Transmission Shudder (2004 LJ Automatic 42RLE)

[Imposter71]

Hello All,

Fall of 2022 I picked up a used LJ Auto. Previous owner(s) had made some changes. It has 35s on 17 " JK(?) wheels, body lift, metal cloak fenders, different front bumper,etc. The list goes on but for the purpose of this thread I'm thinking the 35's are the more imprtantant info. I don't know if it had been regeared and the last owner didn't know either. Anyway from day 1 it had a little bit of a funny shift to it when it went into the higher gear(s). I generally have run it mainly with the overdrive off and it has been ok until lately. It developed a shudder when it shifts up. 1st & 2nd still seem OK but after that is usually when it happens. Fluid was a little low so I topped it off with ATF+4. The issue continued and got worse over time. Last week I had the fluid and filter changed. Refilled with ATF+4 and added shudder fix/additive- that from what I have, read may or may not help. It is maybe doing a little better but still not right. I only have about 50 miles on it so far since the fluid change. I intend to give it a little time, maybe a tank of gas/couple hundred miles and see what happens. I don't wheel it. It was bought and is used for going to the beach, a little beach driving, and running around town. I would eventually like to use it for some mild trails or some portions of the Trans America Trail ( TAT) if I can get it dependable enough to make some trips like that.

I like the jeep, plan on keeping it, and bought it knowing it would need work. It is worth it to me to fix it so I started this thread to chronicle the issue and what I end up going through to resolve it. The goal being to: 1) fixing it as cost effectively as possible and learn something along the way, and 2)maybe help someone else out with a similar problem with this information and results.

As always, any info/advice/suggestions are appreciated. Pic of the jeep added so you know what I'm working with.

 

[LONGJP2]

I like the jeep, plan on keeping it, and bought it knowing it would need work. It is worth it to me to fix it so I started this thread to chronicle the issue and what I end up going through to resolve it. The goal being to: 1) fixing it as cost effectively as possible and learn something along the way, and 2)maybe help someone else out with a similar problem with this information and results.

As always, any info/advice/suggestions are appreciated. Pic of the jeep added so you know what I'm working with.

I had a shudder and torque converter slipping issues going on.
Intermittent at first, but it got worse.
Ended up having it rebuilt.
If you add a gauge, you'll probably realize you need a cooler. (If you don't already have on.)

 

[Mike_H]

Any time I hear about transmission issues and LJ’s I think about the PCM problems. Since yours is an 04, they are far less common to have issues, but still worth getting the thing checked out. Talk with WranglerFix. Might not be the issue, but I’d hate to see you rebuild the transmission and that not be the issue.

 

[TexasTJ2004]

Any time I hear about transmission issues and LJ’s I think about the PCM problems. Since yours is an 04, they are far less common to have issues, but still worth getting the thing checked out. Talk with WranglerFix. Might not be the issue, but I’d hate to see you rebuild the transmission and that not be the issue.

WranglerFix deals with issues of 2005-2006, where TCM is integrated into PCM.

 

[Mike_H]

WranglerFix deals with issues of 2005-2006, where TCM is integrated into PCM.

They actually deal with ALL the different PCM's...He helped me reprogram my PCM when I swapped an auto into my manual Rubicon.

 

[TexasTJ2004]

They actually deal with ALL the different PCM's...He helped me reprogram my PCM when I swapped an auto into my manual Rubicon.

I knew that he is the way to go to address issues with PCM controlling 42RLE in 2005-2006.
In your case, Is that different from buying a PCM for Auto for your year?

 

[Mike_H]

I knew that he is the way to go to address issues with PCM controlling 42RLE in 2005-2006.
In your case, Is that different from buying a PCM for Auto for your year?

I wanted to keep my original PCM, since the VIN info was there and I knew it worked. So he re-programmed it from a manual to an auto. I had to buy a TCM from another source.

I know its not as common for the 03 and 04 Jeeps to have PCM / transmission related issues, but I wouldn't immediately cross it off the list, just because its not common, especially when looking at a 2500-3000 dollar rebuild cost.

 

[TexasTJ2004]

I wanted to keep my original PCM, since the VIN info was there and I knew it worked. So he re-programmed it from a manual to an auto. I had to buy a TCM from another source.

