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87 Choo Choo
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Did GM in it's infinite wisdom use two different printed circuit boards for 87 gauges whether a tach was included or not?

Yesterday I received the gauge cluster I snagged on evil bay. Broke it all down and cleaned it last night. The circuit board is in fair shape, but not great. I was hoping that I would be able to use my original, which I'm sure is totally unmolested or damaged.
 

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Did GM in it's infinite wisdom use two different printed circuit boards for 87 gauges whether a tach was included or not?
Hmmmm.... GM and infinite wisdom used in the same sentence? I think that's an oximoron.

There are two different gauge clusters and both use a different circut board. One cluster is for the idiot light dash and the other is for the gauges and tach. You can't use the idiot light cluster circut board with the gauges and tach cluster.

I'll look up the cluster and circut board part numbers. I'm pretty certain that they are no longer available from GM. When the circut boards were available they were in the $200 range. I've seen some used circut boards on evil-bay for about $100.

I may have a good used one in the garage. I'll check tonight.

:mrgreen:
 

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87 Choo Choo
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Discussion Starter #3
Ernie;

I think you just answered my question. I currently have gauges, just no tach. I bought the Monte SS cluster for the tach and the SS guage bezel to match my radio bezel and dash insert. My original circuit board should work (yea!)

As an added bonus the donor cluster also had the trip meter reset knob I've searched high and low for. Pretty silly to get excited over a fidy cent part isn't it! :p
 

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Printed Circuit Board

When adding a tac to your cluster I beleive you might need the tac filter also. Its located under the hood on the fire wall behind the dist. Maybe another member knows more and can explain ,Good luck and enjoy
 

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Hey Ernie,

Just thinking here but... if the original cluster had no Tach then did the harness have the lead for the tach? In other words that harness has no wire going to the distributor, does it? So wouldn't you have to add that wire to the harness. Its not just going to plug in and be that easy will it.

Don't the gages use a different sending units than the lights version of the cluster and someone mentioned a Filter. My manual for the 80 shows a 10 ohm wire in parallel, if I remember correctly, with the Oil pressure gage or was it the Tach? It not a filter it is an offset or something like that to set a bias for the gage to operate correctly. Or.... Was I hallucinating from too damn much smoke?
 

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87 Choo Choo
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Discussion Starter #7
There were three small posts on the back of the tach that went through the donor circuit board and attached with small retainer nuts. There was a fourth connection point that I assume the filter attaches to. Since I already had gauges, although no tach, I believe that portion of the circuit board must exsit on my original gauges cluster. Just not currently hooked up to anything.

When searching for info on the circuit boards, I only found two listed, one for idiot light the other for gauges...I think I'm ok.
 

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You will be missing the white wire to the distributer in the printed circuit board connector. I usually just attach the wire with a ring terminal and nut. Anyway, here's something I wrote up a while back...maybe I should post it somewhere eh? Peter, take some photos while you do the mod and we'll make up an article with these pics.
Also, the filter is optional. It's just for radio interferance and can make your tach a little bouncy if you don't have one....
PS, you may also use an old style points condensor as a filter.

Gauges
 

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I have 87 elky, I am in the process of trying to switch from lights to gauges. I was looking at the prints of circuit board and noticed that the one i have has only one connector with 18 numbers on it and the ones on your diagram has 2 connectors. I am lost , and also with the cluster that i bought on evil bay it had no pod, so now i am looking for another pod that will work with gauges.
 

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ElkyPete said:
Hey Ernie, Just thinking here but... if the original cluster had no Tach then did the harness have the lead for the tach? In other words that harness has no wire going to the distributor, does it? So wouldn't you have to add that wire to the harness. Its not just going to plug in and be that easy will it.
It's as simple as plug and play.

When I installed a tachometer in my 87 El Camino the white wire for the tach signal was already in the dash harness. My original cluster had gauges but no tach. The white wire led to a connector under the dash just above the ALDL. I just mounted the tach filter on the firewall, hooked one end to the distributor pulse and the other end plugged in under the dash.



:mrgreen:
 

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87ElCamino said:
Big Tex said:
...the one i have has only one connector with 18 numbers on it...
This is the 18 pin connector he's talking about:



:mrgreen:
Hmmm... What year is that from?
 

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acauth1 said:
Hmmm... What year is that from?
I think I got this one out of an 85 MCSS. I've got about five or six more in the garage and they're all the same. Over the last year or so I've sold several on ebay and they were the same. The one in my 87 is the same too.

:mrgreen:
 
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