Q&A and How-to: Jeep and Dodge Ram Automatic Transmissions

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Jeep/Chrysler 42RLE Troubleshooting and PDF Download

From: Roman L.

Sent: Thursday, September 06, 2012 12:11 AM
To: qanda@4WDmechanix.com
Subject: 42rle problem

I have an 06' Unlimited Rubicon with a 42rle and 57k. The problem is that before it reaches operating temp the tranny wants to stay in first gear regardless of where the selector lever is. Now if I continue to accelerate it won't shift till I reach nearly 3k rpm. When it finally shifts it clunks into second and the rest are smooth. I've tried letting it warm up but no change. Once driven for say 10-20 mins it won't act up as long as the jeep doesn't sit and have a chance to cool. I've read that a faulty O2 sensor or temp sensor in tranny could be the cause. I would like to use every part from sonnax in the tranny available just to make this tranny that much better. But like the saying "If it ain't broke". I recently got the tranny flushed since I bought the jeep with 53k thinking maybe it needed it. It didn't help. I also got a new mopar filter and a teakatoys tranny pan for extra cooling and fluid capacity. I am doubting that a new filter will help either. So should I upgrade everything possible with every sonnax part available and fix the problem? Should fix the problem and the rest till necessary? What is possibly going on and what should I do? Thanks

Roman L.

Roman, you’re on the right track, and Sonnax is the fix if you need it! They do have some trick stuff, and I follow their “cures” for better insight into trouble spots within a given transmission…The attached 42RLE transmission PDF is a combination of factory-level service data. These PDFs will help clarify the functions of the 42RLE. We’re not done yet, though, there's more to troubleshooting this unit!

Are you getting any PCM codes (Diagnostic Troubleshooting Codes or DTCs)?  The DRBIII dealership scan tool can interrogate the 42RLE electrical devices, this is a sophisticated tool that can simulate road conditions. 

Review the PDF material…Let’s keep working on this…

Moses

Further dialogue...

From: Roman L.

Sent: Thursday, September 06, 2012 10:37 AM
To: qanda@4WDmechanix.com
Subject: Re: 42rle problem

Awesome info. Thanks, I will get into this asap! Keeping you posted.

Roman L.

Roman…We need to explore the devices at play with the cold circuit.  On the 48RE (like my ’05 Ram), there are electrical circuits that override governor function when the transmission is cold. Typically, 50-degrees F of the transmission fluid is when the transmission goes to full governor function. There is interplay between the governor and solenoids in this process…We’ll see what gives with your 42RLE.

I’d rule out the oxy-sensor, since you have tried warming the engine completely before driving with no change in the transmission shift pattern. This tells us that the transmission is reacting to fluid temp in the transmission, not the engine or fuel-management temperature signals. We’re that far into the troubleshooting…

Moses

Noisy 32RH Like Tappets

From: Woody H.
Sent: Thursday, August 04, 2011 7:30 PM
To: qanda@4WDmechanix.com
Subject: 2000 Jeep TJ Trans noise
 
Greetings,
 
I have a 2000 Jeep Wrangler Sport 4.0 Liter/Auto Trans with 70,000 miles. Recently I have started to hear a noise that sounds like tappets but I feel it is coming from the transmission. I usually only hear this noise when the trans is warm and when the vehicle is out of Park. The noise accelerates if I increase the rpm of the engine as long the trans in not in park. I feel that this noise could be coming from the valve body in the trans. I also feel the engine is bogged down during the time I hear this rattle. If I let the vehicle sit with the engine off and cool, I can eventually start it up and do not hear the tappet noise. I would like your input on what my malfunction might be and what parts I should replace. The fluid level is normal in neutral when the engine is warm.
 
Thanks,
 
Woody

-----Original Message-----
From: 4WD Q & A
Sent: Aug 5, 2011 6:56 PM
To: 'Woody H.'
Subject: RE: 2000 Jeep TJ Trans noise

Hi, Woody, this is interesting.  Visualize that Park and Neutral as similar with two exceptions:  1) Park does not flow fluid to the converter while Neutral does, and 2) Park locks the output shaft and rear drum to the transmission case.  If this noise occurs in Neutral and not Park, I am suspect of the torque converter, or a rattling cooler check valve or a damaged transmission front pump bushing, each of which is more noticeable when fluid is hot and thin.
 
Since you suggest that the noise is like “tappets”, I would eliminate various sounds by using a stethoscope test tool, a sounding rod or a simple piece of conduit.  Probe each area and confirm the origins of the noise.  If you test the noise in Neutral, set the E-brake and chock the wheels as a safety measure.
 
If you find that the noise is local to the area of the torque converter housing, and that it disappears in Park but comes back in Neutral or the gears, it could be the front pump bushing or the torque converter itself. 
 
