42RLE transmission suddenly won’t shift

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2005 Liberty Limited 4WD/automatic with 189000 mi. Has been working perfectly then suddenly I get a transmission temperature warning and jeep goes into limp mode, so I pull off road to parking area now it won’t shift into any gears. Towed it home and pulled only a P0700 code with my OBD2 code reader, so I pulled transmission pan to check for debris. Trans oil looks great and there’s virtually nothing in the pan after rinsing everything With carb cleaner through a coffee filter, so I’m hoping it’s something simple like a speed sensor or a solenoid pack. Going to take it to a dealer for a full scan next. Anybody have any ideas what this could be?
 

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Leeann

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P0700 is just the general trans error code. You need a scantool (not just a reader) that can read trans codes to find the specific codes.
 
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Yep, that is the plan. I know the P0700 code is just a generic ****** fault indicator, so I figured the best approach was to start with a check of the fluid and look for any signs of a mechanical failure by examining any debris in the pan for iron bits that would stick to the magnet, or brass (bushings). If I had seen any of that, I'd just skip the trip to the dealership and buy a rebuilt transmission off of eBay or something. My oil and pan were pretty clean (I'd consider the small amount of debris I did see as just normal wear and tear), so I'm hoping that means my sudden no shifting condition is being caused by something electrical (a faulty sensor, wire, or connection), or something hydraulic (dirty solenoid pack, leaky O-Ring, etc.) In addition to reading the exact transmission codes that are triggering the P0700, the dealer can also use the pressure test ports on the side of the transmission to pinpoint the exact nature of the fault. I may still have to remove the transmission to fix the problem, but the repair is potentially much cheaper than buying a new transmission.

I'm not as familiar with the 42RLE transmission in the 2005, as I am with the 45RFE that's in the 2002-2003 Liberty's (since I had one of those for years), so I thought posting my symptoms to the JeepKJ community could be useful also. The 42RLE transmission is much "smarter" than the earlier 45RFE, in that it's transmission control module (TCM) is fully integrated with the car's power control module (PCM), so it can learn to shift, based on how you drive. I'll have to admit, I like the way it shifts, much better than the earlier 45RFE that's in a lot of Chrysler V8 trucks and the early Liberty's, even though the 45RFE is widely considered to be a "tougher" transmission, by the off road community. I know the 42RLE has it's roots in the early V6 powered mini-vans, but I don't know what it's common failure modes are now. Chrysler has sold a ton of V6 powered cars with similar versions of the 42RLE transmission, so I'd like to think massive production numbers and many years of engineering have created a pretty sound transmission. I do know that a fairly complete "rebuild" kit for the 42RLE can be had for around $250 that replaces all the common wear items, but if things like planetary gears or pumps are known problems, that would be good to know also. I've never had much success with automatic transmissions where major components like planetary gears were replaced.....
 

Leeann

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My ‘05 transmission went into limp mode when something inside the trans grenaded (before I got it). It only had 2nd gear.

However, it also went into limp mode after I swapped in a known-good transmission because I hadn’t replaced the 2 sensors on the driver’s side with Mopar sensors. Once I did that, the trans has been great for 70k miles (with a pan drop and filter change along the way).
 

runfor5

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^ the 2 sensors Leeann is referring to are the input and output speed sensors. I’d agree with replacing both of those at same time you change transmission fluid and filter. Use Mopar stuff for all of it just for peace of mind (sensors, fluid, filter). At that point you’d be about $150-200 into it at current prices, cheaper than a re-manufactured transmission. And the sensors can be swapped over anyhow if it comes to that.

5 quarts of Mopar ATF+4 ($50) and Mopar trans filter ($40) running $90 total right now on AMZN (I just bought last month).
 
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I finally have some time scheduled next week with a capable shop to read transmission specific codes. Will post what I find. I thought about replacing speed sensors first, but it looks like the front driveshaft has to come out to get access, so might as well wait....
 

runfor5

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I finally have some time scheduled next week with a capable shop to read transmission specific codes. Will post what I find. I thought about replacing speed sensors first, but it looks like the front driveshaft has to come out to get access, so might as well wait....
I’m real positive it does not (at least on my 2004). I had slippage after putting in a reman transmission myself and I distinctly remember replacing both sensors in my apartment parking lot without a jack or ramps at the time.

My issue there turned out to be the valve body but the reman company sent me a new one to install in there free of charge! I have an install post on here (swapping a 42RLE) if that helps and you got to the stage of replacing the trans yourself.
 

Leeann

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Yeah, the driveshaft doesn’t have to come out. I replaced the sensors after I’d driven the Jeep in the yard and I didn’t drop the driveshaft to do it.
 

