Hi all,
I have a 1998 cherokee. 4.0, AW4, 4 wheel drive.

About a month ago, my tranny started skipping 3rd gear when downshifting. It was fine one day, and screwed up the next.

It goes 1-2-3-4 fine when accelerating, but when I punch it to go up a hill or pass, it doesn't shift into 3rd when it usually would. I have to give it even more gas, and then it goes into 2nd. When I let off the gas to go back to 4th, it goes into 3rd for about half a second, and then to 4th.

I can sometimes get it to stay in 3rd by almost "feathering" the gas pedal, but it doesn't want to.

It almost feels like a tps but I just replaced that.

It will stay in 3rd gear if I have the shift selector in 3rd instead of drive.

I've replaced TPS, 1-2 and 3-4 shift solenoid, 2-3 shift solenoid, adjusted TV cable, drained and filled the tranny twice, and replaced the filter. I have NO idea what it could be!

When I did the filter, there were a few shards of metal on the magnets, and a lot of fine metal powder. I had the jeep in water up to the floorboards for about 5 minutes 4 months ago, but that seems unrelated. I didn't do anything to it when the problem started, it just randomly happened.

Also, my mpg is pretty low right now. <15... Idk if that's related.

I would really appreciate help! I am so stumped with this right now.

 

Anyone?

 

Anyone? I'm thinking that they could have given me a faulty tps. it feels like a dead spot in the throttle

 

Are you sure it is going into 2nd. It will sometimes unlock the converter in 4th then downshift into 3rd which feels like 2 shifts but it isn't.

 

no, it's definitely one shift. It goes straight from 4th to 2nd, and I know because like I said sometimes I can "feather" the gas pedal and get it to go into 3rd instead. Thanks for the reply though!

 

What brand TPS did you use for replacement? Were your symptoms exactly the same before you swapped the TPS?

Keep in mind that your XJ has a TCM (transmission control module) as well that is also in play here for controlling your transmission.

I would also freshen ALL electrical grounds, just to rule out a goofy electrical gremlin here. Unlikely, but electrons are funny things....

 

Duralast TPS. I swapped it because I couldn't leave 1st gear. After I swapped the tps, it shifted perfectly for about a month. This shifting problem started about a month after I put the new tps in.

I am going to look for a new tcm next week at a junkyard.

I have freshened all my grounds, new wires, cleaned, etc.

Thanks for the reply!

Is it possible to rule out faulty TPS, or is that known to happen?

 

If your transmission shifted perfectly for a month when you swapped out your TPS, then YES, it's absolutely possible that the issue is still with the TPS circuit. If a new part changes symptoms then it's most likely related. Cause and effect principle in play here.

You may want to replace your Duralast TPS with a genuine Mopar/Jeep throttle position sensor. The TPS and Crankshaft position sensors are sensors that I like to stick with Jeep replacements if at all possible for best reliability and mating with your engine management system. I would also get a can of electrical contact cleaner and spray clean the connector for the TPS.

Is your check engine light on or have you ever seen it? If so, use a scan tool or a code reader to pull codes and post them up here for further comment.

 

it's never shown a cel. I'll try to get a new duralast under warranty, and if that fixes it, consider getting a mopar replacement.
thanks!

 

Update: replaced TPS. Symptoms are exactly the same. SO now the ONLY things I can still replace are the TCU and the TC lockup solenoid. I don't think it's the solenoid. And my milage dropped to 13. Feels related.

 

I'm a BIiiiGG fan of checking and renewing grounds.

 

I am too. I've checked cleaned and refreshed all the ones I know about. Can you think of any off the top of your head that I should double check?

 

Update: Replaced TCU. No change is symptoms.
THis is really driving me crazy. What else can I replace???? What other grounds can I check?? What should I be looking at? Speed sensors are the only things I haven't replaced.

 

CRUISER'S MOSTLY RENIX TIPS

TRANSMISSION CONNECTOR REFRESHING

OCTOBER 30, 2015 SALAD 13 COMMENTS EDIT



Over near the transmission dipstick tube are 2 rather large connectors. One is black and goes to the NSS and the gray connector goes to the transmission itself
. 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 1-31-2016

 

Thanks for your reply! I've already refreshed all these connectors and put dielectric grease in them. I do not think a 98 XJ has a fuse to the TCU, but I am not sure. It is not listed in the pdc or the owner's manual.