dummy light to gauges swap WITH part numbers

I've owned several late model 2.5 and 4.0L XJs and the gauge swaps on the '97+ XJ's are easy...plug and play.

But on my '88 MJ...and being a 4 bngr it seemed uncharted territory.

I asked questions here and on NAXJA and got a few different answers (which I appreciated) but still was not sure IF it would work going form a 4 cyl to the 6 cyl gauge cluster. That's one of the things I liked about the 2 TJ's I owned...they had gauges instread of lights regardless of which engine you had.

I obtained a factory cluster with gauges out of a 1990 XJ sport (4.0L) from the junkyard for about $10. It has the mechanical speedo.

I bought the coolant temp sender from advance auto parts PN: WT761 $17.79

And the oil pressure switch/sender (also from advance) PN: S4185 $33.59 This was looked up for an XJ as I could not find an MJ PN for it.

Both were direct replacements. The oil pressure sender for the 'gauge' is about 3 times the length of the 'light only' sender but that is the only 'visual' difference. It has a single blade connector and the coolant sender is just a post type. I think at some point the oil sender changed to a multi-blade or pronged connector BUT I know up to 1991 this is the correct one...and since the MJw as only built until '92...

All the gauges work just fine (except I think I broke my speedo cable).

So for about $60 I have rid my MJ of the dummy lights!!

Maybe you can answer this for me.....I have an 86 2.5 and the gauge cluster is a large speedo and large fuel gauge. I would like to swap it with one that has a tach. Do you know if that would be a plug and play or no? I'm not sure if the wiring is universal and supports a tach. worst case i'll just get an aftermarket tach but would prefer the factory setup.

Let me know

You should be able to do what I described above. I am not sure if you will need to get the cluster from a certain year range or not (IE '84-86)...but as I said I used a 1990 XJ cluster in an '88 MJ.

You will for sure have to use a 1990 or older cluster.

All the gauges work just fine (except I think I broke my speedo cable).

Did you remember to recalibrate the tachometer from 6-cylinder to 4-cylinder?

Actually I did not touch the tach...and by all appearances it is working perfectly.

Idles around 600 RPM +-. If it starts to give me trouble I will pull the lcuster out and see what I need to do...but I think it's good to go.

Actually I did not touch the tach...and by all appearances it is working perfectly.

 

Idles around 600 RPM +-. If it starts to give me trouble I will pull the lcuster out and see what I need to do...but I think it's good to go.

It shouldn't be. It should be reading (... lemme see, it's a 6-cyl tach w/ a 4-cyl engine so it should be registering ...) two-thirds of the actual RPM. The tach is NOT self-compensating.

What gears do you have, what tranny do you have, what tire size do you have, and what RPMs show on the tach at 60 miles per hour (100 km/hr)?

That may be true on it not being self-compensating. BUT...the engine sounds to be idling exactly how/where it should.

When I rev it up the tach moves appropriately. When driving and shifting (it's an AX-5 the tach moves appropriately. Even the 'up shift' light comes on at the 'right' time in the cluster...and the cluster came from a 4.0L/AW4 XJ. ***this thing has an external slave AX-5...how common is that in an '88...maybe my truck is special! :D

It has a 3.55 rear end with 225-75/15 tires. I have not had it past 30 MPH +- (remember no speedo and I don't have a GPS to verify) or 3rd gear. It's not tagged/insured yet.

All I can say is that it is acting as it should be and appears to work correctly. I've owned several 4 bngrs (2-XJs, 2-MJs, 2-TJs)over the year range of '85-97 so I know the motors fairly well and how they should sound at idle and while driving.

What happened when you did your swap on a 4 bngr like this? Did you have to adjust your tach? What year cluster did you use and what year did it go into? Maybe this exact swap doesn't need to be adjusted?

My friend has a scanner and if he has the 4bngr card (I am guessing it's different than the 4.0L) it will for sure be checked. But again...I see/hear NOTHING telling me it's wrong.

That may be true on it not being self-compensating. BUT...the engine sounds to be idling exactly how/where it should.

