tl;dr: Can the tachometer be dead from the ICM, while the car still works and drives fine?

Just picked up a 94 civic as a daily for fairly cheap and have been working to try and fix the little problems here and there.

First was that the tach/fuel/temp on the gauge was not working. Thinking that the gauge was bad, I went and picked up another and voila, the fuel and temp started working. Tach, nada.

I've been doing research and know that the blue wire from the distributor goes to the driver side firewall and then through and to the ECU / cluster. Great. Checked continuity from distributor plug to firewall, and firewall to cluster, all checked out. Checked AC voltage on the blue wire and I'm getting nothing, though resistance changes with the RPMs.

At this point my thought is that it *might* be the ICM, as when I took the distributor cap off there was a good bit of oil in there, which means the seals are out, and the wires which are BLK/YEL and WHT/BLU are pretty much discolored beyond recognition. However...I'm not having any issues starting, cranking, shutoffs, etc.

Can the tachometer be dead from the ICM, while the car still works and drives fine?

 

well, if youve got oil in the distributor, its quite likely that the sheath on the wires to the sensors in the distributors body has been softened by the oil and also quite likely dissolved (happened to me) and is causing a short/dead sensor. <---personal experience

If the sensor pickups cant relay a signal, yeah, I'd imagine what you're seeing can happen...tho not necessarily a dead ICM, just a dead signal for the tach.

 

My 98 LX had a bad tach. I replaced the little circuit board that's bolted directly to the back of the tach and it works perfectly now. The little board i'm talking about requires removal of the tach from the cluster to access it.

My tach needle was stuck on the wrong side of the stopper.

I pulled the cluster apart, rotated the needle counter clockwise to put it on the correct side of the stopper.

The minute I turned my key on it started slowly climbing up until it was again buried on the wrong side of the pin.

 

That would be a possibility, but I got another cluster thinking that might have been the problem as well, with the same end result, so I am presuming that the cluster itself is not the problem at this point.

 

Makes sense. It's funny that everything else works except the tach (and the auto transmission shifting kind of hard, but that's another issue entirely), even though the whole distributor has been compromised. I'm planning on grabbing one from a junk yard this weekend to swap out and test. Fingers crossed it fixes the issue.

 

Yeah the chances of two clusters having the exact same symptoms is extremely rare.

FWIW not only was the circuit board on my tach bad, my fuel gauge was bad also.

Today a CRV cluster arrived in my mail. Installed it and all is happy!

 

For the eg I think you can tap into a blue wire that is sitting by the driver side shock tower.

 

Yep, I tried that as well, same result, which made me believe even more that it was explicitly something with the distributor.

 

So, an update for anybody that is interested, I fixed the problem. I grabbed a new distributor that was from a slightly older Accord that looked the exact same, however was obviously in better condition. When I got it home and tried it out, the car wouldn't even start.

Taking it apart, I found that the rotor looked completely different, but the actual components seemed to be the same (just brand new looking). So, what I wound up doing was pulling off the rotor and pulling out the ICM from the new distributor, swapping it with the ICM from the old, and the connecting black/yellow wire. Threw it all back together, tossed it in, started it up, and voila, tachometer.

Now I just have to figure out why there is such a kick when I switch into reverse.