Everything you ever wanted to know about the AW4

[lawsoncl]

I just got done staring at the 97 and 98 FSMs to refresh my memory.

If this was me, I'd just stick the 98 TCU in there and add in the wiring for the front sensor. Based on reports about a 97 working in a 98, I would guess going the other direction would play nice with the ECU and not throw a code for a missing TCU.

The 97/98 TCU wiring connectors pinouts are identical except the 98 wiring has pins 1 and 2 going to the input speed sensor, and pin 3 is used to give the output sensor ground it's own ground wire. The solenoid/sensor connector at the tranny changed from a 6-pin to an 8-pin to accommodate the extra two wires for the ISS and the OSS having it's own ground line.


kikilink333 - PM me with an email address, and I'll send you the pinouts from the FSMs to help match up wires on the 6 and 8 pin connectors you asked about. I even have a 98 TCU and it's wiring harness connector sitting on my desk if you need it.

 

[kastein]

Yeah, you would think that... so did I. It catches you when the NSS says you're in drive and it sees various speed sensors indicating movement, but the pulse rates don't agree with the gear it commanded. I found this to generally happen on 2nd to 3rd shifts and vise versa when I was working on "blue pilling" the TCU. I think there is probably a solution but I never got around to figuring it out and ended up swapping my labrat 98 XJ to a manual with a manual ECU I found in the junkyard one day, so I haven't messed with it since. Basically you can get rid of the solenoid electrical codes with resistors, but the solenoid function codes proved to be a bit more difficult to dispose of, even fooling the TCU into thinking it was in neutral or park at all times, which should have gotten it to stop trying to shift or check the selected gear ratio against the ISS/OSS signals.

 

[Shadowdrop]

Hey guys, here's a different scenario for you: I have an old International pick-up that came stock with a 258. I have a 4.6L stroker from a '94 ZJ I plan to swap in complete with ECM and fuel injection. I'd like to also swap in a 2WD AW4 to replace the old 727. I found a good deal on an AW4 out of a '98. I would use a '98 TCM with the trans. My question is: Will a '94 ECM and a '98 TCM play nice together? Would this be the simplest solution to combine this engine/trans combo, considering I'll be re-wiring the entire engine bay? Thanks all!

 

[kastein]

The 94 ECU won't care at all about talking to the TCU. You can go a few routes here
- use 94 ECU, 98 TCU, don't even wire the ccd buses together, give each the signals it needs, be happy.
- use 94 ECU, 94 TCU, 98 tranny, build lawsoncl's nifty little circuit, don't wire the buses together, etc
- use 94 ECU, make your own TCU, these aren't difficult trannies to control.

Another bit of info for you - get the vehicle speed sensor from an 88-93 dodge dakota. It will take a long (93 down style) jeep speedo gear, and has a standard 5/8-18 output for a mechanical speedo cable, so you can get your factory IH instrument working without eliminating the electric VSS. The ECU will want a VSS signal, it will act wonky and set the check engine light if you don't give it one, and this is easy and pretty cheap. The sensor is 2 wire and should be wired from the ECU's signal input pin to ground. That handles 2 of the 3 VSS harness wires - the third is a voltage supply for the original 8 pulse/rev hall effect VSS. Since the Dakota unit is an 8 pulse per rev reed switch, just wire the voltage supply to a 470 ohm resistor, tie the other end of the resistor to the VSS signal wire to pull it high when it isn't pulsing low.

If you need a 7/8-18 thread to put your stock speedo cable on (this is more standard for speedo takeoffs, 5/8 is usually the dash end) either you can have a threaded sleeve made with 5/8-18 inside and 7/8-18 outside, or you can just grab exactly that off one end of the cruise control VSS immediately behind the instrument panel in an 87-90 XJ/MJ. The bushing they use is just such a thing, and exists for the same exact reason.

There are a few other ins and outs on this. For instance the starter solenoid is powered by the rear defrost grid fuse in the XJ PDC, so don't take that one out while stripping the unnecessary wiring from the harness and wonder why it won't crank after your swap :dunce:

I did a factory-detailed swap of a 4.0 into a friend's originally carbed + mechanical speedo 87 YJ, and kept the EFI completely functional (I even installed a CEL, which remains off unless there is a problem), which is very similar to what you're going to be up against, so let me know if you have any other questions. My PM inbox is perennially full, but I usually check in here every few days and my username on facebook is the same as here.

 

[lawsoncl]

- use 94 ECU, 98 TCU, don't even wire the ccd buses together, give each the signals it needs, be happy.

My vote, as it's simplest. The 94 would be OBDI and the 98 OBDII, so I'm not sure what would happen if you connected the data bus lines between them anyway.

I'm assuming that 98 AW4 is from a XJ since the ZJ would have had a Chrysler 42RE auto.

 

[Shadowdrop]

Excellent, thank you guys! Now if only this guy on Craigslist would respond....

