Tach related help please - Honda Prelude Forum

Mattsy93vtec · 04-17-2004, 05:13 PM

Hey guys, now I did a search, and found a bunch of threads concerning a crazy tach. One guy said to check my grounds, I checked them and they seem fine, another person said it would be the cluster, but I just dont see why a magnetic driven tach just fry out, didnt' know that was possible.

I read one thread concerning the ICM, but it was in relation to 5th gens. I cant find my damn helms, but, do 4th gens have an ICM too? Where is it located, how do I take apart or how easy is it to take it apart? And is there a procedure to check and make sure (like a helms flowchart?)

I'm going to keep looking for my damn helms, I know its here somewhere, but if anyone knows anything, that would be great, thank you.

- matt

Mattsy93vtec · 04-17-2004, 10:22 PM

4 views eh? wow, lol.

Well, heres an easy question then, where can I get an ICM?

jsmooney · 04-20-2004, 12:12 AM

mine's doing the same, tonight i was going 60 in 4th gear, same speed, it was jumping up past 7 and back down to zero.....mine's done it for about 2 years now, its off and on, im about to disconnect the damned thing. sorry, im not of any help other than letting you know that you are not the only one! if i knew how to fix it i would tell you

Si_g · 04-20-2004, 08:11 AM

i m not sure what you mean by crazy tach, but if its what i think it is,is it that the tach is just jumpin up and down for no reason? if its that, mine did it when i had the key in the iginition and all the intruments on, without the car on, it would just jump up and down from 0 to 4 or 5, and sometimse when i m drivin too. If thats the problem your are havin, i belive its your distriibutor cap thats goin bad. Do you have an ignition upgrade ? ( msd coil plugs and wires ?) i think mine was actin up so i change my coil, and it was still doin it. I went to some mechanics and they told me, theres no way to fix the cap, just ride it til it dies then replace it. I havent changed mine yet, last time it did it was about 7 months ago ( i must add that i slapped the sucker with a wrench a few times lol ) but its been good since then, so i m just ridin it. My friend had that same problem but he went ahead and changed his cap, and hasnt had the problem since.

Mattsy93vtec · 04-20-2004, 08:54 AM

I have a feeling just one of the cables connecting into the ignition module are loose, I'm going to take apart my distributor when I have the time, and the tools, and I will check it.

A good way to pinpoint the problem is to get a Tach tester with a plug that fits into the tach tester plug near the intake plumbing, then you will see if it's a bad signal or simply my guage cluster going to hell...

... I'm going to see how much they are, hopefully not much.

- matt. I'll keep you guys updated.

Si_g · 04-20-2004, 10:29 AM

distributor caps are around 250 or so. I dont even wanna mess with mine, i ll just ride it. It only happened 2wice and that wa over 7 months ago, so its all good for now. I m goin to get a MSD distributor cap to go along with my msd upgrade.

rentien · 04-20-2004, 02:14 PM

one time i had a crazy tach, where i would be driving at 50 and it would read normal, and then drop down to 0 then back up to the normal rpm, somtimes past it, what was happening was the alternator wasn't working, so there was no power and all the electronics starting with the tach and speedometer were failing... i don't think you have the same problem... but if you see the speedometer doing it too, then it might be the alternator not working and you running out of juice

Mattsy93vtec · 04-20-2004, 03:50 PM

Nah I replaced my alternator last year...

jsmooney · 04-20-2004, 04:39 PM

i got a new cap about 40k miles ago, although the distributor could be off of the old h23 depending on what the mechanics did. a new cap is fairly cheap though...i think. lately the car has been laggy in the low end and the tach has been bouncing more than usual.