Transmission issue

Gentlemen,

To start off the vehicle is a 1995 Cherokee Sport.

Now some background. I posted this over on cherokeeforum but have yet to solve the problem so I figured I'd come ask the folks over here.

I've adjusted the kickdown cable and that didn't fix it

I did a drain/fill today and put in 2 different TPS (one oem and one not oem) and the thing still can't figure out what gear it wants to be in.

As soon as I hit 3rd gear it'll go in to 4th shortly after then drop back down to 3rd and fluctuate between 3rd and 4th unless I keep the gas pedal fully depressed then it stays in 4th but that results in me going faster than I'd like to in this beast. Lol

It shifts from 3rd to 4th around 2500rpms then the rpms will drop to around 2000-2250 once it is in 4th. Then it'll downshift to 3rd almost instantly until the rpms hit 2500 again then back to 4th and right back down to third. It just repeats it endlessly. Hopefully that clarifies it a bit better. 

None of this started happening until I did my tune up (plugs, cap and rotor) but, as far as I know, none of that crap has anything to do with the transmission shifting improperly. It was perfect until the tune up so either I messed something up or it is just an unlucky coincidence.

lift tires gears?

Everything is stock on it for now.

3.55 I think is stock gearing for this.

Can this issue be caused by a vacuum leak?

Ground wire issue possibly. Dig up the AW4 all you want to know thread here. Look for the details on testing the 3 electric solenoids.. You could be mistaking a torque converter lock-unlock for a 3-4-3 shift, which would be a bad brake light switch (it also tells the TCU to lock/unlock the TC) or could be busted wire to the switch, or solenoid #3 going bad.

XJriot said:

Can this issue be caused by a vacuum leak?

Click to expand...

No, cruize control is the only part that uses vacuum.

Re: Re: Transmission issue

Ecomike said:

Ground wire issue possibly. Dig up the AW4 all you want to know thread here. Look for the details on testing the 3 electric solenoids.. You could be mistaking a torque converter lock-unlock for a 3-4-3 shift, which would be a bad brake light switch (it also tells the TCU to lock/unlock the TC) or could be busted wire to the switch, or solenoid #3 going bad.

Click to expand...

Thanks man. Ill read it all tomorrow and hopefully do some testing. Im hoping it is just a busted wire (fingers crossed). If any are on the passenger side of the motor then there is a good chance i bumped one while doing a tune up. :thumbup:

XJriot said:

Gentlemen,

To start off the vehicle is a 1995 Cherokee Sport.

Now some background. I posted this over on cherokeeforum but have yet to solve the problem so I figured I'd come ask the folks over here.

I've adjusted the kickdown cable and that didn't fix it

I did a drain/fill today and put in 2 different TPS (one oem and one not oem) and the thing still can't figure out what gear it wants to be in.

As soon as I hit 3rd gear it'll go in to 4th shortly after then drop back down to 3rd and fluctuate between 3rd and 4th unless I keep the gas pedal fully depressed then it stays in 4th but that results in me going faster than I'd like to in this beast. Lol

It shifts from 3rd to 4th around 2500rpms then the rpms will drop to around 2000-2250 once it is in 4th. Then it'll downshift to 3rd almost instantly until the rpms hit 2500 again then back to 4th and right back down to third. It just repeats it endlessly. Hopefully that clarifies it a bit better.

None of this started happening until I did my tune up (plugs, cap and rotor) but, as far as I know, none of that crap has anything to do with the transmission shifting improperly. It was perfect until the tune up so either I messed something up or it is just an unlucky coincidence.

Click to expand...

I wonder if you disturbed these connectors or the tCU ground at the engine dipstick tube stud.
Cruiser’s Trans Plug Refreshing

Over near the transmission dipstick tube are 2 rather large connectors. One is black and the other gray. These 2 connectors carry all the info between TPS, TCU, NSS, speed sensor, and transmission solenoids.
Unplug each one, visually inspect for corrosion or bent pins, spray them out with electrical contact cleaner and plug them back in.
　
Additionally, if your Jeep is an 87 to 90 Renix, it’s always a good idea to reach up under the glovebox area and unplug the connector to the TCU and spray it out along with the receptacle of the TCU. While you’re there, find the fuse right in that area for the TCU. Remove it and spray out it’s receptacle and clean any corrosion from the fuse.
Revised 9-10-2012

Only the renix ones have the tcu under the glove box?

I think I know what connectors you're talking about. They're right by the #6 spark plug, right? I was fighting with them while getting the plug out so there's a very good chance I loosened up a connection. Assuming I'm talking about the correct plugs.

Correct on the location of the connectors. No, later years had the TCU under the glovebox, too.

Got it fixed. This is what I did.

1) When the PO took out the a/c and replaced the pulley with a delete they didn't reattach the ground that is in the front of the block on passenger side. It looks like they just put it on the bolt but never put a nut on it so while I was in there it came loose.

2) Cleaned IAC connector, TPS connector and those two that cruiser told me about with contact cleaner.

Thanks for the suggestions gentlemen. :thumbup:

I love happy endings. Great job at sticking with it!!