 

[mypantera]

sorry if this was already addressed and I missed it....

I am helping a friend install a 2000 AW4 into a 92 YJ. The TCU is from the 2000 as well. The tranny is in and working good, it shifts automatically or manually depending on shifter position as it should. It will start in gear but that is not a concern for the moment. The only issue we are having is that it will not kickdown. We have adjusted the kickdown cable per the instructions, even trying adjusting it longer and shorter with no change. It doesn't matter if the cable is connected or not. It does feel as though it is connected in the trans and not broken or binding. The TPS on this engine is not adjustable (newer 4.0) however we did change it with a known good one and no change. I am not sure what to try or check next.

I did all the wiring and connected everything from the TCU to the two tranny connectors per the 98+ wiring diaphragms and made the following connections to the YJ wiring harness:

Pin 16 TPU to pin 6 YJ CPU (Sensor return)
Pin 17 TPU to pin 22 YJ CPU (TPS)
Pin 23 TPU to pin 29 YJ CPU (TCC brake)
Pin 24 TPU to pin 11 YJ CPU (ground)
Pin 25 TPU to pin battery (12+ fused)
Pin 26 TPU to pin 9 YJ CPU (ignition run/start)

Any help you can provide is great appreciated

 

[Varnish]

Another 2000 AW4 swap issue. Tranny shifts on its own fine but the torque converter will not lockup.

I've got a 2000 XJ 4.0/aw4 swapped into an '86 CJ7. I took both together so did not have to mess with the tranny wiring much to PCM. I have the brake pedal hooked to a relay which provides ground at all times to the tcu brake sense and pcm until the pedal is pressed and then it is open. I read earlier in this thread that it should have 12v when you press the pedal but don't think that would cause my issue because my issue is during cruise when the pedal should not be pressed. Initially I had the brake pedal send an open when not pressed and a ground when pressed but it hasn't made any difference since I changed it.

I have a light hooked up to the torque converter solenoid wire to ground and it never lights up. I have jumped 12v to this circuit while driving and it does lock the converter and lights the light so I know the wiring, torque converter, tranny, and solenoid are good. I have the obd2 connector working fine and it is telling me no codes and all is happy. I have made sure the engine is up to temp and the computer temp sensor reads correct (according to dashcommand obd2 reader app).

Tranny only has about 30k miles on it but sat for 10 years. I replaced all fluid and filter which looked good. I am at a loss as to what to try next. I have the PCM's neutral safety switch permanently grounded, does the tranny know this? It sounds like it has its own shifter position sensor (which is next on my list to test out). I am using a '91 YJ vehicle speed sensor to tell the PCM the speed and it is about 10mph slow but I have had it up to 50mph and no lockup. The tranny doesn't use this signal does it? Again, it seems like the tranny has its own speed sensors.

I guess I just need the perfect checklist that has to be satisfied for the TCU to lockup the torque converter if somebody knows this for a 2000.

 

[kastein]

Mypantera, I will have to think about yours and do some pin checking later today if I get a chance.

Varnish, cool swap. That YJ sender is the same part number, different application as the dakota one I suggested, I just couldn't get a straight answer on what year of YJ uses it so I tell people it is a dakota part. I would hazard a guess that either your brake pedal switch wiring or NSS trickery are responsible for the lack of lockup, but unsure which. Can you draw a quick napkin schematic of how you have it wired?

 

[Varnish]

Not quickly as I wired the whole thing over a year ago, just took a long time to get the rest of the jeep on the road. I'll be troubleshooting it some more this weekend and will get back on exactly how I have it wired - I'm just running out of ideas to check. Its mostly factory wiring for the tcu since I took the engine/tranny combo, the engine's PCM is where a lot of the work went. From what I can tell though, things like the brake sense wire is shared between the PCM and TCU - the XJ brake switch fed both at same time.

 

[Varnish]

Turns out I didn't do any NSS trickery, its all stock between the tranny and pcm, I was thinking of something else. Good news is the torque converter lockup is in fact working and my brake switch relay also is working - when locked up I can tap the brake pedal to turn it off. Turns out I just needed to go on longer highway drives to get it to lock up. Bad news is that the engine bogs pretty bad once it does lock - like at 55mph I'm at 1200rpms. I'm thinking this is likely due to my speedo gear being off, at least I know the internals and computer are happy now.

 

[Goose_XJ88]

Ok so I'm back. I've decided to not get the 01 AW4 in order to save the headache of the tail rebuild or the electronics box trickery.

Planning on going with an early HO AW4 (91-94) to get the 23 spline output and plug n play into my RENIX harness.
My next question is regarding the helical gear cut change. Does this cut change effect the splines that contact the
trans output, or the mesh of the planetary inside the t-case?