 

When I rev it up the tach moves appropriately. When driving and shifting (it's an AX-5 the tach moves appropriately. Even the 'up shift' light comes on at the 'right' time in the cluster...and the cluster came from a 4.0L/AW4 XJ. ***this thing has an external slave AX-5...how common is that in an '88...maybe my truck is special! :D

 

It has a 3.55 rear end with 225-75/15 tires. I have not had it past 30 MPH +- (remember no speedo and I don't have a GPS to verify) or 3rd gear. It's not tagged/insured yet.

 

All I can say is that it is acting as it should be and appears to work correctly. I've owned several 4 bngrs (2-XJs, 2-MJs, 2-TJs)over the year range of '85-97 so I know the motors fairly well and how they should sound at idle and while driving.

 

What happened when you did your swap on a 4 bngr like this? Did you have to adjust your tach? What year cluster did you use and what year did it go into? Maybe this exact swap doesn't need to be adjusted?

 

My friend has a scanner and if he has the 4bngr card (I am guessing it's different than the 4.0L) it will for sure be checked. But again...I see/hear NOTHING telling me it's wrong.

Just because the tachometer is functioning and giving you a reading doesn't mean it's a correct reading. The tachometer counts ignition pulses. With a 4-cylinder engine, two pulses equals one revolution. With a 6-cylinder engine, THREE pulses equals one revolution. So you put a 6-cylinder tach into your 4-cylinder vehicle, and your engine has to go around one-and-a-half revolutions for the tachometer to "see" one revolution. It is showing you two-thirds of your actual engine speed.

I haven't done this swap, but a good friend of mine did, and we DID have to recalibrate his tachometer. There is a potentiometer on the back of the tach, and that's what's used to calibrate it. In the case of my friend, he was updating the appearance of an '84 XJ that already had a tach, so he just hooked them both up and adjusted the new one to match the old one. Since you don't have an old one, you can use an idle tachometer.

As a point of reference, if you ever get a speedometer working or access to a GPS, with 225/75-15 tires and 3.55 gearing, in 4th gear you should get the following readings:

40 MPH = 1723 RPM

50 MPH = 2154 RPM

60 MPH = 2584 RPM

[Edit to add]Wait! You said the tranny is an AX-5? And 3.55 gears? Are you certain? Typically, the 3.55 gears were used with the AX-4, and the AX-5 should have either 4.10s or maybe 3.73s.

I posted a couple more times but they disappeared...?

You say your friend's rig was an '84...with the 1 bbl carb right? That's a fairly different animal from the TBI 4bngr in my '88. (I know you know that I'm just stating the obvious) Wiring is different and that's just a start.

I owned an '85 (XJ of course) myself...was my first ever jeep about 16 years ago. That being said I can see why you had to adjust the tach on that one.

I was not trying to say mine would NOT need it...but that it didn't appear to.

And as of yesterday afternoon it was checked with a scanner and the tach is reading correctly. Maybe they won't all do that but this one is.

Someone put the 3.55 rear end in mine somewhere down the line...with the 5 spd I would for sure have expected the original rear axle to be a 4.10. But I thought the 'fuel miser' AX-4 4 bngrs had 3.31's...not 3.55's?

THe only gauge that isn't functioning (at least for an unkown reason) is the voltage gauge. It won't come past about 9-10V. But the scanner showed the battery as good. So I will have to check out that one. The gauge moves...but is reading low for some reason.

And as of yesterday afternoon it was checked with a scanner and the tach is reading correctly. Maybe they won't all do that but this one is.

If your tach reads correctly, it didn't come out of a 6-cylinder donor vehicle. The tachs prior to 1997 are NOT self-compensating, they are matched to the engines by number of cylinders. The early ones (1984 thru 1986) cannot be adjusted, they have to have a resistor changed on the printed circuit board. The 1987 thru 1996 tachs have the potentiometer and can be adjusted.

