Everything you ever wanted to know about the AW4

[kastein]

If I knew anything significant about the standards used in XJs, believe me I'd write one up... but I don't

Just know that there was a BA5, BA10, AX4, AX5, AX15 (internal and external, not sure on switchover), and NV3550.

Send me an NV3550 to look at and I will tell you everything I possibly can

[Gaidge]

Originally Posted by kastein

If I knew anything significant about the standards used in XJs, believe me I'd write one up... but I don't

Just know that there was a BA5, BA10, AX4, AX5, AX15 (internal and external, not sure on switchover), and NV3550.

Send me an NV3550 to look at and I will tell you everything I possibly can

If I had the money and space, I'd buy one at the JY and pull it apart and learn but alas, a garage has eluded me for the past 5 years...damn you housing market!

[ehall]

Good info Ken, thanks for getting this started. Here's some more data.

1987-1991 had a Power-Comfort switch that caused the TCU to change between two different shift tables. 1992 and later models did not have the switch, and used the Power mode by default.

On my 1991 model, the "Power" mode uses the following shift table:

1st
2nd
3rd
3rd w/ torque lockup
Overdrive (no lockup)

When the Comfort mode is enabled, the table changes slightly, and also occur at lower RPM to produce a smoother shift

1st
2nd
3rd
3rd w/ torque lockup
Overdrive w/ torque lockup

The Power-Comfort switch provides a ground signal to the TCU. Later models still had the pin on the TCU but did not have an exposed switch. I don't know when the last year TCU had the pin.

Almost every year has a different part number for the TCU, which indicates that there were a lot of changes. However the physical connectors did not change and the transmission harness is mostly isolated from the ECU, so they should be mostly interchangeable within the various generations. It would be interesting to know what changes were made.

[DieselSJ]

Originally Posted by ehall

Good info Ken, thanks for getting this started. Here's some more data.

1987-1991 had a Power-Comfort switch that caused the TCU to change between two different shift tables. 1992 and later models did not have the switch, and used the Power mode by default.

On my 1991 model, the "Power" mode uses the following shift table:

1st
2nd
3rd
3rd w/ torque lockup
Overdrive (no lockup)

When the Comfort mode is enabled, the table changes slightly, and also occur at lower RPM to produce a smoother shift

1st
2nd
3rd
3rd w/ torque lockup
Overdrive w/ torque lockup

Are you sure about the OD with no lockup in power mode? That would generate A LOT of heat. Plus my '91 locks the TC in OD in power mode.

[OverlandZJ]

Originally Posted by kastein

As far as I can tell all 5.2L 93 ZJs got the 42RE though.

The earlier (93-95) 5.2 used the 46RH and later (96-98) used the 46RE iirc.

The 42RE was the only trans used behind the 4.0L ZJ after the 93.5 date when the AW4 was discontinued.

[Slip Kid]

Originally Posted by DieselSJ

Are you sure about the OD with no lockup in power mode? That would generate A LOT of heat. Plus my '91 locks the TC in OD in power mode.

My 87 does as well. Just changes the shift points.

[ehall]

I think the Power mode does go into Overdrive w/ TC lockup afterwards and I probably just left off the last shift in my previous notes. I used a Snap-On scanner to watch the differences but I didn't make very good notes.

[ehall]

Originally Posted by ehall

On my 1991 model, the "Power" mode uses the following shift table:

1st
2nd
3rd
3rd w/ torque lockup
Overdrive (no lockup)

Yeah I transcribed wrong. Should be

1st
2nd
3rd
Overdrive (no lockup)
Overdrive (with lockup)

[Norsk62]

Are you sure about the spline count on the input shafts on the T-case? My stock 93 AW4 w/NP231 has a 21 spline shaft? You claim it should be a 23 spline?

[kastein]

That simply isn't possible... everyone I've ever spoken with, the parts catalogs, and my personal experience agree with that the split was somewhere late in 90 or between 90 and 91. My bet is that someone swapped in an 87-90 transfer case and transmission as a pair when one or the other died, sometime before you bought the vehicle. This isn't really too surprising, everything bolts up if you do that to a 93. Any chance you could get the part numbers and datecode+serial number off the transmission and transfer case?

[Norsk62]

Nope. I'm the 2nd owner of this vehicle and I bought it from the original owner. So it's bone stock and unmolested.

However, the guy that rebuilt my T-case told me it was a 21, and installed a 21 spline input shaft. And since I think he's a dumbass anyway, it does not surprise me that he is wrong and it is a 23 spline shaft.

Thanks for the info, now I have to get my hands on a 23 spline input shaft for my NP231 t-case and fix what this guy did.

[kastein]

If it went back together he did the right thing and "forgot" to tell you, or he swapped out the transmission as well. A 21 spline input is smaller diameter than a 23 spline output shaft and it won't even slide over, it's impossible to bolt up the wrong spline count case to a 23 spline transmission as far as I know. The other way around is possible (accidentally putting a 23 spline case on a 21 spline transmission) and you won't realize your mistake till you start the vehicle and go nowhere because the 21 spline shaft spins freely inside the 23 spline input gear.

[casm]

Originally Posted by kastein

Just know that there was a BA5, BA10

Just one thing: to the best of my knowledge, Peugeot did not made a BA5/x transmission.

In XJs and MJs, the BA10/5 was used; some 4-cylinder Peugeot cars used a BA7/5 (or, if early enough, a BA7/4). The first number is something of a relative strength indicator, with the second number being the number of speeds. There was a 10/4 as well, but that never made it into XJs (or, I believe, anything Peugeot sold in the US market).

[kastein]

Originally Posted by casm

Just one thing: to the best of my knowledge, Peugeot did not made a BA5/x transmission.

In XJs and MJs, the BA10/5 was used; some 4-cylinder Peugeot cars used a BA7/5 (or, if early enough, a BA7/4). The first number is something of a relative strength indicator, with the second number being the number of speeds. There was a 10/4 as well, but that never made it into XJs (or, I believe, anything Peugeot sold in the US market).

My mistake. Apparently I've been misreading it all along, I thought people referred to a BA5 or BA10 when saying BA10/5...

I have no experience with the pukegoats as most RENIX era jeeps up here rusted out like ten years ago, so I never realized I was being an idiot till you said that.

[cruiser54]

Originally Posted by ehall

I think the Power mode does go into Overdrive w/ TC lockup afterwards and I probably just left off the last shift in my previous notes. I used a Snap-On scanner to watch the differences but I didn't make very good notes.

For those of us with Jeeps that have a defective Power/Comfort switch, there is a simple fix. If the switch fails you'll be stuck in Comfort/Grandma mode.

Simply remove the switch and unplug it. There are three wires in the harness plug: Black, Tan, and one with a stripe. Make a jumper and install it into the cavity for the tan wire and the striped wire. Leave the Black one alone.
Be sure to check the "trans" fuse in the fusebox as it may be blown due to the old shorted switch. If that fuse is not replaced, you'll default to Comfort/Grandma mode.