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.

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:

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

I currently have gauges, just no tach.
Then the circut board you currently have will work in the new cluster.

:mrgreen:

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

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?

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 (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&category=40017&item=2442258392#ebayphotohosting) 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.

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 (http://elcaminocentral.com/files/gauges/)

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.

I checked again and it has only 1 connector. If i could figure out how to post a picture i would show what i got.

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.

http://elcaminocentral.com/users/elcamino/tach_con.jpg

:mrgreen:

Here is the tachometer schematic.

http://elcaminocentral.com/users/elcamino/pics/tach_schem.jpg

:mrgreen:

...the one i have has only one connector with 18 numbers on it...

This is the 18 pin connector he's talking about:

http://elcaminocentral.com/users/elcamino/pics/18_pin_con.jpg

:mrgreen:

...the one i have has only one connector with 18 numbers on it...

This is the 18 pin connector he's talking about:

http://elcaminocentral.com/users/elcamino/pics/18_pin_con.jpg

:mrgreen:

Hmmm... What year is that from?

Hey Ernie - What the hell is an "ALDL" on your diagram? If I don't have one, should I buy one? What does it do anyway? DUH.

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:

Hey Ernie - What the hell is an "ALDL" on your diagram? DUH.
Assembly Line Diagnostic Link. I don't think you have one John. Your Elky doesn't have the ECM anymore.

:mrgreen:

Good Golly, Miss Molly...we're gonna have to archive this one!

Was wondering if you had a schematic for the eighteen pin connector, i need that and a pod too. Thanks for any help.

Good Golly, Miss Molly...we're gonna have to archive this one!

See what you started Peter!

:mrgreen:

I'll look up the cluster and circut board part numbers.
Gauge housing - 25044869
Gauge circuit board - 25016702

Idiot light housing - 25044870
Idiot light circuit board - 25016703

The circuit board number is on the back center of the circuit board. The housing number is on the front of the housing underneath the gauges/idiot lights.

:mrgreen:

Was wondering if you had a schematic for the eighteen pin connector.
There is no one schematic for the 18 pin connector. However, I've scanned the 87 schematics of both the indicator (idiot light) cluster and the gauge cluster so you can see the differences.

http://elcaminocentral.com/users/elcamino/schematics/

I've tried to compile the connections for the 87 gauges cluster into this:

1.
2. Oil pressure sender (tan)
3. Coolant temperature sender (dk gre)
4. Fuel gauge sender (pnk)
5. Instrument panel lights (gry)
6. LH turn indicator (lt blu)
7. No connection
8. RH turn indicator (blu)
9. Ground (blk)
10. SES indicator (VIN H or G yel)(VIN Z brn/wht)
11. 12V from gauges fuse (pnk/blk)
12. High beam indicator (lt gre)
13. Fasten belts indicator (yel)
14.
15. Brake warning (tan/wht)
16. 12V from gauges fuse (pnk/blk)
17. Tachometer signal (wht)
18. 12V for Clock (not used)

:mrgreen:

Thanks for all the help from everyone. I would be lost without yall. Now i am waiting on my dash pod and need to get sender units.

Thanks - this is exacyly what I was looking for. I'll let you know how it turns out.

Thanks - this is exacyly what I was looking for. I'll let you know how it turns out.

Please take copious notes and lots of pictures if you can. I have all the parts but have yet to start the install.

Thanks for the picture on the connection. That is exactly what I was looking for. I should be having fun this week end with a working tach.

Hello, I'm an El Camino rookie who just joined the site yesterday. After having read this thread, I might be a little more confused than before I started to read it. I have an'87 Elco that had guages but it had the delete plate in place of the tach. I wanted to put a tach so I found a guy parting out an "86 Monte Carlo SS. I bought his guage cluster, pod, circuitboard (for tach guage cluster) and filter. However when I installed the Monte's tach into my existing cluster and circuitboard, nothing happened. Looks good but I wish it would work. I mean after all that's why I went through all this, right? Anyway,what am I doing wrong? Is there an additional fuse that I have to install, do I have to swap the '86 Monte's tach circuit board into my '87 as well?

