4.0L auto trans ... the transmission shifts by itself when your driving down the road.. sometimes it just goes out of OD and you have to stop, shut down, restart, in order to get the trans back.. sometimes when you startout, your in 3rd, so, you have to manually shift 1st, 2nd, and so on.. with NO OD.. sometimes it just hick ups like its shifted to neutral and back real quick, you never know what its going to do.. 3 trans shops have gone through the transmission, say the tranny is perfect, no problems.. I've changed the TCU, 3 solenoids in the trans, the speed sensor, the ECU, opened every connector, cleaned and put NO-Oxide in them.. I'm at a loss, haven't a clue what to look for.. sometimes its like someone pulled that 10@ fuse under the hood.. if anyone has an idea, or an FSM for this model, let me know.. thanks.. wayne

 

Is the fluid Mercon/Dexron III ? Any other fluid can cause shift issues.

 

Assuming the correct fluid, level and quality: how does it go when you shift manually?

 

Which Speed Sensor, Input or Output?

What is "No-Oxide"? Hope it's not Ox-Gard or NOALOX.

 

its a non-oxidizing grease we use in telecom work.. used it for 50 years.. the speed sensor was on the carb or whatever that thing is in front of the injection..

 

whatever they put in it at Chrysler/Jeep in Las Vegas.. then Performance Trans replaced it when they went through the tranny, next St. George trans replaced it when they went through the trans... they're the ones that changed the speed sensor, 3 solenoids... I changed the TCU and the ECU

 

when you pull the fuse under the hood, you have to shift manually, works fine, doesn't slip or shift by itself.. when it jumps to drive3 from the get go, you have to manually shift to get it going.. works ok that way..

 

Link to FSM in your private messages.

 

Go here and see if you can perform the tests outlined in post #13,

https://www.cherokeeforum.com/f2/tra...-shift-195148/

 

my TCU plug doesn't match up to the drawing at this link? mine has 16 upper and 16 lower pins.. ?

 

Sorry for misleading you.

I see now that you have a '96, not a '98. That TCM you show is a '96 part number.

When I went to the forum index it said "tranny problem HELP '98 Cherokee Sport ", but I didn't notice that when I opened the thread the header said "tranny problem HELP '96 Cherokee Sport w/4.0L".

I don't have a '96 FSM so I can't show you the '96 TCM pinout.

 

That is not a speed sensor on the Throttle Body. The shop probably changed the Throttle Position Sensor, which is mounted on the TB.

 

Here's a TCM connector pinout for the '95 XJ, which looks like the wire colors and pins match the '96 TCM connector photo you posted.



The Transmission Output Speed Sensor (OSS) is mounted on the left rear of the transmission. The TCM depends upon the output signals from the OSS for transmission shifting.

You could try reading the resistance of the OSS from the TCM connector.

By the looks of it, you would read the resistance between pin cavity C3 (+) meter probe, and cavity D7 (-) meter probe. Set your Ohmmeter to 2K (2,000) Ohm scale.

I don't know what the resistance is supposed to be but if you get an Open or read very high resistance I would think the OSS is defective or the wiring from the TCM connector to the OSS is bad.

Do this and get back.

 

If this is "Dielectric Grease", it may be causing problems. The XJ electrical connectors (pin/cavity type) do have problems with marginal connection between the pins and their respective cavities, and Dielectric grease being an insulator will only agrivate those marginal connections. Connectors used in the telecom industry may be better connectors and less sensitive to using Dielectric grease.

I would recommend removing that grease from each connector you put it in and clean out both the pin side and the cavity sides using CRC QD Electronic Cleaner.

 

so, your saying replace the OSS before replacing the TPS? If I go ahead and replace both of these, is there any other little items like this hidden away that may be the cause? I bought the TPS last night at NAPA, so hopefully the OSS is easy to get to and not going to break me..