I know its not as common for the 03 and 04 Jeeps to have PCM / transmission related issues, but I wouldn't immediately cross it off the list, just because its not common, especially when looking at a 2500-3000 dollar rebuild cost.

I missed the part that you need to fix the VIN.
In 2003 to 2004 Auto, the TCM is a completely separate unit from PCM. It makes the decisions on shifting alone, taking some inputs from PCM, like the throttle position for example. Also, it seems be to be far more reliable that 2005-2006, at least by reading the forum here.

 

[AndyG]

On the outset I’m going to say that even for the best of shops they never really know until they get into the transmission everything that is going on-

It’s good to find out if you have a po740 code- This indicates your torque converter is not locking up/staying locked up within certain parameters.

When it gets down to it there are three big things with autos- Condition of the clutches, line pressure, and the operation of the torque converter-

Your real goal here is not diagnosis but to locate a really competent shop to help you through this.

 

[Imposter71]

Thank you for all the replies and suggestions. I've been working all week so likely won't get back to until the weekend. I only have 65 miles on it since the fluid/filter change. The CEL just came on too. LOL. I'll pull the codes and report back.

@LONGJP2 - I don't have a gauge on it but have wondered if that and a cooler would be a good idea anyway. I live in the Southeast, it is HOT here in the summer and the traffic is getting worse daily, so I am sitting as well as a decent amount os stop and go. That isn't even taking into condsideration driving in soft sand on the beach which is what I wanted it for in the first place.

 

[Imposter71]

Quick update.
Only up to about 90 miles since the fluid change. Drove it Thursday to run errands - seemed to work better. Went to go out a 2nd time and it revved up but didn't seem to move correctly, and I could smell something but not sure if it was brakes or something else. Got back to the house and both front wheels were hot to the touch so I may have some brake sticking going on as well. That was next on the list after the trans fluid change. Now I plan to do that next then continue with the tranny updates. I did pull codes on the CEL. Got the following
P0732: Gear 2 Incorrect ratio
P1775: Manufacturer Control?

I'll check back in as I go along. Hope everyone had a good 4th.

 

[hear]

The incorrect ratio code is possibly (likely) due to slipping. The input section is spinning at one speed and the computer expects the output speed to be a prescribed ratio relative to the input speed or else it throws the code. Could be several pressure related things, but it also could be burnt clutches. Air checking could rule out a few things.

 

[TexasTJ2004]

The P0732 is issued by the TCM when:
The input shaft (what comes from the torque converter) speed sensor and the output shaft (what goes out to transfer case) speed sensor ratios don’t match.
42RLE has the 2 speed sensors, located on the driver side of the transmission.
TCM knows that for example in the second gear, the ratio of speeds between input and output shafts needs to match the gear ratio. If it does not, you have slippage and that means usually that the gear is not working. Most likely the clutches are in the bad shape. The other option is that the oil pressure is not delivered to piston correctly, but that most likely would have caused additional errors.

 

[hear]

r/samepostonlylonger

 

[AndyG]

The first thing you may want to do is remove and clean the speed sensors it has been said they have a magnetic quality and can collect small particles

They are very easy to access

 

[Imposter71]

Thanks all. I have brake parts on the way now to take that sticky caliper issue out of the equation. I'll try to clean those speed sensors while I'm at it. Slow process due to work/life/toy balance. I'll keep posting updates as I go along.

 

[Imposter71]

Hope you all had a great Xmas and New Years. Hard to believe 6 months has gone by since I asked about this.

After a bit of a side track/starting/ground wire(s) rabbit hole that I ended up going down, I finally got around to the brakes. All that is done and we are back on the road again as of last weekend. I just reread this thread and it reminded me I still should look into cleaning the speed sensors, but it is running and driving. I have about 40-50 miles on it so far. Plan (like before) is to run a couple tanks of gas through it and see if that original fluid/filter change + additive helped at all. I find it hard to believe that will really do much, but since I have no way of knowing how well any previous owners mantained it, or if the right fluid was even in it, I felt it was a reasonable starting point.

It is really too early to tell much, but so far it is definately shifting better with less shudder. Fingers crossed and I will update again after I get some miles in it or when something else goes sideways, whichever comes first

Thanks again for all the input.