TheRob

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Yep, that is the plan. I know the P0700 code is just a generic ****** fault indicator, so I figured the best approach was to start with a check of the fluid and look for any signs of a mechanical failure by examining any debris in the pan for iron bits that would stick to the magnet, or brass (bushings). If I had seen any of that, I'd just skip the trip to the dealership and buy a rebuilt transmission off of eBay or something. My oil and pan were pretty clean (I'd consider the small amount of debris I did see as just normal wear and tear), so I'm hoping that means my sudden no shifting condition is being caused by something electrical (a faulty sensor, wire, or connection), or something hydraulic (dirty solenoid pack, leaky O-Ring, etc.) In addition to reading the exact transmission codes that are triggering the P0700, the dealer can also use the pressure test ports on the side of the transmission to pinpoint the exact nature of the fault. I may still have to remove the transmission to fix the problem, but the repair is potentially much cheaper than buying a new transmission.

I'm not as familiar with the 42RLE transmission in the 2005, as I am with the 45RFE that's in the 2002-2003 Liberty's (since I had one of those for years), so I thought posting my symptoms to the JeepKJ community could be useful also. The 42RLE transmission is much "smarter" than the earlier 45RFE, in that it's transmission control module (TCM) is fully integrated with the car's power control module (PCM), so it can learn to shift, based on how you drive. I'll have to admit, I like the way it shifts, much better than the earlier 45RFE that's in a lot of Chrysler V8 trucks and the early Liberty's, even though the 45RFE is widely considered to be a "tougher" transmission, by the off road community. I know the 42RLE has it's roots in the early V6 powered mini-vans, but I don't know what it's common failure modes are now. Chrysler has sold a ton of V6 powered cars with similar versions of the 42RLE transmission, so I'd like to think massive production numbers and many years of engineering have created a pretty sound transmission. I do know that a fairly complete "rebuild" kit for the 42RLE can be had for around $250 that replaces all the common wear items, but if things like planetary gears or pumps are known problems, that would be good to know also. I've never had much success with automatic transmissions where major components like planetary gears were replaced.....
Im having the same problem 06 Liberty it shifts fine until it dosent shift. It downshifts but won't go in to any other gear after that comments suggestions insight please.... Oh if I shut it down then restart it's fine for a while then the same old song and dance again. I'm not a good dancer
 

runfor5

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@TheRob Do you have a CEL and codes? List them here it may assist ppl helping.

You said it works when you restart the car - does it work when you hit the OD button? Manually shift down to 1-2-D? Perhaps your solenoid is going bad. On the 42RLE (I have a 2004) thats tucked above or next too (can’t recall) the valve body and you could buy the Mopar one for like $300. Last I checked RockAuto awhile back at least.

Does your trans work okay when cold and then when it gets warm/at operating temperature is messes up? Parents have a older Yukon that did this - ended up needing a new transmission. Not saying that’s you, but I would start with dropping the trans oil pan and changing fluid + filter (use the Mopar stuff only for peace of mind). When was it last changed?

When you do that you can see if there is any odd debris/metal in the pan, and if the magnet on the pan has excessive metal shavings. You’d be surprised how much a fluid change can help these things. For $100 in fluid + filter + RTV/gasket and a bit of your time I’d give it a shot yourself.
 
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Got my Jeep back from the shop and the codes recovered from the Transmission Control Module (TCM) are "incorrect gear ratio 2nd gear and 4th gear". The transmission won't even turn in neutral with the engine shut down (meaning you can't push the car with the engine off and transmission in Neutral, unless you shift the transfer case into Neutral (its 4WD)). They are thinking that whatever caused the transmission to overheat (before it went into "limp" mode), probably welded the friction plates together on one or more clutches, and that's what triggered the incorrect gear ratio codes and is also causing the "locked up" condition. Since my transmission pan and filter were free of any iron debris, when I initially checked the oil, the shop believes the planetary gears are probably OK. Regardless, I've got to pull the transmission. I was hoping it was a sensor, a solenoid, something electrical, or valve body related, but they don't think that's the case after testing.

So.... next step is to pull the transmission myself and do a partial tear down to see if I can pinpoint the exact cause of the issue. I've watched enough YouTube videos of 42RLE transmission rebuilds, that I feel up to the task. So long as the planetary gears are OK, the next step will be to install a rebuild kit (consisting of new clutch linings, new O-rings and seals, new Solenoid pack, new torque converter, and general flush and clean). If the planetary gears are damaged, then my current transmission becomes a "core" trade in for a re-manufactured unit. I've never seen good results from local shops doing gear changes. Not saying it can't be done, but the times I've seen it done, the transmission was never quite right afterwards. They hummed, roared, shifted funny, etc. I think the gear setup process is pretty "tight tolerance" and requires very expensive setup jigs that most small shops are never going to invest in.