Oh and by the way, on the end of the filter wire that plugged into the '86 Monte's dist. cap, where does that now go because the cap looks different. If I'm not mistaken there appears to be two leads with two wires each that go into this thing that is not part of the cap but positioned just in front of it. Which wire do I tap into of these 4? Should I just splice the wire into it because the connector that would normally go into the cap on the '86 doesn't exist on my '87. I read it's the pulse side (-) but what color wire is that on '87. Any help anyone on this forum can give me with this would be greatly appreciated. Sorry for the long-winded post, but I just wanted to be as clear as possible. Thanks, Benj

If you don't have the filter plugged into the distributor signal the tachometer will never work. You should have mounted the small circuit board from the Monte cluster onto the back of your existing gauge pod. The tach gets it's 12V through it. There is no extra fuse. It's just plug and play. There should be a single short wire sticking out of the underhood harness near the distributor that the tach filter connector will plug right into. I don't remember the wire color, and my Elky is at the body shop so I can't look to check it out.

Hey Ernie, Thanks for getting back to me. So, I can't use the circuitboard that the '87 El Camino came with. I have to actually change it over to the the circuitboard that the '86 SS Monte Carlo pod came with. Then they are actually different!. Okay I'm glad you clarified that for me because I was ready to sell the circuitboard and the guages, speedo, pod etc. that were left over. I just thought I needed the tach and nothing else.

On the topic of my tach wire. I also got the filter from the Monte SS but my firewall needs to drilled to accept the grommet. Off hand do you know what size the hole for the rubber grommet should be?

Oh and the loose wire coming out of the firewall near the dist to connect the filter, would that be there if my car neither came with the filter or tach? I already saw the connector under the dash, in the harness, for the filter to guage hook-up. That was pretty exciting because I was worried that the wire would not be there, because my car didn't come with the tach. Thanks for guiding me through all this Ernie. Benj

No, No, No.

They are not different. If your Elky dash pod already has the gauges, then all you need to add to it is the small circuit board that the tachometer plugs into. It's a light blue color plastic that has the terminals that the tachometer plugs into.

http://elcaminocentral.com/users/elcamino/pics/tach_board87.jpg

The underhood connection for the tachometer filter will be there even if the Elky didn't originally come with a tachometer. At least it was in mine. :-D

I don't remember what size the hole was but if you already have the grommet, can't you just measure it?

Ernie thanks for the pic. That cleared up a lot of things for me. Okay the blue plastic is what what everyone is referring to the circuitboard. Sorry for the confusion. Yes, I did swap that out the first time around otherwise I wouldn't have been able to connect the tach on the backside. What I thought everyone was referring to when they said circuitboard was the clear plasticky flat copper circuit that connected all the guages together. I thought there might have been two different types, tach/no tach. Okay that's settled, now I am i step away from connecting the tach. I need to identify which wire is the negative pulse so that I can connect the filter and complete the circuit. Your car is in storage right? Anyone else out there with an 87 who might knowj the color and exact location of this wire? Thanks Ben

I thought there might have been two different types, tach/no tach.
There are two types of gauge pods. One for gauges and one for idiot lights. Read the second post in this thread.

Ernie, It's me again. I noticed you happen to have a lot of pictures related to this topic. Would you happen to have one for under the hood that shows the filter connection hookup? I'm having a slightly difficult time locating this highly elusive wire and that is pretty much the only thing holding me up from having a functional tach. Thanks, Benjam

I can't help you there. My 86 MCSS has the big distributor so that doesn't help. My 87 Elky is in the body shop so I can't get a picture of the connection. Maybe someone else here with an 87 and a tachometer will be nice enough to take a picture for you.