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XJ: Replacement of the Instrument Cluster

Crist Clapper

NAXJA Forum User
Location
Blair County, PA
1987 XJ: Need to replace the instrument-cluster. What do I need to know? Thanks!
 
It isn't hard. You pull the fascia by removing 4 screws. They all face downward. Two are above the cluster, the other two are lower with one of them by the headlight switch.
Once you finish that you can pull that fascia off. There are 6 screws that hold the actual cluster in the dash. Once those are loose, carefully work the cluster forward. There are two electrical connectors. You remove them by pushing in locking tabs on the top and bottom while rocking them to get them out. You can then reach behind and unhook the speedo cable.

Before putting the cluster back, take a pencil eraser and shine up the electrical contacts. Also check the bulbs since they commonly burn out in vehicles that old. Corroded contacts are a very common reason for gauges that don't work right.
 
I suppose we would like some idea of where you are going with this. Are you wanting to plug in another stock cluster or, do you intend to replace all of the gauges with aftermarket? Both have been done and there are some good threads on what is needed.

OK, old_man... you are quicker on the draw than I am. Your post popped in just as I hit post...
 
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I'm fairly sure you will want a cluster from '87-'90 that matches your engine size assuming it will have a tach (4cyl and 6cyl tachs will differ)

once that's accomplished, you will need sending units for the style cluster you are installing-- gauge units for gauges, idiot light sending units for lights. It's plug-n-play after that.
 
Actually, it's possible to swap 4cyl and 6cyl tachs, but it requires some electronics knowledge, and use of something like a signal generator to recalibrate it.
 
Fair question... Un-plug/plug/play. In reading responses... This seems do-a-ble. If so... What/where are good sources for a used replacement? Thanks all! Crist

PS: I'm just getting started with this stock-restoration. So I'll be asking alot of questions... So please be patient with me! :helpme: The is restoration #2... Just finishing up on a 1990 Grand Wagoneer... Didn't get enough with just one! :D :banghead::D


I suppose we would like some idea of where you are going with this. Are you wanting to plug in another stock cluster or, do you intend to replace all of the gauges with aftermarket? Both have been done and there are some good threads on what is needed.

OK, old_man... you are quicker on the draw than I am. Your post popped in just as I hit post...
 
Actually, it's possible to swap 4cyl and 6cyl tachs, but it requires some electronics knowledge, and use of something like a signal generator to recalibrate it.
I did that about 12 years ago.
 
Differs how?
When I tried to put an 89 cluster into my 87, the speedo cable had both a different end and a different method of attachment. It may have been due to the little maintenance clock which runs off the cable. It's been a few years, and I long ago gave away the 89 cluster. All I remember was that it was not quite plug and play, and that I decided to skip the job since the cable was pretty heavily corroded in at the transfer case end, and it seemed too much bother just to get a tach.
 
When I did one of my swaps, one cluster was a push on configuration the other had a screw on retainer. I had a speedo shop local and he simply changed the end on the cable. I could have looked through the cables at the parts store and probably found one. As it turns out, speedo cables are pretty cheap.
 
Actually, it's possible to swap 4cyl and 6cyl tachs, but it requires some electronics knowledge, and use of something like a signal generator to recalibrate it.

all true^^

I'll update/change my response to read "you will want a cluster that matches your engine size assuming you have a tach (and don't want to create a signal modifying generator to alter a 6cyl signal to 4cyl or vice versa) ....

possible? yes
worth the effort? probably not (unless you've got a 4cyl and just have to have a tach before one turns up in the boneyard)




 
I used the local shop myself and a had a custom cable made to adapt the Nissan diesel Tranny in my 85 to the 85 Cherokee dash speedometer. It ran about $85, which I thought was cheep too. It is now one of those endless roundtoit tasks on my endless list, to install the cable, LOL. I still use my butodometer to avoid speeding tickets, LOL.

I bought a digital transducer gadget for the tach on the SD-22 diesel (as there was no way I could think of to adapt it to the dash style gas Techs) to add the tach to mine.

http://www.tinytach.com/tinytach/diesel.php

No doubt there are aftermarket tachs for gassers too.
 
The tach is indeed calibrated for the number of cylinders - on a RENIX rig it is timed off the logic-level ignition pulse signal from the ECU to the ICM, so this kinda makes sense. If you put a 4 cyl cluster in a 6 cyl it'll read 50% more pulses per revolution than it expects, so you'll get tach readings that are 50% too high. If you put a 6 cyl cluster in a 4 cyl it'll read 33% fewer pulses per rev than it expects, so your tach will read 33% low (i.e. ~500rpm at idle, when it's actually running ~750.)

If you wanted to recalibrate one it wouldn't be too hard...

signal generator frequency for a 1000rpm reading, 4cyl: 4 pulses/rev * 1000rev/min / 60sec/min = 66.67Hz
signal generator frequency for a 1000rpm reading, 6cyl: 6 pulses/rev * 1000rev/min / 60sec/min = 100Hz

I *think* I got those numbers right...

As long as you have a decent digitally controlled signal generator and can adjust the knob yourself (iirc it is a small variable resistor on a PCB inside the instrument cluster behind the tach) it should not be too hard to recalibrate.

Some of the speedo cables are still in stock IIRC, but some aren't. Vehicles with cruise control have multiple sections of speedo cable because the transducer for the cruise system is installed in the middle of the cable, somewhere under the dash.
 
It's out! Thanks for all the suggestions and help!
 
I actually converted a 6 cylinder tach to be used on the 4 cylinder about 12 years ago. I calculated the change in one of the resistors and it worked like a champ. I did a writeup but it most likely before the board crashed.
 
If I want to swap out a base no tach cluster to a cluster with tach and all gauges on a 99 is it just a plug and play or do I need to swap water temp sending units, tach?? other???

Thanks for the help, that base cluster drives me crazy.
 
should be plug and play. You might need an oil pressure sending unit but I don't think so, there isn't even a dummy light switch pressure sender in the catalog for a 99.

Your mileage is going to be off unless you have someone with a DRB-III copy the mileage from the ECU into the cluster though.
 
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