Any updates on this? I'm having what seems to be a similar problem.

I have a 93 Grand Cherokee with 190k on it and lately it's been bouncing in and out of overdrive constantly. The O/D on/off button has been going off and on with it but I can't manually force it to behave - even if I try to turn off the O/D it will eventually start acting up again. I have a feeling this is not something mechanical in the tranny, when I turn the jeep off and back on it seems to go away for a while (even if I just shut down for 10 seconds). All other shifting/driving is fine. Is there any way to permanently disable overdrive? Not a great solution but it would at least get me by for a while. Also, if this is a sensor (say TPS) what is the risk of just driving it this way for a while... just wear and tear on the tranny?

Thanks

 

I don't know if this would be much help to you guys, but I've tested my TPS on my 89 XJ by ohming out the two blue wires.

Basically, I placed a lead on the blue wire on each connector and actuated the throttle by hand. I think I read a range of 3-7 ohms. Basically, the resistance changed as I moved the throttle. I had a bad one that read open across the sensor. (no change, infinate ohms)

 

Hi everyone. I started this thread so I thought I should post what the final outcome was - BAD NSS.

To recap - At 65mph the RPM would jump from 2000 to 2400 or so. This would happen not just once while driving but was intermittent. Sometimes it would stay at 2400 other times it would bounce back and forth and many times it would not do it at all. I was told the jump in RPM's was the torque converter engaging and disengaging.

- I replaced the TPS with a dealer part with no positive effect.
- While testing I noticed that it the problem would reliably happen after driving for 45+ on a 60 degree night. So I thought it was heat related.
- At the same time my NSS no start problems were getting worse and finally ended up having to disconnect the NSS and jumper the pins to get it started.
- Tried a new NSS and it fixed both the starting issue and the torque converter engaging/disengaging problem. I had some shifting issues where the car would downshift while in D right after replacing the NSS. I realigned the NSS by putting it in R and lining up adjusting the NSS till the reverse lights came on. There is a little bit of adjustment one can still do while it is in R and the lights are still on. Adjusting it toward P versus toward "1-2" direction cured all the shifting issues.

So for those of you who are finding shifting issues. Try looking at your NSS. There are posts that say the NSS should not affect the shifting / torque converter issues but my experience has shown that it will.

Hope this helps some.

Thanks for all the help on the issues I have had with my car.

 

I think you should try putting some Lucas Oil Transmission Fix in it.

 

Here's a link on troubleshooting your transmission in the future.

AW4 TROUBLESHOOTING GUIDE
http://members.fortunecity.com/90limited/

 

The grounding on the NSS seems to have solved the problem. I have been testing it for years since it was intermittent I could not say if it was fixed either way.

 

I'm glad to hear that your issue has been resolved. However, you puzzle me with your presentation.

First message, I read, "Other than this the car runs great and has run great for ever. [sic]"

Next up, "At the same time my NSS no start problems were getting worse and finally ended up having to disconnect the NSS and jumper the pins to get it started."

Had you initially disclosed the NSS problems, this would have been an easy diagnosis to make.

 

This thread is 4 years old and I came back to report on an intermittent issue.

Sorry you were puzzled. I guess I have never run into a car that is at that time 13 years old, now close to 17 years old with at least something replaced, needing a cleaning, ... The NSS switch was brought up in posts slightly after the original post.


I think the above quote is from someone else. I searched and I did not see where I posted this.

That aside, I posted that I had NSS problems in the past in this thread but this post does not seem to be from me. Perhaps this is where you found the "presentation to be odd". Perhaps you where looking at a couple different posts at once.

Well, good to hear it would have been an easy diagnosis for you. The NSS past issues came up in this thread ... if you go back to read the whole thread.