Corrected title.... Original tachometer cluster in a 1991 K3500. Fuel gauge not working.

[Dajain]

Good Morning Everyone,
I bought this 1991 K3500, 454 V-8 meshed with the 4L80e transmission. It is a tow truck and does not have the original bed on it.

The previous owner definitely knew how to cheat and short repairs in the sloppiest way imaginable. Here are a few things I found, just for laughs and then I'll post my question.

Wiring to the transmission were just twisted together and not protected from shorting out.
Fuel pump assembly was RTV'ed into place.
A fuel pump switch was installed on the dash, when the only thing wrong was the pump relay.
Exhaust was hacked into 6 pieces and left hanging. I think they did this to work on the transmission.
They didn't use butt connectors for any electrical repairs. My collection of wire nuts is building the more I work on it. lol
The fuel fill hose was ran in such a way that the neck was kinked to almost closed and rain could easily get into the tank.

OK, maybe you get the picture.

Now, I'm going thru and "tinkering" with this truck in my spare time and the latest focus is the fuel gauge.
With the RTV mess they left on the fuel tank and pump assembly, I just replaced both. Don't have the patience to try and clean it up.
The new sender is putting out proper ohms, got rid of the fuel pump switch on the dash and got that system working correctly, But the fuel gauge is now showing full grounded condition..

Ok, now, I haven't pulled the cluster out yet but doing some research, this gauge cluster is not from a 1991 truck, but rather a 1994 truck. With the other "repairs" I'm finding, I'm almost scared to look behind the cluster. lol

So, I've looked thru the Chilton and can't find the electrical schematic for the 1994 instrument cluster but do have it for the 1991 but I know the connector is different between the 2.

Simple question... Is the wire for the fuel gauge on the '94 purple like it is on the 1991?

I'm hoping I don't have another tweeker repair behind the cluster. lol
I'll be able to look at it this Sunday and just want to go in with some information I can't find in the Chilton.

 

[89RCLB]

Here's a link to the service manuals, you should be able to get your question answered.

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

Are you sure it's not the 91 cluster? If you haven't pulled the cluster then you won't know for sure until you do.

 

[89RCLB]

Oh, and welcome to the forum

 

[Dajain]

Here's a link to the service manuals, you should be able to get your question answered.

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

Are you sure it's not the 91 cluster? If you haven't pulled the cluster then you won't know for sure until you do.

Did some research and the 1994 Silverado is the only year that has this cluster.

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The '91 should have this cluster in it.

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[89RCLB]

This is for sure the 1991 cluster. Note the location of the gas pump icon, on 92-94 clusters the gas pump icon is located directly under the empty hash marks.

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92-94 cluster

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[89RCLB]

The common cluster for 91's is the second image that you posted. The Tach cluster (your first pic) is really rather rare. Feel lucky you have it! They're really expensive these days if you can find one.

 

[Dajain]

The common cluster for 91's is the second image that you posted. The Tach cluster (your first pic) is really rather rare. Feel lucky you have it! They're really expensive these days if you can find one.

But the only way to tell for sure is to pull the cluster and what pigtail is plugged into the back, Correct?

If it is a rare '91 like you say, it should still use the same pigtail as the moon cluster, correct?
That would mean the wire is purple according to my '91 schematic.

Thanks for the lead to the service manuals too! They will be very helpful.

So, yeah. Not real surprising. it's a '91 with the 4l80e from the factory, now a rare gauge and it was built in Canada. lol

 

[Dajain]

I stand corrected. It does show this cluster in the 1991 service manual. Basic internet searches didn't show this option. That's promising for me.

 

[Drunkcanuk]

Welcome from Alberta Canada.
I have a 91 c1500, it has the Moonies.
You feel free to take your cluster out and send it on up here and I'll send ya mine!!! Lol
They are definitely hard to find, and expensive when you do. I honestly don't mind them.
Hopefully you get your issue figured out.
And feel free to post pics of your rig...we like pictures!!!

 

[someotherguy]

As mentioned the 1991 needle cluster exists. When you pop it out of the dash you'll notice it has the same appearance on the backside as the 1988-1991 "moonie" clusters; in that it is deep and has a metal back plate, and uses the same connector. A 1992-1994 cluster is shallower (less electronics inside) and has an exposed flexi-circuit stuck to the back and an entirely different connector that does not swap with 1988-1991.

There are factory repair manuals linked here on the forum for free download; I'd suggest pulling the 1991 manuals down as the wiring diagrams are going to be a huge help to you. They're in this post in the Engine section: https://www.gmt400.com/threads/88-98-service-manuals.43575/

Richard