XJwonders

Here's my version of how to swap the "internals" of a full gauge cluster over to the idiot light body (housing).

So here's what happened that led me to do the retrofit.

I got my 88 Comanche little over a year ago and one of the features I didn't liked about it was the fact it had the idiot (3/4 gauge) light cluster. Add insult to the injury; it had the column shift, so it had the PRDNL indicator on the cluster.

I knew I had to get rid of it because when operating the Jeep, I liked to know the exact operating values of the various components to make sure they are within safe parameters. With the 3/4 cluster, it's impossible for me to know. The lights would just turn on when something goes wrong, as like if I'm an idiot.

How do you know if the engine is starting to overheat? No you won't know until it overheated. How am I supposed to stop the Jeep in time if I don't know when it's about to overheat? Stuff like that made me dislike 3/4 gauges.

So I looked around and was able to procure a full gauge cluster from an esteemed member (username intentionally withdrawn to protect him from backlash and embarrassment) here on the forum. I paid and bought the cluster from one of his part-outs (89 XJ with 4.0L). Naturally I was excited when the box showed up at my doorstep.

Except... this happened.

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The member was like "It broke? Oh well, you can fix it".

Naturally I didn't feel like fixing it (I thought about using a soldering iron to melt the plastic together to repair the damage (I have successfully repaired plastics this way in the past)). So I decided to put it on the back burner for now.

Fast forward a year later.

I got fed up with driving with the 3/4 gauges. The oil pressure light kept lighting up every time I went over a bump. **** that ****.

I decided to go ahead with the swap. NOW, I could have done this earlier but there's a perfectly good reason why I kept delaying it...

I always planned on doing the 5 speed swap on the MJ, I figured I would just wait until I actually do the swap and then I ll change out the clusters (remember the PRNDL indicator).

Then I was thinking. Maybe I should just swap the housings with the internals from the full gauge cluster after the 5 speed swap.

Fast forward a year later. I still haven't done the 5 speed swap yet, and I was itching to do a project for the MJ so I decided to go ahead & do it just to kill time. I did a bunch of googling and I saw that most people said both housings were compatible, so I thought I would have an easy time doing it.

BOY they must have obviously assumed that because they obviously have never done the swap themselves.

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The HOUSINGS are NOT the SAME. In fact they are so much different from each other.

Geez. When the things you read on the internet that aren't a proven fact...

So let me back up a bit. I took the cluster out of the MJ, had to unhook the cable for the PRNDL indicator from the steering column. Brought it out to the bench next to the full cluster so I can compare them both

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The printed circuit papers are completely different. So I flipped them over and removed the plexiglass, and the bezels so to expose the actual gauges themselves. The idiot lights are just translucent panels with pictures on it, basically nothing under it except for light bulbs.

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The gauges on other hand were hardwired to the printed circuit papers via screws. (There's no holes for screws on 3/4 housing.

The 3/4 housings had long tubes that rises out against to the panels so to project the light toward a single icon.

The gauges sat down on raised bumps to support it.

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So after some thinking, I decided I ll cut the tubes down and use standoff's/ spacers to hold the gauges at same height on the other housing.

I also laid down the full printed circuit paper on the back of the 3/4 housing so to see where the holes were located, and marked them. I also saw that 3 locations for the light bulb sockets were slightly off too.

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Drilled all the holes with a 3/16 bit.

I had to go out and buy a Dremel for this project. So I used it to cut the long tubes down to less than .740 (the original height of the base where the gauges sat on on the other body).
I also had to trim one of the fins on the 3/4 housing. The speedo had a trip reset button and when you press on it to reset it, naturally the gauge would move backwards slightly. On the full cluster housing, it had a fin that was tall enough to make sure it doesn't move. So I had to measure that height and make sure when I cut the fin down, it was at same height.

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I highlighted the area with a black marker so it's easier for you to see where I cut.


As for the tach, I had to sand the base down to .350 tall so the tach can sit on the correct height.

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I bought some 1/4x1" nylon spacers and cut them all down to .740" I only needed 11 of them. I also got some 3/8x1" nylon spacers & cut two down to .350 and two of .150.

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I dry fit all the gauges on the 3/4 housing with the spacers to make sure they all fit good. And they did. So I took everything off.

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I also reset the mileage on the new speedometer to match my original cluster.

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I also cut out a slot on the bottom of the tach so the PRNDL indicator will show.

I read somewhere that painting the insides white or silvery color would help the light bulbs reflect off & make the backlighting somewhat brighter. So I thought that was a good idea. Unfortunately only white I had was ceramic engine paint so I just said **** it and used it. I think it turned out pretty well.

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I assembled everything back on, plugged in the light sockets (I bought some led lights upgrade kit from One Way Lighting, thanks Jason). It was a good time to install it. I used the black bezel from the MJ 3/4 cluster with the black gauge faces off the XJ cluster along with the plexiglass cause it had the hole for the trip reset button. I think it came out nicely.

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I reinstalled it back on the jeep. I like it. A lot

This swap gave me more than just one upgrade... I now have a functional cluster, a trip meter, a gas gauge with yellow light that goes on when it's low on fuel ( I don't know why the 3/4 cluster doesn't even have that considering they are called "idiot lights" haha.

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So that's that.

craigjacob1

Awesome. I'm really this retrofit isn't more common.
Honestly, who would want a 3.5" fuel indicator with no tachometer?

Ian Walsh

So I am just wondering if this even possible. I have a 96 Cherokee XJ and the gauge cluster went out on my recently like dead. A friend of mine had a gauge cluster could remember what year it was. So the one his is going to give to me is analog and the one that I have is digital and I was curious if there is a way to convert the analog gauge so that it will work in a digital gauge set up.

Sacnasty

I have a 1995 Jeep Cherokee and my just has the idiot lights on mine also and I did some research and found out that the Clusters that have a blue back were made for the Jeeps that were not high output the white back clusters were the ones that were made for high output you could actually take the whole cluster out with the idiot lights and reinstall the one with the alternator gauge gas gauge oil pressure you could take that one and install it in place of the one with the idiot lights. But you also have to change the oil pressure switch and the water temperature switch to match the Guage cluster with those in it. A lot of people didn't know that and they would just swap the instrument clusters out and not change that water temperature switch and oil pressure switch and they wouldn't work you could have just installed the whole new cluster in there. Was there a reason that you did not do that. I may be taking it wrong but it seems to me that you took all the gauges out and put them in your old instrument cluster is that true? anyway just thought I would let you know that... I know it don't matter now but I just seen it and knew that I did the same thing but I just changed the whole instrument cluster whole lot easier.. I know one thing I can take that damn instrument cluster out now in about 5 minutes LOL

XJwonders

I bought the full gauge cluster but it arrived broken. So I had to do this when I took all the gauges into the idiot cluster instead.