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Z28 Cluster Mod Instructions

16K views 38 replies 12 participants last post by  CapSS92 
#1 ·
Many years ago there was a website (www.9c1.com) that no longer exists that had a great set of instructions of what needs to be modified and how on a Z28 Cluster to work in the B--Body. Think there are also instructions on how to make your own harness. At the time, I thought it would be a good idea to print out ALL of the instructions and Images which show exactly where to modify wire traces even though I bought a ready made Cluster/harness. Glad I did as I have had ZERO luck finding these instructions replicated anywhere on the Net. There were also instructions on how to disassemble the Odometer so you could match your current cluster mileage.

I have been looking for these printouts for a while and thought they were lost along with the website that used to host them. Was starting to 2nd guess myself and my memory and if I even had them to begin with. Welp, I'm happy to say that I just found them over the weekend in all of their Color Glory. Yes, I even printed them out in color. :smile2:

So, for those of you that are interested, I'm going to see about getting it all organized and somehow back into digital format so that I can repost here. Thought there may be some interest in these instructions and just not sure if there are any concerns with these formally being on another site. I will reach out to Admin and make sure this is OK to repost these instructions and if so, give me some time to convert these over into something I can post up and look for more info in this thread.

More to come....I hope. Let me know if there is interest and I'll see what I can do.
 
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#3 ·
#4 ·
Yes, I think your first link to Gerrys page is where I first found all the instructions years ago. The date on the printout is 10/31/2005 so it's been almost 11 years since I printed them out. A lot of links there like to the www.9c1 site and the site itself are dead.

Looking thru what I found I do have the better article for resetting the odometer along with a few others to modify the circuit board. Thought I had one too on building the harness but may have to dig more for that.

Once I get it all gathered up I'll figure out how to post all this stuff. I have a cluster and harness I bought already modified and figured this could be reverse engineered if I ever have to, but having written instructions and pics is so much better.
 
#6 ·
I like going back in time. 0:). A lot of those links look like stuff I've seen in the Impala ss technical archives document. A lot of other links that I completely forgot about. A couple of links to your archive didn't pop up but there are many more there that do and lots of good info in that way back machine.

The 3rd post here has a link to Gerrys thread which is still active and has similar info along with harness pin outs. I have good pictures of the circuit board mods and highlights what each bulb is for. Hopefully with all this info we can gather and post here, will give others the tools they need to do this mod themselves if they gather up the parts. There used to be a member or 2 here that sold these ready to install kits but this may not be an option some want to do or have read of bad stories on these sellers that may or may not be true. In any case, having the info to do this yourself gives us all another option.
 
#7 ·
I found this quote by: 94 impalass

Did the Z cluster and figured I would share some things I figured out and didn't find with a search. First is you don't have to cut the wires on the left stock impala connector and solder them to the z cluster. You can just remove the pins and put them in the correct slots in the z cluster. They both use the same pin type. Basically you have to use a very small jewlers screw driver or the equivalent (I used a staple gun 3/8" staple un bent). Take the connector and look at pin holes. There are four rows of holes. The two center rows are where the cluster pins insert. The outer two rows are what hold the pins in the connector in place. You will see that these outer square holes have a piece of metal against one side. Put the screwdriver in the hole and press toward the metal side until you hear a click. This is the female pin coming free. give the wire a tug and it should come right out. Do the same to the Z28 harness to remove its pin and then slide the impala connector pin into the appropriate slot in the z28 harness. It should click into place. Ta da. Save a heck of a lot of soldering and is a lot cleaner.


94 impalass
I have not seen this method before.
 
#13 ·
Those are good instructions for how to install a Z28 cluster that has already been modified. These instructions Im going to post are how to actually modify the cluster.

Almost a year later and wondering if you've found any time to gather up all the info and get it posted here. I've been thinking a lot lately about doing the Z28 cluster and especially after just having to repair my odometer again.
It's only been a year! 0:). Quite embarrassing really that it has taken me this long and to be honest slipped my mind. I grabbed all the docs tonight and will work on getting these converted to electronic form and then need to figure out how best to post.

Maybe I can add PDF files if they are small enough. I'll try to find some time this week to at least get electronic copies. Once I have those and if I run into problems posting them here, maybe I'll get some suggestions how to share the files.
 
