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1996 Caprice 9c1, 2018 Ram Laramie CC 4x4 EcoDiesel , '03 Ram 3500 Laramie Sport QC 4x4 Cummins
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Discussion Starter · #1 ·
Finally drove my car a today after the Z cluster install. I never could find out why the tach never worked. Driving it today,I noticed the tach gauge move a bit. So I'm thinking I need to take the needle off and reinstall it at idle, what RPM do our cars idle at?
Thanks-Casey
 

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I have a similar issue, one of my cars idles at 750, the other at 875. I checked the 875 for vacuum leaks, etc, & found nothing. My mechanic hooked it up & said he was reading 750 and that my tach was off, so cletus284, your post makes me wonder what else to look at?
 

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My Z cluster is off by about 100 or so, I think that they all are :) But Cletus is correct, doubt it is the needle and if you remove and put it back on your are looking for more trouble that it is worth. PCM is the best place to get the tach signal for the cluster as well.
 

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Agreed pcm for tach signal.
Also if its off just by alittle bit more trouble than its worth to move needle.
If ur tach is only moving a little then its not the needle its either the hookup for it or bad tach itself.
Rev car up to say half throttle if needle has not come up to above 1000 its bad signal or tach not the needle.
 

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Another thing to think about it is a 150mph cluster right? if it is a 110 that could be the problem, the tach is for a V6 I can't remember if you have the resolution for a V6 with the tach resolution from a V8 if it would read double or lower.
 

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1996 Caprice 9c1, 2018 Ram Laramie CC 4x4 EcoDiesel , '03 Ram 3500 Laramie Sport QC 4x4 Cummins
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Discussion Starter · #8 · (Edited)
I'm getting the signal from the PCM. Its the 150 mph cluster and my first thought was a bad tach. The tach doesn't even move but a nut hair. When I received the cluster,the speedo needle was resting on 150 mph and the tach was pegged out also. No telling how many times the shipping box was tossed around and stacked upside down. I moved the cluster around to get the needles back to normal. I thought perhaps the tach needle might have spun some how on the shaft.
I bought the cluster and wiring from a forum member quite a while ago and he did offer me my money back,but I had already had the car torn down and cut up,so I didn't take him up on it.

Is it possible to rebuild the tach itself,or do I need to find another cluster?
Thanks fellas.
Second thought,is there another way to hook the tach up? That way I could find out if its a PCM signal issue or a bad tach.
 

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You can also get the tach signal from the white/black wire of the coil or pin A13 of the RED PCM connector. However I do not personally believe it is your hookup that is bad, assuming you have the wire run to the correct location. I am thinking that its the tachometer driver IC on the cluster. It is not unheard of them to go bad, though I haven't personally heard of it going bad on the Z28 clusters, but anything can happen.

Also if it was the 6 cylinder Camaro cluster the tachometer would read 50% faster. And if it was a '96 Impala SS cluster in a 94-96 Caprice or 94-95 Impala SS it would read twice as fast as GM in their infinite wisdom used a 4 cylinder tachometer for it. - Peter
 

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You can also get the tach signal from the white/black wire of the coil or pin A13 of the RED PCM connector. However I do not personally believe it is your hookup that is bad, assuming you have the wire run to the correct location. I am thinking that its the tachometer driver IC on the cluster. It is not unheard of them to go bad, though I haven't personally heard of it going bad on the Z28 clusters, but anything can happen.

Also if it was the 6 cylinder Camaro cluster the tachometer would read 50% faster. And if it was a '96 Impala SS cluster in a 94-96 Caprice or 94-95 Impala SS it would read twice as fast as GM in their infinite wisdom used a 4 cylinder tachometer for it. - Peter
Thanks Peter I couldn't remember what a V6 resolution tach would look like hooked to a V8.

OP- Peter is right about the connection point, double check it at the PCM to make sure you are in the right pin first then, then go to the coil and see what happens. PCM is the best place to get the information though.
 

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Discussion Starter · #11 · (Edited)
I've already tripled checked the pcm hook up. I'll try the coil. If it still doesn't work,do I just replace the tach itself or is there a specific piece to replace? I don't know crap when it comes to electronics. Anybody have a Z cluster for cheap?
Thanks again guys
 
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