If any of my assumptions w/ the plug-n-play or anything else is wrong please let me know. Really appreciate all the knowledge and time in this thread.
Plan:
-88 Cherokee 4.0
-91-94 AW4 (to stay away from OBD I and II. Does OBD I/II trans make a difference? Or does that only apply with an OBD I/II engine?)
-01 231J w/ HD SYE

 

[Varnish]

Bad news is that the engine bogs pretty bad once it does lock - like at 55mph I'm at 1200rpms. I'm thinking this is likely due to my speedo gear being off, at least I know the internals and computer are happy now.

Turns out my axles are 2.73, ugh, 4.56s on order!

 

[kastein]

Ok so I'm back. I've decided to not get the 01 AW4 in order to save the headache of the tail rebuild or the electronics box trickery.

Planning on going with an early HO AW4 (91-94) to get the 23 spline output and plug n play into my RENIX harness.
My next question is regarding the helical gear cut change. Does this cut change effect the splines that contact the
trans output, or the mesh of the planetary inside the t-case?

If any of my assumptions w/ the plug-n-play or anything else is wrong please let me know. Really appreciate all the knowledge and time in this thread.
Plan:
-88 Cherokee 4.0
-91-94 AW4 (to stay away from OBD I and II. Does OBD I/II trans make a difference? Or does that only apply with an OBD I/II engine?)
-01 231J w/ HD SYE

The helical cut I mentioned is the planetary gears inside the case, the splines are straight. Your plan will work, I see no problems with any of the part choices you list.

OBD 1 vs 2 isn't quite so clearcut. 91 through 95 are OBD1, except some very rare late 95s that got extremely rudimentary OBD2 according to my info, though I've not seen evidence of this. 96 through 01 are OBD2. The important year split for AW4 concerns is 97 down vs 98 up, the OBD2 retrofit was rushed and came in a few phases. 96 got a slightly smarter TCU that fit where the old one did, and a new ECU. 97 got a significantly smarter TCU that works with the old tranny sensors except for a new NSS design. In 98 they finally modernized the tranny by upgrading the OSS, adding an ISS, and improving the TCU's ability to detect what gear the transmission is actually in, rather than making some assumptions as it had to previously. This multi-phase upgrade of the transmission and engine controls is what allows us to play tricks with it, but also what prevents other tricks, or results in needing to play tricks in the first place. Aint it great?

 

[Goose_XJ88]

Just super...lol Thanks for the help Kastein I appreciate it. tryin to do this all without this forum I would be so lost... Then again, without this forum I would probably be ok with my 242...haha Onward with the upgrades.

 

[mypantera]

We ended up switch the trans for a 96 version and wired it accordingly. Everything is working good.

 

[ktfung]

Aw4 question , 2 weeks ago i did the Moab Fall Fling and on the way home passing through Salt Lake city I 15 and i was doing about 65 mph then suddenly my xj speedometer needle jumping rapidly between 60-85 mph and at the same time heard a loud banging noise in the drive train and lost power for about 3 seconds then as soon as the banging noise is gone and the power came back on . It will do that once every half hour but later i found when not too much traffic late at night as long as the engine rpm is around 2000 rpm then no power loss or banging noise but however with 4.56 differential gearing and 35 inch tires that means the jeep can only go about 50 mph . At that speed is kind of unsafe when the speed limit in northern Utah is 70 and Idaho I 80 is 80 mph . So i just chuck along around 2300 rpm and GPS said i am doing 65 mph and after 1000 miles of driving and about 40-50 bangs then got home . First replace the vehicle speed sensor on the np 242 transfer case and speedometer is working fine now and no more banging noise on the freeway but around town driving between 25 - 40 mph and when the engine is cold and now i can hear my 96 with only about 80,000 miles xj AW4 is making a gear grinding noise and lost the forward momentum for 2 seconds . However once the engine warm up and you drive all day long nothing will happen and it is shifting fine and no slipping at all but 2 or 3 days later when engine or transmission is cold that gear grinding noise will come back for 2 seconds . Any insights or possible simple fix ?

Thanks in advance

 

[kastein]

Doesn't sound like there will be a simple fix, sorry. I would bet on internal damage to the transfer case or transmission. Check your driveline parts too.

Loud banging usually means "it's hashed".

 

[ktfung]

Although i have another used AW4 from A WRECKER 1998 XJ . bUT IF that noise doesnt get worse or effect the operation of the transmission then i guess i can live with it because it is a big job to take the tranny out when i have a Klune 4-1 underdrive with the stock np242 plus the TNT long arm front suspension with its own transmission and transfer case skip plates . Last time it took me about 4 weekends spare time to install everything

 

[Shadowdrop]

I picked up a 30-43LE AW4 (2WD) from an '01 Cherokee. Things I'm going to have to sort out:
1) the TCM plug is different than the one on my '94 wiring harness. Doh!
2) no trans dipstick or tube extension included. Did these change at all between years? I'd imagine not.
3) No slip yoke included. Will a yoke from an A340 work? I can find an SC300/400 much easier than a 2WD Cherokee at the pick-a-part.