Wow...well I guess I'm just an idiot! :D Seeing as I pulled the cluster myself...from a 1990 4.0L XJ...that I also pulled other parts from for my own 1990 4.0L XJ. Maybe those other 2 cylinders were just fake? :hmm: Sorry for being sarcastic but for the love of pete...come on.

Not sure why you can't believe me...the tach works. It came from a 1990 XJ 4.0L. Not sure what else you need in order to believe me but I am not going to actually argue over parts I pulled and worked on myself. :cheers: I am by no means a liar...and have no reason to try and mislead you or anyone else here.

Not sure why you can't believe me...the tach works. It came from a 1990 XJ 4.0L. Not sure what else you need in order to believe me but I am not going to actually argue over parts I pulled and worked on myself. :cheers: I am by no means a liar...and have no reason to try and mislead you or anyone else here.

Then don't. It has been well-documented that the tachometers for the early (up to/through 1996) 4-cylinder and 6-cylinder are different, and have to be recalibrated when changing from one engine to the other. That's not just me saying it -- it has been written up here, and it has been written up on NAXJA. If yours is accurate, I'm happy for you. But it shouldn't be, and I just don't want other people to think theirs will be if they do the same swap.

In a effort to keep things civil here, let me stand up.

The moral of this story is... While it isn't typical to have a 4.0L Tach work correctly in a 2.5L without modifications, in this case it did, be it for unknown reasons. Eagle thank you for pointing that out. Suuperman, thank you for the write up and the part numbers, if you would like I can move this over to the DIY section to keep it easily findable for future references.

Rob L. :cheers:

Just saw this thread and have to chime in. I've calibrated many tachs (as well as the rest of the cluster gauges) and Eagle is right; in order for a 6-cylinder tach to read correct engine RPMs in a 4-cylinder, it must be recalibrated. Some tachs had a potentiometer, and some had to have a resistor changed. Superman, I believe you when you are saying the tach reads correctly; you would quickly see it was reading low if you used a 6-cyl tach uncaled in your 4-cyl. So the only reason I see this tach reading correctly in your application is that someone previously replaced the original 6-cyl tach mistakenly with a donor 4-cyl tach in the cluster you used. It happens. Do you happen to know the tach part number in the cluster you used? It will be printed on the board and I can ID it with the part number. :cheers:

I will try to remember to pull the part number off when I pull the cluster back out to fix the speedo. But on a side note...I have not seen a gauge style cluster in a 4 bngr XJ/MJ...so do they even exist? Even my late model 4 bngrs all had dummy lights. (the XJs)

I searched in a lot of places to figure out what I needed to do as all the swaps I have done in the past were late model ('97+) which are plug and play.

I never said this was and mainly wanted to post part numbers of the senders since no one seemed to know them...or at least I could not find them. All the writeups I found pertained to 6 cyl to 6cyl swaps. No real hard information on the 4 bngr.

Eagle repeatedly pointed out my tach was wrong despite the fact I verfied it with a scanner.

I am admitting this may have been a one time thing and others may not have the same luck so to speak... so Eagle's persistence...? I'm glad he is passionate but I feel discredited myself...partially due to not being a moderator or 'part of the group'.

Move it, delete it...do what you feel is right. That is all I was trying to do.

Sorry for ruffling feathers by trying to help out. Lesson learned. :???: :D

I will try to remember to pull the part number off when I pull the cluster back out to fix the speedo. But on a side note...I have not seen a gauge style cluster in a 4 bngr XJ/MJ...so do they even exist? Even my late model 4 bngrs all had dummy lights. (the XJs):D

From the parts manual:

TACHOMETER

83504458 1 6 Cyl. 1988/89

83504504 1 4 Cyl. 1988/89

83504503 1 Diesel 1988/89

The 1984 4-cyl XJ Wagoneer I once had included leather seats and the full gauge package, with tachometer. My friend's Cherokee, that he updated from the 1984-style cluster to the 1988-style, had full gauges and tach from the factory.

They exist.

Can we stop nit picking each other yet?

Can wan end this? Seriously?

Rob L.