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Username Post: 89 Moonies to 91 Needle Gauge swap questions        (Topic#353345)
Guy named Guy 
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Posts: 36
Guy named Guy
Age: 27
Loc: Grand Prairie, TX
Reg: 07-31-13
10-08-18 06:49 AM - Post#2748122    

I have an 89 Silverado with the moonies that I'm not a fan of, and I happen to have (2) 91 model year needle style gauge clusters laying around.
I have done alot of research on how to do the swap and all I can get is, "There are 3 wires that need to be moved on the gauge cluster harness connector in order for the gauges to work properly, and a separate wire must be run for the tach".
Now I'm no fan of wiring either but I think I can handle 3 wires, the problem is I have no idea, nor can I find any information on exactly which wires need to be moved where, or where the tach wire goes.

Any help from anybody who knows would be greatly appreciated as I'm about to take my 12 gauge to the ole moonies.....with them still in the truck just kidding

Also on a side note I am NOT talking about the 92-94 gauges which use a different style connector with a separate DRAC and all that, I'm talking about the one and only (half) year which the needle gauges came with the moonie style connector, 1991.





 
someotherguy 
Senior Moderator
Posts: 28808
someotherguy
Age: 48
Loc: Texas
Reg: 08-01-03
10-08-18 11:19 AM - Post#2748146    
    In response to Guy named Guy

This is for using the 1991 cluster in a 1988-1990 truck:

  • dante1342 Said:
With the plug upside down and facing you so the alignment nubs are towards the top, Row “B” will be the top row and Row “A” will be the bottom row with pin numbers from 1-17 going from left to right.



• Remove the wire in “A10” and re-insert it one pin over to the left “A9”

• Remove the wire in “A11” and re-insert it one pin over to the left into “A10” which is the wire you previously moved.

• Remove the wire from “B15” and put into the hole which should be empty for “B11”

• Insert the wire you ran from your coil Tach lead into “B15”


The coil lead he's referring to for the tach is the white "spare" connector you'll find currently not connected, just taped back to the harness, near the coil.

And unless your needle cluster came out of a truck that coincidentally had the same original axle ratio and tire size as your truck, you'll need to re-calibrate the speedometer, too. I've got a write-up on that in the sticky FAQ post at the top of this forum.

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
Guy named Guy 
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Posts: 36
Guy named Guy
Age: 27
Loc: Grand Prairie, TX
Reg: 07-31-13
10-08-18 01:45 PM - Post#2748161    
    In response to someotherguy

Thank you much someotherguy, that is exactly the information I was looking for!

About the axle ratio, My truck is an 89 Heavy half 4x4 with a 700r4 transmission and 3.73s (according to RPO code GT4) also G80

One of the clusters came out of a truck I used to own a long time ago.
It was a 91 silverado 1500 extended cab and it had either 3.73's like my truck or maybe 3.42's

The other one I have came from the junkyard out of a 3/4 ton 5 speed truck - not sure of the rear axle ratio.

My questions are:
If the cluster is calibrated for 3.42's, how inaccurate would it be in my truck with 3.73's
and
For the Tach I just run a single wire connected to the coil connecter taped to the harness - through the firewall to the B15 terminal on the cluster harness connector correct?




Edited by Guy named Guy on 10-08-18 01:47 PM. Reason for edit: No reason given.

 
bowtie44s 
Valued Contributor
Posts: 4093
bowtie44s
Age: 35
Loc: wv
Reg: 08-29-12
10-08-18 04:08 PM - Post#2748174    
    In response to Guy named Guy

Go ahead and solder in the DIP switches so you can calibrate it. It's easy and the link in the FAQ will walk you through it. Richard likes the vacuum desolder tool, I like the braid. It's personal preference.

You will need a terminal to run to your tach. I used the one for my seat belt light. You can buy a terminal release tool, but I used the small screwdriver bit on a Leatherman multitool. If you have to pull very hard, it's not released. They should slide right out once you get them released.

Jeff

'88 Chevy K3500, aluminum head roller cam 511in³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
Guy named Guy 
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Posts: 36
Guy named Guy
Age: 27
Loc: Grand Prairie, TX
Reg: 07-31-13
10-11-18 12:21 AM - Post#2748398    
    In response to bowtie44s

I can't seem to get the Cluster connector out of the dash and it seems that alot of people have cut their dash to get it out. Is there any way to get it out other than cutting or breaking it?
And if it needs to be broken how are you guys mounting it after that, just let it hang and plug it in or what?



Edited by Guy named Guy on 10-11-18 12:35 AM. Reason for edit: No reason given.

 
Guy named Guy 
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Posts: 36
Guy named Guy
Age: 27
Loc: Grand Prairie, TX
Reg: 07-31-13
10-11-18 03:42 AM - Post#2748408    
    In response to Guy named Guy

Update - After further research I went ahead and cut a notch in the dash so that I could get the connector out far enough to reach the individual wires but I now have a new problem. For the life of me I can't get any of the terminals to release using a variety of tiny flat heads and picks.
I need to get me a terminal release tool but the terminals are so small it's hard to see which type will be needed and this is the first time ever that I've had trouble getting terminals to release.
Before I mangle them up too much do you guys have any more details on it that might be helpful?

Thanks



 
bowtie44s 
Valued Contributor
Posts: 4093
bowtie44s
Age: 35
Loc: wv
Reg: 08-29-12
10-12-18 12:52 PM - Post#2748520    
    In response to Guy named Guy

The screwdriver on my leatherman measures .070. You need something close to that. There are 2 holes, a big one and a smaller square one if I remember correctly. The small one is the one you need to put something in. They release pretty easy when you get something the right size.

Jeff

'88 Chevy K3500, aluminum head roller cam 511in³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
Guy named Guy 
Poster
Posts: 36
Guy named Guy
Age: 27
Loc: Grand Prairie, TX
Reg: 07-31-13
10-12-18 06:56 PM - Post#2748542    
    In response to bowtie44s

Thanks Bowtie
I guess what I was using was a little to big in the first place, so I used the smallest flathead I had and got them to pop out.
The problem was I couldn't figure which hole the release tab was in. I chewed up one of the holes just a little, and didn't want to continue until I knew for sure which hole it was in. Thanks Again.

Anyway I insalled the 91 needle gauges today without the tach just for a test run to see if the speedo was even remotely accurate, and coincidentally it was spot on according to gps so I guess the truck I pulled it from at the junkyard must have had the same tire size and rear end ratio after all. However it came out of a 5-speed truck and has no PRND21 so I'll probably end up going with the other one which came from a truck I had with smaller tires and probably a 3.42 rear end. So I'll end up doing the whole dip switch thing soon and I'll let you guys know how it goes.
Thanks again someotherguy and bowtie44's




 
someotherguy 
Senior Moderator
Posts: 28808
someotherguy
Age: 48
Loc: Texas
Reg: 08-01-03
10-13-18 03:08 AM - Post#2748552    
    In response to Guy named Guy

You can move the gear indicator piece of the cluster over, no biggie. Easy work

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
Guy named Guy 
Poster
Posts: 36
Guy named Guy
Age: 27
Loc: Grand Prairie, TX
Reg: 07-31-13
10-13-18 04:05 AM - Post#2748553    
    In response to someotherguy

You know something I never even checked man, it was no biggie since I have one with the gear indicator anyway. But now I'll just leave that cluster in the truck. Thanks man very helpful.



 
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