With the transmission out, I can also fix a leaking crankshaft main seal on the engine (it seems like every high miles 3.7 engine I've seen has a leaky main seal). If anybody has any "while you're in there" ideas of other things to fix/upgrade, please reply;)
 
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$hit. Turns out the planetary gears are toasted. I have a reman transmission in my future. I guess the lack of wear debris in the oil pan means it just suddenly let go. Jeep had 189000 pretty easy miles with regular maintenance. Kind of disappointing.....
 

runfor5

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$hit. Turns out the planetary gears are toasted. I have a reman transmission in my future. I guess the lack of wear debris in the oil pan means it just suddenly let go. Jeep had 189000 pretty easy miles with regular maintenance. Kind of disappointing.....
Dangggg oh no sorry to hear :/
Well if you don’t get yours specifically rebuilt, you could go Jasper or Street Smart. For me a few years back they were about the same price and idr why I went with Street Smart.

Their customer service was super good - the initial trans I got had a weird 2-1 downshift slip and they immediately offered to send me a new unit. I didn’t want to do the entire install over again so instead they sent me a new valve body. I would use them again. 40k+ miles and 1 fluid change since then and it’s done me good, knock on wood lol.
 
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While I’m waiting on a reman ******, I’m going to replace the transmission oil cooler and lines. I asked a mechanic at my local dealer about flushing the cooler and lines and he said they stopped doing it years ago. He said it never was effective on parallel flow coolers, so they just replace them and the lines now. Apparently they lost a lot of new transmissions due to debris in the oil cooler that didn’t come out using their flush machine and other dealers had similar complaints. Well that was their story, so I guess I can buy that, but the transmission cooler on a 2005 is a real PITA to remove. A flush would be a whole lot easier, even though costs of parts is about the same as they used to charge for flush services
 

Leeann

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My husband said there was no way to effectively clean a 2005 trans cooler while it was on the vehicle. So we removed it and cleaned it off the vehicle, which was effective. Pull it, turn it up on end, blast trans cooler flush from the top down and then the bottom up. Turn it over, do it again.

He’s an HVAC master, so he has a lot of experience with cleaning evaporators, coolers, etc. As I recall, it wasn’t that terrible to remove in order to clean.

The used trans I installed after cleaning the cooler and the lines has lasted for over 70,000 miles after cleaning the cooler properly.
 

runfor5

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Do your research online regarding the part # for the trans oil cooler. The one, at the time in ‘17, sold on RockAuto didn’t fit my 2004 with 42RLE. I had to buy it from the dealer (car had the factory option towing package) for about $235. The new cooler lines, also a dealer-only part, ran me about $75 I want to say. I can look up my part numbers on my Excel file just let me know.

The removal of the cooler was not particularly difficult that I recall. I had the radiator out too however, other work done at same time, so perhaps that was why idk.

If you can do the flush like Leeann pointed out then by all means! But IMO if you see metal at any point in the fluid there’s no way to definitely say it’s not elsewhere in the system. Also if you’re paying $1500+ for a reman transmission AND taking all the time to do yourself, why not spend another $300 and get it all square?
 
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New trans cooler and lines ordered. Took old one out yesterday and you’ve got to pull the radiator to get the trans cooler out. It’s easy if radiator is out, but that’s always a messy job. Put a new crankshaft main seal in while the trans is out. Also found and fixed a bad rear driveshaft U joint, front driveshaft CV and boot, and broken transfer case shift cable to lever bushing. Should have new transmission in this week. Have an appointment at my local dealer next week to run the quick learn process on the TCU with their DRB3 scan tool. It’s another $90, but no point in cheaping out now. I’ve read a few posts on this site from folks with first hand experience that a new transmission won’t shift right if you skip the quick learn and just let it learn on its own, after shorting the battery cables together to trick the TCU into a reset.
 

Leeann

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My husband pulled the cooler without removing the radiator. Then reinstalled it again without removing the radiator. I mean, he does this sort of stuff every day on a much larger scale (commercial HVAC), but it is possible.

I took my Liberty to the local Jeep dealer to have them do the quick learn after I got the transmission swapped. The ***** service writer ignored what I asked and they tried to upgrade the software on the TCU instead, which came back ‘latest software already installed.’ That’s not what I asked you to do, *****…

Make sure the ticket is written up right.
 
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Got the new transmission cooler today. It’s much bigger than the original one. 11 tubes vs 6, so I guess that will be extra cooling capacity, but I’m wondering if it makes sense to splice the outlet line from this cooler into the additional transmission cooler built into the radiator. The one in the radiator is currently not used, but on my Honda, it uses both a separate transmission cooler and the one in the radiator, plumbed in series. This setup is supposed to heat the oil up quicker and not let it get too cool for better fuel economy. The external cooler gives extra capacity for towing. I wonder why Jeep didn’t do something similar? Would that be a bad idea for a 42RLE transmission?

Regarding removal of the transmission cooler, it comes out without removing the radiator, but the lines don’t. You could raise the radiator a few inches, I suppose, but by the time you loosen everything to do that, you might as well remove it.
 

Leeann

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The lines do. I replaced them a few thousand miles ago, also without removing the radiator. Should have replaced them when I replaced the transmission, but I didn‘t. So I replaced them when I did the pan drop and filter change.

They were a little fiddly, but I didn’t even have to loosen the radiator mounts to swap them.
 
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