller1]

As a side note, the stupid MPG gauge works now, too.

[ikkitousen]

Okay then I have a question for you guys. I just swapped that M20B25 into my eta and everything is working cept the tach, econometer and the OBC (just reads the same mpg etc, but temps are good). I swapped to the 173 ecu when I changed to the '90 I motor, made sure I have new ignition wires with that 7th tach lead on them.

Sooooo, if the tach and econometer are "caputz" in the cluster but the tach "hicups" to about 500 rpms when I turn the car OFF. What does that mean?
Bad SI Batteries? I just changed the cluster as well to a newer "used" one and I dont think it was sitting around unpowered for more then a couple weeks. The old eta cluster had a bad speed sender error code and the tach didnt go to 6500 rpms anyway (well it didnt move at all after the swap, so I figured it was a bad SI board). I know this new IS tach is the same motometer and all the plugs lined up and everything else works. I could care less about the MPG guage but I really want that tach to work.

On a side note; that OBC back light is out as well on mine Stereoinstaller, so I need to change it as well. You wouldnt have a part number on that bulb would you? I haven't looked for one yet, thought maybe you might know.

Thoughts?

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DAMN BENTLY MANUEL DOES NOTHING!!!

[StereoInstaller1]

I know that fucking bulb is like 8 volts or some goofy shit...ask James Crivellone.