I have replaced my distributor[old one was bad] an alternator with new parts.I had a problem before replacing
them that didnt get fixed by the replacerent.The rpm guage is erratic, sometimes working other times acting crazy,sometimes doesn't move.
What do I need to look at?
There are no more codes now .I was having 02 an ELd but fixed those.
There is a slight buck or hesitation once in a while at 1st acceleration in drive though ,but not very often.

 

You need to provide car information.

 

It's a 96 civic sedan non vtec automatic

 

Stock D16Y7 engine and stock ECU?

Any modifications?

 

RPM gauge = tachometer

 

Original tach

 

Will I need to test that blue wire from dizzy to cluster?

Tach wire

 

Swap in a new ICM. Return if problem persists.

 

Problem persists w new one..
There is at times a engine thump or hesitation after going ahead from a stop sign ,only that moment at acceleration at 3 mph or similar.sometimes .its not often but I'm wondering if that factors it an what all to check.[timing is fine]..
I checked all grounds too,tune up ,fuel filter,etc.

 

Is the fluctuating rpm a recent problem? When was the last time you did a full ignition system tune up (plugs, wires, cap, rotor, ignition timing)?

Do you have an OBD2 code reader that reads live data, such as engine rpms? If so, it might be informative to check whether or not the code reader shows the fluctuating rpm of the tachometer. If the code reader shows steady rpms, then the cluster tach may be bad.

Have you checked whether 7.5A dash fuse 15 is blown. When you turn the key to ON(II) (engine off), does the cluster charging system warning light remain on steady? Shorted wires on the back of the intake manifold (fuse 15 TSB) can sometimes cause odd tachometer behavior.

 

Did a full tune up recently with distributor an alternator an no changes on it set timing also.. Started a while back when cps code was coming up

I'll try testing rpm w elm327 obd2 tool .
but it's like it has a mind of it's own or a short..sometimes ok ,other times dead ,othertimes way up at the 7 when cruising an a drop in it w no change in speed.
Did a ohms test for any shorts an they were fine .at dizzy an behind cluster..
I saw a test port off to itself also with 1 blue wire..

 

 

Yes it's working fine an alternator charging 13-14.
lights go off as usual .no blown fuse

 

You can either do more testing or try swapping in a known good tachometer.

 

If you do the test I suggested, the charging system warning light in the cluster should stay on steady.

 

Yes its steady.
What's the next test to try..that cluster test?
An is the test port I saw at fender corner drivers side at dash for a dealer to hook up some tester they use to check it?

 

 

I mean it comes on with the regular car start system test as other lights do.nothing after that..in other words nothing stands out .
-no codes either

 

Plug a scan tool into the OBD-2 service port and select "live data" on it. Monitor the RPM/Tach value on display and take the car for a test drive. When the tachometer begins to fluctuate as you have described, see if the values on the scan tool mimic what you see on your instrument cluster. If not, your problem is not the rest of the car, but simply the tachometer in your instrument cluster.

 

I agree with JRCivic1's last point. It sounds like everything is functioning fine up to the cluster, yes? Like, your RPMs aren't actually all over the place, it's just the gauge misreporting. This could be a short going into the cluster, but in my experience this is the telltale sign of a cluster on the fritz. These problems start out intermittent but eventually you'll be left with completely dead instruments.
I hear muellersfan suggesting swapping a different tach into the cluster- that seems crazy to me. Are you not worried about the tampering warnings?
I will not work on my own cluster, I want to have a paper trail from a certified shop for anyone touching that. Thankfully there are a few independent shops who are equipped to do the necessary cloning properly. Personally I recommend these guys as the deal exclusively in clusters. https://www.instrumentclusterstore.c...t_clusters.htm

 

What? JRCivic1 is simply agreeing with my earlier post:

And I'm also pretty sure you're confusing a tachometer with a speedometer.

 

I did a few things to test it.
READ RPM to my bluetooth elm tool an my tool is correct but guage isnt.
I tried that 5 step reset cluster test just to see if it changed anything and also tried the reset button in -on maintinence light-an no light came on..there was no " swing" of the needles.
ODDLY AFTER doing both these tests the TACH WORKED LIKE A CHARM an no buck noise an EXACTLY the same rpm as scanner...then..after parking it an leaving it off 1st restart ..tach was all over again...
Is the 96 civic one of the ones that the 5 step cluster test can be performed on ?
likely I'll replace cluster ,but it's good to know if this test can be used on 96 an if that maintinence light not coming on when key pushes it in is a factor.
An are either of these that bulb to maintinence light ? 1 has a wire to it direct also
Thanks

 

No. This^ feature is available for 7th generation not 6th or 5th generation Civics.

The 6th generation Civic does not have a maintenance light.

 

So that little maintinence button on this year model is non active or not included..?
-an that key on light on/off test doesnt work on this model then?

Hmm wondering why it performed so differently [an perfect]
after doing it?
Stumped 🤔
but I'll try another cluster.

 

There's a key insertion feature that manually resets (red to green) after an oil change, but it is not a light.

Not sure what you are referring to.

Coincidence