Transmission can't make up its mind on what to do

Ok today My 97 Auto 4x4 4.0L was having issues. It seemed as though it couldn't decide if it wanted to be in overdrive or not. My XJ is on 33s with factory 3.55 gears and a corrected speedometer verified by GPS. Usually my Jeep kicks into what I can only assume is overdrive around 50 mph. Today when driving down the road on a nearly flat grade at 55 mph where it usually holds overdrive solid with no attempt to downshift, it kept kicking in and out of overdrive. My first thought was maybe it was the result of my Neutral Safety Switch since it has been giving me some trouble lately I thought maybe this was another side effect. I have read multiple write-ups on how to clean the NSS and I have been meaning to do it for a couple of years now because my backup lights rarely work but I have either been busy or had a more pressing issue to attend to on the old Jeep. My second thought was TPS but I thought if it was the TPS then the engine would run funny too right? TPS is an easy fix but I don't want to spend the cash on a new one and throw away a perfectly good one if that is not the issue. I have a voltmeter I could check it with I just don't know how to properly diagnose it. The engine seemed to be fine now erratic or funny issues other than RPM change from changes in the transmission. Finally my third thought was something else was up electronically with my transmission but I have no idea what would be next to consider in that department.

My Jeep is my daily driver and I have a 40 mile commute and a road trip to take in a few weeks and I am trying to get it in good shape to make that trip.

Any ideas?

Have you tried putting it in 3 instead of OD to keep it from "hunting"?

Is your tv cable adjusted properly?

Check to see if your transmission kickdown cable is adjusted correctly. It's the most forward cable on the throttle body.

Here's how to adjust it.

1. Turn ignition switch to Off position.
2. Fully retract cable plunger. Press cable button all the way down. Then push cable plunger inward (Fig. 29).
3. Rotate primary throttle lever to wide open throttle position (Fig. 30).
4. Hold primary throttle lever in wide open position and let cable plunger extend. Release lever when plunger is fully extended. Cable is now adjusted.

There's a button on top of the cable mechanism just behind the metal mounting bracket. The "plunger" is the plastic sleeve around the cable where the metal stranded core exits.


Or check it out here.


http://www.allpar.com/SUVs/jeep/cherokee-transmission.html

Check your brake switch. If it senses the brakes are applied, it will unlock the torque converter.

Always start troubleshooting with the cheap and easy stuff, and with common Cherokee issues. As suggested, check the brake switch, re-set the TV cable.

TEST the TPS. Clean and correctly adjust the NSS.

Finding the AW-4 Service and Diagnostics Manual is not difficult, and it has complete troubleshooting charts and testing procedures.


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TPS

You may have one or more of these Physical Symptoms:

1) The engine loses power and is stalling.
2) The engine will idle, but may die as soon as you press the gas pedal. When driving, it seems as if all power is gone.
3) Sometimes it feels as if the transmission is failed or isn't shifting properly, if at all. If you quickly jump on the gas you might be able to get the transmission to shift, but it won’t shift properly by itself. Shifting manually, the transmission goes through all the gears.

NOTE: The throttle position sensor is also DIRECTLY involved with transmission shifting characteristics. The TPS function should be verified early in the troubleshooting process, when a transmission issue is suspected.

TPS TEST

You should have 5 volts going into the Throttle Position Sensor (TPS). It is best to use an analog meter (not digital) to see if the transition from idle to WOT is smooth with no dead spots. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5 volts. At idle, TPS output voltage should be greater than .26 volts but less than .95 volts. Move the throttle and look for smooth meter response up to the 4.49 at WOT. The other wire will be the ground and should show no voltage.

Perform the test procedure again and wiggle and/or tap on the TPS while you watch the meter. If you notice any flat spots or abrupt changes in the meter readings, replace the TPS.


The TPS is sensitive to heat, moisture, and vibration, leading to the failure of some units. The sensor is a sealed unit and cannot be repaired only replaced.

Ok I changed the TPS and if I have time to clean the NSS tomorrow then I will do it as well but I went to adjust the Transmission cable and noticed the cable was frayed. The "guide cup" (only thing I could think to call it" was making it difficult for the cable to slide in and out. I popped it off the plunger and cut it off to allow the cable to slide in and out of the plunger more easily as the plunger has a wider opening. I had to cut away a few of the frayed strands to allow it to slide in and out without getting hung up. There is about 60% of the cable still left so I am going to ride it out for a while until I can find time to venture to the junkyard to find me another one unless a new one is only $30 which I highly doubt.

My only concern is do ya'll think it will last a little longer until I can get a new one? I have no idea how long it has been like this so I think it will be ok.

Actually it is about $30 for a Crown replacement, if this is the right part number.

http://www.oconeeoffroad.com/servlet/the-40463/Crown-Throttle-Control-Cable/Detail
http://www.jeep4x4center.com/accelerator-cable-52077578.html

I think Morris has the wrong pic and description, but the right number.

Sounds like the frayed cable could be the cause or just some of the problem. I just went through this problem last week and turned out to be a sticking pin and spring in my NSS. Took about an hr to clean it up! Everything work now. Even have reverse lights again.