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AW4 swap early to late

spctrbytz

NAXJA Forum User
Location
Abilene, TX
I am looking at buying a 2000 2WD XJ with a bad transmission, and own a wrecked '87 4x4 with a good AW4/NP231. I have read several posts here where people are installing late transmissions in early vehicles, what about the other way around?

Thanks

Tony
 
Splines are different, but if you keep the tcase that should be fine. Later model tcases use a different ouput shaft so the rear drive shaft may be problematic. The late model tcases use a different spedo connect.

You will need to swap the speed sensor in the tranny IIRC and maybe the neutral safety switch.
 
Won't work, without a lot of work.

A 98 and later XJ AW4 has both an input and an output speed sensor, a 97 or earlier only has an output speed sensor and it's different. You can swap the output speed sensor over but you still won't have an input speed sensor.

You *might* be able to get away with it if you get a 97 TCU (and leave the original 87 output speed sensor on the transmission when you install it) but I have not tested this yet so don't try it unless you like being a guinea pig.

If you can find an AW4, NP231, and rear driveshaft (since 2wd vs 4wd rear driveshafts are different lengths) from a 98 or later it is bolt-in. Then you are only a dana 30, shift linkage/handle, and front driveshaft from having 4x4, also.
 
Thanks for the info.

Upon taking delivery of the XJ, I suspect that it has a faulty ignition switch that is not sending power to all the places that ought to have power. An AW4 that is being told either crazy things or nothing by the TCU deserves the benefit of the doubt before yanking.

The new switch should arrive tomorrow, will see what happens then.
 
Thanks for the info.

Upon taking delivery of the XJ, I suspect that it has a faulty ignition switch that is not sending power to all the places that ought to have power. An AW4 that is being told either crazy things or nothing by the TCU deserves the benefit of the doubt before yanking.

The new switch should arrive tomorrow, will see what happens then.

Really curious about what symptoms you have.
 
Symptoms that I have noted so far, but have not yet had time to investigate:

CEL lit

Airbag light lit

No A/C compressor clutch engagement

No power windows from any switch

Transmission will not shift out of 1st gear until 4500 RPM

PO had rigged a button underhood to engage the starter, may have to undo his handiwork after ignition switch replacement.


I don't know if the no-crank is caused by a bad ignition switch or maybe no signal from the NSS. With some but not all of the power accessories dead, it seemed like a cheap thing to throw at it. I will start a new thread if this ends up being an electrical quest rather than a simple case of a bad tranny.
 
Symptoms that I have noted so far, but have not yet had time to investigate:

CEL lit

Airbag light lit

No A/C compressor clutch engagement

No power windows from any switch

Transmission will not shift out of 1st gear until 4500 RPM

PO had rigged a button underhood to engage the starter, may have to undo his handiwork after ignition switch replacement.


I don't know if the no-crank is caused by a bad ignition switch or maybe no signal from the NSS. With some but not all of the power accessories dead, it seemed like a cheap thing to throw at it. I will start a new thread if this ends up being an electrical quest rather than a simple case of a bad tranny.

You need to get the codes read and post up the actual numbers.

The shifting to 2nd at 4000-4500 rpm is normal. You can usually improve shifting overall by adjusting the throttle body pressure cable.

The NSS is such a common problem with these XJs. They are expensive, better to try and clean, lube, and adjust it yourself.
 
Got antsy last night and hooked up a scanner to it.

Results (can't remember the numbers offhand)

Engine temp sensor dead
TPS dead
Gear selector stuck in park or gear (guessing gear for no crank)

Advanced codes show a generic transmission failure.

Best: I look under the thing and find this - seems like the XJ is trying to turn down the diameter of the driveshaft using some of the transmission wiring. When I can get greasy I'll dive under there and see what can be done about it - I lifted the wire off the driveshaft and see every wire of that bundle (3 total) showing an inch of very shiny copper.

lathe.jpg
 
Looks like it succeeded... a little... took some rust off at least!

Not sure which wire that is by location. Looks like an O2 sensor or the VSS (vehicle speed sensor) harness maybe?

