Chick-N-Picker

This is for my brother-in-laws 97 Grand Cherokee 5.2 Orvis 4x4. He got the jeep gave to him from my paw paw. When he got it it would sometimes slip in first gear when taking off from a stop.

He drained the fluid and put in all new fluid with a filter. It fixed the problem completely.
He then had to park the jeep for a waterpump issues. We fixed all that.

So he thinks its time to drive his fixed jeep. We get in and the thing will not go in gear. Then it does but it's slipping and jumping to the max. We drive it maybe 1/4 mile and back but it's we barely made it. I said dude check the teams fluid first. It was bone dry, even though he put all fresh fluid.

so we fill it and he ended up having a split hose. We fixed that. So it's once again full with no leaks. We were hoping for the best.

we get in and now it will go but only in first gear. It will not change to any other gear.

I was going to unplug the TCU like on a regular Cherokee (what I drive) to see if it was electrical or mechanical. But where is the TCU located on a 97 GC, so I can check it manually? Can I even do that on this?

Also could him driving it 1/4 mile with no fluid have made it go into limp mode? What would be the way to reset that?

I just need help to help him? He has had this jeep since last May and has not drive it more than a couple weeks. He's about at his end. I wish it was a regular cherokee because i know way more. Thank you.

tony270

IMO and I don't know the mileage but when the transmission first slipped it was time to have it service or rebuilt, do I do that, no, I drive it until the wheels fall off, j/k. What I do is adjust the bands (2 adjustments on the 518, 1 on the side of the trans, and 1 inside the pan. And I would make sure that the detent (kickdown) cable was adjusted, returning, and working properly. Then I would add some Lucus Transmisson Conditioner (anti slip type). If that didn't give me a few more months I would say it is time for a remanufactured transmisson.

The biggest mistake was to let it sit, when an old transmisson sits valves, *****, and slides stick in the valve body, fulid passages get blocked, seals dry out, and hoses fail, sorry for the bad news.

tony270

The TCM is located left side (drivers side), engine compartment, very front above the finder well mounted on the side, opposite side the fuse box and battery. I wouldn't fool with it. Here's how I master reset the system:

a. Take off the positive battery terminal.
b. Then for 30 seconds ground the positive terminal to the negative terminal, this will drain any energy left in any capacitors.
c. Put the positive terminal back onto the battery post.
d. Move the key to the run position.
e. Switch on the headlights.
f. Switch off the headlights.
g. Switch the key off.

That should reset everything back to the factory settings and for the next 50 start up warming times will re-learn the motor, operating habits, the road conditions and any new parts.

Chick-N-Picker

it has 140,000 miles. yeah I know letting a vehicle sit can be bad but he had no other choice. Ok we will look into that.

I have a regular 89 4x4 cherokee with 86,000 miles, so it obviously did some sitting over the years, I can go back in time and drive it a little more each year but I just hope it keeps trucking along.

Chick-N-Picker

We will most certainly do that reset tomorrow. But I know on a regular cherokee you can unplug the TCU and switch gears manually.

Doing that will help you narrow it down. If it runs fine unplugged the you know it's electrical, sensor, etc. If it still isn't right then you know it's mechanical and in the trans it self.

I used this to help figure out a problem on my cherokee. It would shudder roughly at speeds only above 45mph. I unplugged TCU and it shifted and ran smooth at all speeds. So I knew the trans was fine. It turns out my brake light switch was sticking. Which causes the torque converter to kick in at , you guessed it, 45 mph. I loosened it up and plugged TCU back in and all was fixed.

I was hoping we could unplug TCU and use this idea to help us eliminate a few things.

tony270

A little more:
The blue arrow is pointing to the TCM, the red dot is the connection plug, the orange dot is the lock that needs to be lifted up to unlock the plug. Also some jeepers swear that the torque converter drain back check valve fails to open, or doesn't open completely, or debris restricts the fulid flow killing the transmission. Some cut the check valve out and splice it back together. Then before taking off they let the vehicle run in natural a minute or so to fill any fulid that may have drained from the torque converter and back into the trans pan. I don't recommend that, I bought a new lower radiator inlet trans cooler line "torque converter drain back line". I saw several modified lines on jeeps at the junkyard that had this modification.

When I bought my remanufactured trans replacing that line was required to validate the warranty. The red dots are the lower radiator drain back line, the yellow is the upper. In the last picture the red arrow points to the TCM and the yellow arrow points to the cooler lines. Don't fool with JC Whitney.

Chick-N-Picker

First thank you, but his jeep does not have that box and plug in there. I guess the 97 5.2 don't have them. I would like to try the TCU trick if at all possible.

Chick-N-Picker

Ok. It came to me. I didn't need to unplug his TCU. I just took out the trans relay under the hood.
Got in and it shifts pretty much perfect through the gears.

So it apparently isn't the transmission.

I'm thinking its 1 of 4 things.
1. Solienoid(s)
2. Bad TPS
3. Bad PCM
4. A bare wire or some other wire problem

I reckon I'll start doing research on checking Solienoids and TPS. If I can't find how I'll cone back and ask specifically.

Any other suggestions?