AW4 issue!

I will make this as detailed as possible so please read carefully.

my '92 XJ is SUPPOSE to have a '98 trans (according to the previous owner). Can not confirm that for a fact.

I have had the XJ for the better part of 5 years now and not had any issues with it until recently.

My little brain can only take so much thinking on its own, so I need 'yalls opinions on this situation.

It only acts up once warm, in other words IT OPERATES AS IT SHOULD UNTIL IT WARMS UP. What happens is that it quickly upshifts into 4th and stays there, and it will never lock the torque converter. I come to a stop it stays in 4th, I take off at whatever speed its 4th gear all day. Once it cools down it will operate fine until warmed back up. If I let it sit for 2 weeks or more, it takes longer for the problem to occur.

if I take out the TCM fuse It shifts fine mechanically (obviously no TC lock up, but that is normal operation with the computer unplugged).

So, I ohmed my solenoids, sure enough 1 was out of spec. I replaced all the solenoids with junkyard ones, including the underdash computer! The same problem occured. I then bought a brand new complete solenoid kit (all 3) and installed them including a new filter and trans fluid. The thing shifted smoother than it ever has at the correct points and everything. Until it warmed up, it started doing the same thing AGAIN.

I then adjusted the throttle valve, no change. Same issue

I checked the TPS with a DIGITAL volt meter, swept just fine in my book. So, i had a spare TPS and swapped it (just in case). Like clock work the transmission warmed up and shifted to 4th and stayed.

At this point I swapped the stock computer back and then used this article http://www.transonline.com/transdigest/magazines/1997-10/Shift Pointers/index.html to pin out each wire. When I performed the test I made sure the trans was good and hot and acting up. I did the test precisely the way it is explained. The C-9 test did fail. I have no idea what the means, but it registered at .4 volts.

I also looked at this http://mysite.verizon.net/~chris83803/AW4_OBDI_Connector.jpg and it seems everyone that has the C-9 failure also has no reverse gear or reverse lights. Seems to me that indicates a bad NSS. I don't have any NSS failure symptoms! all the lights work correct, the thing starts fine when in park, hot, cold it doesn't matter!

with all that being said we learned:

*Once the transmission is warm it shifts into 4th and stays in 4th with the torque converter forever unlocked. Once cooled back down the transmission operates as it should. When sitting cold for a long period of time it takes a bit longer for issue to arise.
*Swapped solenoids with junkyard, and then NEW IN BOX-no change
*swapped computers-no change
*checked and swapped TPS- no change
*adjusted throttle valve-no change
*pulled fuse-trans functions manually as it should (with no torque converter lock-up)
*read a few articles and checked connector (WHEN HOT) with attached article as a guide-determined C9 failure
*It seems I have no common symptoms of a C-9 failure
*new trans fluid and filter

Obviously not all hope is lost, but my brain is fried for the night.

I guess it could be a VSS? I will check into a bit more. I need to sit back and read someone elses view on it for now!

thank you guys so much for reading this! Everyone on here always has the best information if you take time to read it. Maybe I'm overlooking something simple...:cheers:

Sure sounds like turbine output speed sensor is your next move..... Pre 96 AW4 trans only had the rear output speed sensor if memory serves me right... I honestly have to say I have changed only one output speed sensor in my life on an AW4 XJ..... the output speed sensor on the AW4 is on the drivers side at the rear almost in line with the t-case vent tube coming out, just foreward of that... you can see it behind the 4x4 shift bracket bolted to the trans.... you have to remove the 4x4 shift bracket off the trans to change it out..... Also in 1996 and newer Chrysler added a front input speed sensor and the rear speed sensor changed from a 1-pulse/rev reed sensor to a 4-pulse/rev magnetic sensor. For this reason, if you are planning a swap you should try to keep the same year wiring harness and computer.
Also I have run into a bad ground for the TCM, if the TCM is bolted to the knee bolster make sure you have good screws on each end and not stripped out.... I have run into missing bolster end screws or stripped screws causing a not so good ground.... I had a 1994 XJ many years ago that had about 70k on the clock, it was under warranty... When it was hot it would go into neutral at freeway speeds, I spent days checking this,ohming that and changing everything electrical I could except the electrical harness... I ended up pulling the trans and having the tranny guy overhaul it with new seals, front pump and convertor.... that is what fixed it... he never found anything obvious like a torn, brittle or flat o-ring.... but that fixed it......

