Intermittent OD (4TH) Issue

Hey all, first post here, *woohoo* :clap: A Swedish 23 year old Jeep maniac here with nothing else to spend my time and money on. :loveu:

First off, I've researched the diversity of the internet and found many threads concerning my issue, but for the sake of getting a general sense of common failure, I thought I'd contribute with my issue to history as well for future purposes.

Info:
It's a Cherokee '97, AW4, NP242.

My issue is a very intermittent loss of OD /4th.
I noticed at first, that on my way home from work, the lockup wouldn't let go. I thought it was odd, so I tried it out and indeed it didn't let go of the lockup when coasting, even shifting down to 3rd it seemed to keep it engaged, until I finally slowed down to say 30 mph, it finally let go and the Jeep didn't stall.
I figured it could be related to the TPS, and since I had some other weird throttle-related issues, I ordered a new one from Mopar, thinking that thing was probably worn out anyway.
That issue went away, and I haven't delat with it again since.

After replacing the TPS, I drove it around and I noticed that it didn't upshift to 4th, it went way up to 60 without upshifting (didn't try any faster).
I slowed down, tried jerking the gas pedal to make it upshift but I wouldn't. I stopped, shut it off, started it right up again, took off and OD was back.

Didn't think much of it after that, I figured if it came back, I'd have to continue the troubleshooting. I had actually pulled the neg. terminal, so I figured it might be a relearn thing or something.
Now after many miles and roughly 1-2 weeks later with absolutely trouble-free driving, today I found that I had no OD again. I went to the gas station first, and on my way there I had OD just fine. Drove off with a fresh engine start, and on the highway I noticed the lockup was engaged, but in 3rd - I could feel that the transmission didn't slip, but I wasn't in the 4th gear. I stopped on the side of the road, restarted it (like a good ole PC)- took off and I had OD again. Drove it with over 10 start-shut cycles after that today, with no issues whatsoever.

Now: Since I got the Jeep, the reverse lights pretty much never comes on. I have managed to get it going a few times after jerking the shifter a little. Sometimes even that doesn't work. So with the neutral safety switch acting up, I'm thinking this could be the issue?
I tried simulating a faulty brake switch going down the road to see if I could provoke my problem (slightly tapping the pedal while keeping up the speed). That left the 4th engaged but unlocked the TC.
I tried putting it in 3rd and see what happened from there, and that exactly resembled my symptoms; 3rd, with lockup. As I moved it from 3rd to D at that test, it went back to 4th with lockup as it should.

Things I've checked/replaced:

* TPS (Mopar) - put on without any guidance towards any rotation on the axis

* Adjusted the TV cable: Plunger all the way in, clip down, WOT on the TB, not pedal

* Checked the fluid, up to level, recently replaced with filter, smells and looks perfect

* (Sorta) Checked the brake switch. Haven't messed with it anything but trying to depress it while keeping throttle in 4th on the highway. I had a blown brake light fuse though a few weeks back... coincidence?

Let me know what you think and whether or not you think it could be the NSS robbing me of my 4th! :worship:

Welcome!
The brake switch can and will cause shifting issues, especially with the Converter.
Shift solenoids could be culprit was well.

Thanks!

I have further driven it, and today on my way to work I found that it showed its 2nd symptom again. It goes in to 4th and locks up great, BUT- It doesn't let go of the lockup when I let off the gas.
I tried stopping, and kind of jiddering the gas pedal to see if there was play in the TPS, but it didn't help. I tried putting it in 3rd and let it lockup, to see if it did the same in that gear, and it did. It didn't unlock the TC either going 50 mph in 3rd. I then tried upshifting to D, letting it lockup and I pushed the brake. The TC immediately unlocked super smooth and without weirdness. I let off, and pushed the gas a bit more, and it locked up - but didnt unlock when I let off the gas again. It's like driving a manual in 5th and just letting of the gas, coasting on the engine. I didn't have time to stop and restart the Jeep as I was heading for work, but I reckon that would've helped. I get no CEL at all, which I think is weird. Obviously this is some kind of electric issue. If the issue was with the valvebody/ solenoid assembly there would be issues with unlocking from the brake switch too, right?

I kept digging in my head, trying to backtrace when this started, and it turns out there is a very strong memory of it appearing right after I replaced the TPS, for other reasons that I thought might be related to the TPS. I had some performance issues after an engine bay wash... now looking back, that was probably ignition coil or something alike. Anyway the part is a Mopar TPS bought from the dealership, but if it might be defective or put on wrong by me (at a tilt?) - could this cause such problems? I also read online that if the TCM reads a circuit issue it limits you to 3rd until you reset it (restarting the vehicle) which mine does sometimes.

Luckily I still have my old TPS. I'll try it on today and see what happens. I'll also squirt some electronic cleaner down the connector while I'm at it to be sure.

** UPDATE **

Alright, I put my old TPS on, and since, I haven't had any issues with no 4th or refusal to unlock when letting off. It seems that the issue was in fact a factory bad TPS. I also cleaned the connector with some electrical cleaning spray just in case.
It can still hesitate slightly sometimes when going from 3rd to 4th. I'm suspecting my NSS is out of adjustment or dirty though, as I rarely get reverse lights and I only do when wiggling the shifter a bit. I'm suspecting the NSS could cause some tcm confusion as well. I'll keep driving the jeep and update again in a few days to make sure this was actually the problem. If I feel like it I might put on the new TPS again just to be sure.

**UPDATE #2**

So driving the Jeep further since the swap back to the old TPS, I haven't encountered any of the previous problems I mentioned. It shifts smooth now and I always get 4th so I have no reason not to conclude the TPS as faulty out of the box, and I will have to take it with my dealer.

### SOLVED ###

Ok so almost a year since this started out bugging me... and further headscratching, I put it aside for a few months since I figured out with some help that it was probably not mechanical in the transmission but electrical.

THE ISSUE WAS INTEED RELATED TO THE NSS.

upon opening it and examining the contact points on the swively thingy from the NSS moving part, the "thingimmabobbers" as Bleepinjeep refers to them as, were not moving out of their sockets as they were supposed to. One of the two were completely stuck down there and didn't make contact at all.

We soaked it in a jar of gasoline for a day.. and adjusted it approproately to the input shaft on the transmission, made sure everything was right by checking the NSS adjustment (bleepinjeep had a video on that on youtube)- fired it up and wonders.

No more kicking out of 4th. No more weirdness where it keeps the lockup engaged despite the throttle being completely let off (yes the tps is new, and is mopar, and is adjusted) and i finally have reverselights. Adorable things here in the dark part of the northern hemisphere (Sweden.)

Safe Jeeping folks, I hope this post helped someone out there.

OIIIIIIIO

Thanks for getting back with the follow up news.
Too many times the solution to a problem is never shared and doesn't get added to the store of knowledge.

@lazyxj - Of course: It was that frustration from previous experiences that led me to put the closing answer here. Being involved in IT as a profession, scoping through dead-end threads, desperate for a solution to a problem on a daily basis - I know the frustration of an un-finished thread. :clap: