cperk

I have a 96 Cherokee 4x4 with 207K miles on it. I am having some problems with the transmission.

She seems to only want to run in 3rd gear at highway speeds (55mph and up). When I go up a steep hill it will shift into overdrive and the tach drops to about 1500 rpm. Once I top the hill it shifts back down and the tach jumps to 2000 or a little higher. If I smash on the gas it will downshift to climb the hill but still wants run above 2000 rpm. On flat level ground it stays in 3rd but will occasionaly shift into overdrive and back out again for no reason. At speeds under 45mph it runs great at 1500 rpm and shifts fine.

First thing I did was replace the transmission fluid and filter. It didn't do anything to help but it needed to be done anyway so no harm no foul. After that I did a little reading and decided to swap out the throttle position sensor. Still no luck..

Any advice? Would it likely be the transmission control unit? There are no check engine lights to reference.

Thanks

AbsoluteAggressor

Have you adjusted the transmission cable on the throttle body? Like so:
http://www.allpar.com/SUVs/jeep/cher...nsmission.html

Quick easy fix.

cperk

Thanks for the link. I did reset the cable, and it did look like it was off a little, but no love from the Jeep. On the highway at 60mph it keeps shifting in and out of overdrive every few minutes.

Still seems to run fine under 45 or so when you wouldn't use overdrive anyway.

I have an overdrive solenoid coming in tomorrow. I'll throw that on and see if it helps at all. I really don't think the transmission is bad, but if you have any other advice I'm all ears.

I did come up with a name for the Jeep. Now I gotta see if I can get plates that read OL BSTRD, cause this thing hasn't made anything easy!

Thanks,
Chad

freegdr

when you adjusted the linkage did the rpm and speed range change any with the issue

freegdr

tyr adjusting it doing the same thing but have a friend open the throttle body by depressing the gas pedal to the floor instead of using the arm on throttle body simulates actual travel better

cperk

I tried it again using the gas pedal, it does make sense to do it that way, but it still didn't help. It still has all of the original problems. Runs great and shifts through the gears all the way up to overdrive. Then it will kick in and out of overdrive above 50mph. It does it less if I use cruise control but runs at about 2100 rpm instead of the usual 1500 ish.

If I push on the gas it will drop into overdrive and I have to really gun it to get it to downshift to gain speed. Doesn't seem dangerous but it's irritating.

Also, there are no error codes to help out. The check engine light does not even flicker. I did the key off and on to pull codes but all I got was 12 (start test) and 55 (end test).

freegdr

are you using cruise on flat level ground ? any movement of the gas pedal will cause od to kick in and out

cperk

I am doing test runs on the highway here. It is pretty flat and level. The jeep isn't trying to change speed at all. Just drops in and out on it's own.

Could the actual torque converter itself be bad. I am not that knowledgable on transmissions and I have no understanding at all on what the converter actually does or what the "lock" is doing. Only that it is not doing it correctly.

I have also checked the switch on the brake pedal and it is good and fully engaged.

I'm down to thinking tcu or solenoids.

freegdr

im a stick shift lover my self if i want in a certain gear i put it there...lol...i think i know where theres a helpful manual i have saved ill pm it to you might help

cperk

Thanks for the link. I'm looking through it now. Quick question - I replaced the tps a few days ago. A 96 model does not require adjustment right? Just plug and play? I didn't adjust it at all.

And if I don't get this figured out the next forum search will be how to swap this auto for a manual!

cperk

I should pick up my new overdrive solenoid today and I hope to get it installed this evening. I already paid for it so I may as well try it. I would like to pin check it but I have to drop the pan for that and if I am going to do that I may as well have the new part. Transmission fluid is too expensive to waste. And I am afraid that if the sloenoid is intermittent I may think it is good when it is not.

If that doesn't fix it she's going to the mechanic Thursday for proper diagnosis.

My local transmission specialist has a pretty good knowledge of Jeep and (after lecturing me about reading all this crap on the internet...I thought it was funny) assured me that he will tell me exactly what is wrong on Thursday. So far I like the guy.

His guess based on what I told him is that the transmission is fine but that it is most likely the solenoid going out. He said it is probably not the NSS or TCU. He did say the throttle control could cause it but I just changed that out.

Maybe I'll get lucky and get it fixed tonight. Not really a fan of luck though when it comes to wrenching. I don't mind throwing a few obvious parts at an obvious problem but eventually you gotta narrow the field a bit when the obvious doesn't get it done.

olrik_wonderer

This sounds really close to the same problem I have on my 96 GC Laredo AWD. It started off small, then got worse and the tranny shifting got crazy. I went to change the tranny fluid and found a governor body bolt in the pan. I put the bolt back in and retightened the 4 bolts, changed the fluid, and it worked just fine. 5 months later it is starting again. It's like it can't make up its mind to stay in OD or not. It just goes back and forth, and you have to give it gas to get it to stick, but when you let off, it starts jumping back and forth. It seems to happen around 48mph. I have changed the TPS sensor and that didn't help. From what I keep reading the cable trick doesn't look like it would help. And I saw your post about changing the solenoid. Just wondering if that seemed to fix your problem? Up for any other ideas as to how to fix this problem.

cruiser54

Wanna try something simple that takes 5 minutes?

Over near the trans dipstick tube are 2 squarish connectors. IIRC, one is black and the other gray. These connectors are the information superhighway between TCU, TPS, solenoids etc. Unplug them, spray them out with electronics cleaner, visually inspect the contacts, add dielectric grease and plug them back together.

olrik_wonderer

I will try the unplug and plug about 3 times in the morning before I go to work, and post about it when I get to work. I know some times that might work. It's just weird. Also after I changed the oil the engine started acting stupid. I would start it up, and then it would just die. It's tough to pump an EFI engine to keep it running. But one you keep it running after startup it does just fine. I did notice that when you rev it up to get the RPM's up to keep it running, it does hit a bogging spot. Like it's flooding, or not getting enough air. Just wierd that startup problem started just after an oil change saturday morning in the ghosting snow.

cruiser54

Spray the plugs out, too.