It also really helps the to have DRB scanner for these, you can watch alot of things going on the TCM sees... but not everybody is lucky enough to have a DRB.... I am blessed I ended up with one for my 1990 XJ many years ago when the dealership I worked at decided to purge old tools.....
I hope this helps, I dont remember everything and kinda rusty, been 10 years since they quit making the XJ and I left the dealer in 2009, some refresher stuff I found on Google......... Best of luck and hope you repair it :wave1:

That C9 pin testing failure is relevant to this, I'm sure. Pin C9 is connected to the D sense output on the NSS, your TCU may think your gearshift is in 3. Not sure why that would cause the symptoms you have, but I believe it's related. Try cleaning the NSS.

It's really odd that swapping the TCU and solenoids hasn't fixed it - those are the things I'd suspect.

Thanks so much guys! your heading me the direction I wanted to go! haha. I will try and work on it tomorrow for a bit. Sorry for a lack of quick response. One last thing. I did put an SYE on this thing and it wasn't but a few weeks later the problem started occurring, probably about 600 or so miles later. Isn't there a speed sensor in that deal, and doesn't it need to be indexed properly?

The Vehicle Speed Sensor is in the TC and that should not impact the transmission. I would give the NSS a good cleaning just to eliminate it. Prior to cleanining mine, I had all sorts of strange shifting issues that all went away with the clean.

Not saying that it is definitely the issue at hand, but a good cleanand regrease (use dielectric grease here) certainly won't hurt it.

But to be perfectly transparent here, I know way more about the OBDII Heeps than the older ones.

Trust Kastein...

Well, the NSS was not the ticket. Cleaned and replaced it and still the same thing happens. Onto the VSS. One good thing, on my test drive I stopped and spent $6 on scratchoff tickets at the gas station and won $10, so I'm $4 up on the day! haha

Well, I'm not messing with it further tonight. The trans is hot as well as the exhaust and I have no reason to be burning myself to get the VSS out. However, I see that its held in by a bolt and fork style bracket. The sensor seems to have a lot of play back and forth side to side when sitting in there. Can anyone confirm that this is normal?

I had the same problem. At the time I did the solenoids I also found a bad pin in the connector to the trans near the dipstick. In the end I replaced a worn out NSS as it broke removing it, a used TCU,and all 3 solenoids. Each helped a little though the solenoids got rid of the hot stuck in 4th problem.
To eliminate the VSS just unplug the wires to it and see if theres a difference.I will bet there is no difference.
Ron

Have you ever had trouble with, or replaced the Throttle Position Sensor? I know it's a long shot, but I've had strange shifting issues with a bad TPS. One night driving home from work, you'd have sworn the tranny was about to grenade, shifting all over the place, no lock-up, and it was the TPS. I know it sucks to keep throwing parts at your ride, but I got a bunch of them at the yard for $5/a piece, so it's cheap. '91 to '96, XJ or ZJ 4.0 are the same part #, with the same plug.

I will unplug the VSS first before trying to remove it. I have already addressed the solenoids and the TPS if you read the original post. I have no reason to believe the NSS is bad. When I pulled it out it already seemed pretty clean and operating correctly, but still I serviced it and put it all back together with no change. I'm not the guy to keep throwing parts around to fix something, so it will sit here not working correctly until I figure this shit out.

One thing I do want to check though before I confirm-I want to say when it was acting up I could shut it off, and then when I go to refire it up while everything is still hot it acts almost like its in gear, the idle doesn't free-rev when firing up, it just starts and immediately goes to idle...which moves me back to the NSS route. Again I will look into this more and more. Please, keep the ideas coming!

Joshooha said:

I have already addressed the solenoids and the TPS if you read the original post.

Click to expand...

I've had a brand new, quality brand name TPS bad right out of the box. I have also had one or two 'previously loved' pieces from the yard act a little strange. Yes, they 'swept' nice when bench tested, but every one of them started and finished at different values, so I don't know which one was the closest do the ideal readings. Maybe I'm fortunate that with four XJs, we've never had a frustrating tranny problem. But I was getting most of your symptoms, in addition to stalling and unintended acceleration, in my '96, when the TPS was acting up. Good luck with your hunting, and please post up any progress, to keep those of us in for the long haul up-to-date.