#14 · (Edited)
Sorry this took so long but finally got these papers scanned in. Scanned each in as a JPG so it could be easily linked in photobucket and posted here. I think anyone wanting to do this mod will find these pages invaluable to help with that. They are long removed from the web OR I just couldn't find them anymore and printed these all out many years ago. Thought I had a document on actually building your own harness but can't seem to find that. I'll post it up later if I find it.

Cluster Modification...










How to reset the Odometer.....



 
#15 ·
More info on cluster mod and wiring....

Tach hookup info.....






Wiring info minus page 7 which was blank......











 
#18 ·
Yeah, White Text was not the best color choice for that Tan Background. Looks like eze415 has some better pics he posted that should help. If not, lmk and I'll just type out those sections here.
 
#20 ·
If you want the Gauge to actually function to where it moves with the actual pressure, yes you will need to swap the sensor AND if you don't have a 9C1 car, will also need to remove the resistor in the Oil Pressure Circuit. There is info on this and the 9C1 or the Truck sensor you need to install. The truck sensor reads 0-60 psi and believe the 9C1 reads 0-80 psi which just moves the needle. So at 40 psi the truck gauge puts the needle at about 3/4 on the gauge and about 1/2 way with the 9C1 sensor. Hopefully that makes sense. :wink2:
 
#22 ·
Nice to see the instructions are still useful to everyone and people are still doing this mod. I always get a kick to see the pics and instructions I posted years ago still floating around. And this mod worked great when I installed a Z28 cluster into my 65 Chevelle. :) And I installed an LT1 into it years ago. Guess I haven't strayed too far from my 9c1 days. Although I still hate the Optispark. In the process of replacing it...again.

Alex Melero
 

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#26 ·
I'm still unclear if that resistor exists in ALL Impala SS cars or if it was only used in the 94-95 Impala's which had an actual oil pressure gauge factory instead of the idiot light in the 96 Impala.
94-96 Caprice had a 68 Ohm resistor to fake the gauge reading. (per FSM) It was a "Idiot Gauge".

If the 96 Impala had a idiot light I would guess there was no resistor and you could just change the oil pressure switch to a oil pressure sensor IF you were using a gauge.(cluster change)

I think(?) 9C1 had a pressure sensor, so no resistor.
 
#27 ·
94-96 Caprice had a 68 Ohm resistor to fake the gauge reading. (per FSM) It was a "Idiot Gauge".

If the 96 Impala had a idiot light I would guess there was no resistor and you could just change the oil pressure switch to a oil pressure sensor IF you were using a gauge.(cluster change)

I think(?) 9C1 had a pressure sensor, so no resistor.
Yes, the 96 Impala only has an "idiot light". I'm swapping in a Z28 cluster with an actual oil pressure gauge. I know to get the oil pressure sensor from either a 9C1 or Z28 (same part number).
 
#28 · (Edited)
Ok, i'm trying to figure out what i'm going to do about the tach signal between my 96 Impala and the Z28 cluster. Is it possible to install an MSD 6A box and use the tach output to the factory Z28 cluster? I have an MSD 6A box laying around doing nothing but gathering dust that I could use if it will work, I would just need to buy the MSD 8877 plug n play harness (i'm not into cutting factory wiring and a buddy works for MSD so i'm sure i'll get a discount). It would be cheaper to go this way rather than buying the Dakota Digital SGI-8E tach adapter.
 
#29 ·
In the spring there was a thread about the Impala tach signal.

Someone said if you started with a Caprice PCM file you would get a V8 tach signal.

Someone else posted a picture of Tumer CAT and suggested that you could reprogram the Impala to V8 signal.

I would rather invest in tuning software than MSD parts.
 

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#30 ·
I'm in the middle of making my wring harness adapter and need a question answered, position C2-B04 is a ground in the Impala cluster but there is no pin location given on the Z28 cluster side. In pin location C2-A06 there is a ground that goes to pin location D8 in the Z28 cluster, does this mean that the ground on C2-B04 is not used?
 
#32 ·
Is it just me or do others get confused as well when trying to figure out the cluster schematic? Basically on the dash side (chassis wiring) the wiring connectors are not oriented the same and as such the "drawings" from the FSM would lead you to believe that both connectors started the #1 wire location from the right side of each connector when that is not true if you look at the numbering on the connectors themselves. Basically the FSM would be correct for the left connector starting pin location #A1 on the right top but incorrect for the right connector since it is mounted upside down which now makes the #A1 pin location on the bottom left.
 
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