I have a 99 regular cherokee 2wd (dont laugh) , cost only 400 bucks
Here is the problem, my transmission will very rarely go into over drive (4th gear), if it does then it may at any time drop back out.

* Here is the brain twister. I have learned that I can get it to take overdrive if and only if I drive to over 45mph, then while moving at that speed, shift to neutral, turn key off, count 5 seconds and then restart engine, shift back to drive. At that point it will shift to overdrive, if I coasted to under 40mph, it will still shift to overdrive once I accelerated above 42 or 43mph or so. This works 100% of the time without fail.
Also it will work all day long unless I shut the engine off or sit in park idling for several minutes.
Stopping at red lights etc, seems to have no effect, it continues to run the shift range properly. If I shut the engine off or sit in park for some time then I will have to once again shift to neutral at ANY speed above 45mph, shut off engine, wait a few seconds and restart, shift back to drive and overdrive will work as it should.
It is also definitely overdrive, not torque converter lock-up that I am referring to.

Any ideas?

 

The transmission in my XJ has two types of overdrive. At 35mph it will shift in OD but not lock the torque converter. At 45mph it will lock the TC and be in OD. Check your TV cable and make sure it's adjusted properly. You can try at 40 mph pull the shifter from D to 3 and see if the RPMs change.

 

My thoughts exactly.

 

Ok I just did a few test runs to record the data. First I fresh adjusted the TV cable, it looked proper but I did it anyway just for good measure.

As I accelerate, right at about 2000 rpm the torque converter locks up dropping my rpm to about 1800 RPM at 40 MPH or so. I can go on and accelerate to 50 (about 2200 RPM). At 50 I dropped to D3 or 3 and no change in RPM.

I did that a couple times to confirm.

After that I once again accelerated 0 to 50 slowly to feel and see all the changes, at 50 it remained in 3 so I proceeded to shift to neutral, turn key off then restart engine, shift from neutral to OD and then at 50 my RPM drops to about 1600 or 1700 RPM. At this point it will work all day long so long as I do not turn the engine off.

Someone once told me to check and clean my NSS however I do not see how that would affect shift solenoids unless it does more than prevent starting in gear. I need to get around to cleaning it anyway though because my Backup Lights will not function and I can't find any other reason why.

 

Actually, it's not a NSS, it's called a Transmission Range Sensor (TRS). When a gear is selected it 'tells' the TCM what gear you have selected and it will use the proper solenoids to shift the transmission accordingly.


You can test the Range Sensor, and other TCM inputs, from the TCM connector.


Use a digital multimeter for the tests and safety pins as probes for the pin cavities in the TCM connector.


Read the connector pinout sheet and the procedures sheet carefully before beginning.


Pin Out Sheet:





Test Procedures:

 

I have church in the morning but I hope to find time tomorrow to perform the required tests. yes, I am familiar with my DMM and I hope we find something here. If I can not get to it tomorrow evening it will be next friday before I have time to tackle the recommended diagnostics, however I will do it , record and reply with the results. Thanx so much

 

Peace be with you.

 

I just posted I could not locate it , and literally 5 minutes after I posted I found another site and it was accurate on the location.

 

The TCM is located under your dash to the right of the steering column. You have to remove the plastic trim panel and steel knee blocker from under the steering column to get at it.


It looks like this:

 

This is my first image insert I hope it looks right after I insert.
I located the TCM and performed the tests as prescribed.


#4 under Specific Resistance checks is a hair above range.


Everything else seems to be good except #'s 3-6 under Specific Voltage Checks. It says to read battery voltage but does not specify if I am expecting battery voltage or some range of it. (I performed these checks with the key on and gear selector in the respective positions).


While disconnecting the Ground from battery I found a broken Battery ground to firewall lead, repaired it, actually relocated it because it was short to go to OE location.



I did not have the pin adapters for my Sperry DMM so I searched the house, found one sewing needle and one large arc suture needle, it worked with a little finesse.


After completing the required tests I then applied dielectric grease into the female side of the terminal and reconnected it.


I must note. I literally did no repairs at all other than fixing a missing ground from battery to vehicle battery and applying grease to terminal pins.


I started the Jeep and took it for a test drive. To my suprise it shifted correctly all the way to the store and back. However it in rare occasions will do this but usually if it actually takes OD on its own it drops out after 15 secs or so.


I will need a couple days to see if the problem truly rectified itself or tonight was a fluke.


However like I said, I am concerned about the "Specific Voltage Checks" #'s 3-6 as I am not exactly what voltage to expect, it seems to imply B+ but I am not sure and my reverse lights still do not work.


**** NOTE: All OHM Readings were taken at the 2K range as my 200 OHM Range seems to be malfunctioning.

 

I want to also note for anyone else attempting this that I preferred inserting the pins from the "Wire Side" of the connector rather than the "Pin side" because it seemed to make better contact without wrestling around so much.

I was also concerned about stretching my female terminals.

 

Update: The problem did not resolve itself.. of course.

I again went to the store tonight and my jeep refused to shift into D4 , I played around with it, many speeds, RPM ranges etc. I finally gave up, cruised up to 50 MPH, shifted to neutral, killed the engine, then restarted and shifted back to D4, it proceeded to shift to D4.

I was absolutely hoping cleaning contacts and a ground wld have resolved the problem but it did not.

That leaves me with the lack of voltage in the #3-6 tests.

What does lack of voltage in those ranges mean? If anything.

 

It means the TRS (NSS) needs to be rebuilt.

BTW, do not use Dielectric grease in any pin type connector, it will only aggravate any existing marginal pin-to-pin cavity connection.

 

I like OxGard.

 

So do I, but only on wire terminal ground connections. It would a kiss of death to put it in a pin type connector.