And wow, previous owner should have learned to keep his fingers out of the electronics and turn it over to a pro, sounds like a real "handyman."
 
Yeah, kinda puts a whole new meaning on "Monkey Wrench", changes it from a noun to a verb.
 
Update:

Torn up wiring went to the rear O2 sensor, not tranny related. Took the gear position switch off the passenger side and gave it a thorough cleaning involving Gumout, a brass-bristled brush, and dielectric grease.

Installed a new TPS and coolant temperature sensor, cleared DTCs. Cranked it up (properly with the key and removed the rigged-up button) and let it run a few minutes. Took it out for a short road test, and found the transmission to be going through all the gears in a normal manner.


HOWEVER a new problem has emerged. The temp spiked up pretty quick and I skedaddled back to the house. It had lost a bunch of coolant. I removed the radiator cap and disconnected the upper radiator hose from the thermostat housing, then slowly added hot tap water until it flowed from the thermostat housing. Then I reconnected the upper radiator hose and cranked the engine. It is merrily burping a little $&#*(#$!&$*(! EXHAUST from the open radiator cap as it idles.

At least the tranny is good.... I need a nap.
 
Sounds like the 0331 cracked head between cylinders 3 and 4. Sorry man.
 
No worries... I traded (even) a 1995 Mustang V6 with a bad tranny for this, and the body and interior are near-perfect. It'll turn out to be a nice Jeep.

With the selection of tools I own, I would actually prefer to change the head than the tranny.
 
I think 03+ 4.0 heads with the TUPY foundry name on them are the "fixed" heads.
 
Won't work, without a lot of work.

A 98 and later XJ AW4 has both an input and an output speed sensor, a 97 or earlier only has an output speed sensor and it's different. You can swap the output speed sensor over but you still won't have an input speed sensor.

You *might* be able to get away with it if you get a 97 TCU (and leave the original 87 output speed sensor on the transmission when you install it) but I have not tested this yet so don't try it unless you like being a guinea pig.

If you can find an AW4, NP231, and rear driveshaft (since 2wd vs 4wd rear driveshafts are different lengths) from a 98 or later it is bolt-in. Then you are only a dana 30, shift linkage/handle, and front driveshaft from having 4x4, also.


Sorry to hijack the thread but could I get a direction on more info regarding this?
I just finished putting a '99 engine and AW4 tranny into my '97 XJ, the old tranny had 5 wires coming from it that plug into the main harness (1 for each of the three solenoids, and two for the speedo?), whereas the new tranny has 7 wires.

Had to cut off the old multi-socket and crimp the wires onto it to plug it in, though I still have the spare two wires not going anywhere, and of course the tranny doesn't shift properly at the moment (it'll start off in 1st gear but after half a second or so its shifting up into overdrive immediately).

Is my solution to replace the entire wiring harness in the '97 with that of the '99?
My granddad (mechanic for over 50 years) is visiting from the UK and has been helping me with the engine/tranny swap the whole time. Would like to find some answers on this before he flies back on Sunday :)
 
Put the 97 sensors onto the 99 transmssion.

With the switch to two sensors in 1998, the rear speed sensor changed from 1 pulse/rev to 4 pulses/rev. So, you need to swap the rear sensor rotor and sensor if putting a 98+ AW4 into an older Cherokee that expects 1 pulse/rev. The input sensor is simply not hooked up.

91-96

0.75:1 OD ratio
23 spline output shaft
Electrical connections - early model 6 pin wire connector
One transmission speed sensor (output only) 6 pin wire connector

1997-

0.75:1 OD ratio
23 spline output shaft
Electrical connections - late model 8 pin wire connector
One transmission speed sensor (output only)

98-01

0.75:1 OD ratio
23 spline output shaft
Electrical connections late model 8 pin wire connector
Two transmission speed sensors (input and output)
 
This what I have been looking for did a swap myself from 99 transmission 2wheeldrive to a later model 4x4 . My 99 has the 7 plug and the new 4x4 transmission has 5 plug . So I just need to swap the back speed sensor ? Going do that in the morning
 
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