If you repair or rebuild your RH transmission, see my article in the Automatic Transmission Workshop on the RE/RH valve body upgrades to get fluid into the converter during Park engagement.  Your 2000 TJ is a prime candidate and vulnerable to front pump bushing failure, more prevalent when the vehicle parks for long periods or the cooling line check valve clogs or fails; this allows fluid drain back, starves the converter and front pump bushing in Park, and can cause pump bushing failure or damage.

Keep me posted, Woody.  Let’s follow this one through.
 
Moses

Woody adds info...

From: Woody H.

Sent: Saturday, August 06, 2011 8:16 AM
To: 4WD Q & A
Subject: RE: 2000 Jeep TJ Trans noise
 
Moses.... Thank you for your prompt and detailed reply..  I found the above article on your website and hope it is the one you are referencing.   

http://www.4wdmechanix.com/The-Automatic-Transmission-Workshop/Survival-Upgrades-for-Jeep-and-Dodge-Ram-Automatic-Transmissions.html

You did hit on one detail that is applicable to this vehicle as it is not driven frequently.  It used to be driven more when my wife and I were both working.
 
I did read your step by step workshop article on the rebuild of the RE/RH transmission.  I do know that my transmission is a 2000 three-speed automatic and it was serviced with fluid and filter at approx. 50000 miles.
 
My thought is to drain the radiator and replace with clean fluid and at the same time change the belts and hoses.  I am also considering adding a transmission cooler at that time.  The thought would be to see if I continue to get the noise after providing better cooling.   I have also considered adding a deeper pan on the transmission with extended fluid pickup to aid in keeping the transmission cool.   If these attempts fail I could then do an in chassis valve body upgrade as your article outlines.  The vehicle does not stick in park at this time and has not.
 
I would appreciate your opinion on what my thoughts are if you have time to reply.
 
Regards,
 
Woody
 
-----Original Message-----
From: 4WD Q & A
Sent: Aug 6, 2011 12:44 PM
To: 'Woody H.'
Subject: RE: 2000 Jeep TJ Trans noise

Woody, I’m good with all this unless the problem is the front pump bushing in the transmission or an actual defect in the converter.  Your upgrades each make sense.  The factory anti-drainback valve leaves a lot to be desired, that’s one of the reasons for the valve body upgrade.  Sonnax does recommend removing the OEM anti-drainback valve if you install the upgrade valves within the valve body.
 
Try to narrow down the noise to the converter/front pump area.  Also listen at the check valve for the cooler…Minimize the “parts replacement” approach and focus on curing the actual problem.  If the pump bushing or converter requires a repair, that’s close to a rebuild of your 32RH (assuming you have a 4.0L engine), as the transfer case and transmission must be removed to perform that service.
 
Regards,
 
Moses 
 
From: Woody H.

Sent: Saturday, August 06, 2011 9:56 AM
To: 4WD Q & A
Subject: RE: 2000 Jeep TJ Trans noise

Thanks Moses... and will do.... I wish I could make a recording of the noise for you.  I did hold my cell phone under the Jeep when it was making the noise and let a friend listen to it.  Does not sound like any bushing "bearing" noise I ever heard,  but if I had loose rocker arms "in my transmission"  (small joke) .... that is what is sounds like.   Only out of park and only when the ambient temp is warm or when I pulled that little trailer with my John Deere 318 loaded.   Once I heard the noise I shut it off, let everything cool.  Started it back up and drove home with no further noise.   I will keep you in the loop and I do thank you for your help.
 
Regards.... Woody

If you narrow the noise to the converter housing (definitely not the engine), this sounds like a converter shudder, cavitation or front pump clearance rattle…Try to narrow the noise location, Woody. A converter or front pump noise might be discernable at the transmission pan, as this is a harmonic member.

Moses

AW-4 Transmission 1-2 Shifting Quirk

Okay, Moses,

I have a 1997 Jeep Cherokee with this Toyota A304 tranny. Now these are very reliable, go about 350,000 miles or more, and best of all have a drain plug on the pan. But there is one thing it's always done, and I would like to find a fix, or maybe something is wrong with the rig.

Here's the situation, unlike this same tranny in a Toyota 4-Runner, the Jeep does not have an individual spot for manual 2nd on the selector. The low position is a combination of 1 and 2. It sometimes will just go to second when manual downshifting, and stay there, which is ok,
but sometimes it will go to first, and cycle on and off, no rhyme or reason to it.

The speed at which it downshifts to first can vary. It is the cycling back and forth from 1st to 2nd that's most annoying, so I don't usually bother downshifting the transmission on grades, I just ride the brakes, which is no good I know, but don't want the tranny shifting back and forth.

Any ideas? I looked into shift kits and did not see anything. Maybe as simple as popping the valve body off and removing a check ball, get it to have one or the other, manual 2nd or 1st,
depending on driver preference. Just seems like there is a hiccup in the Jeep with this Toyota tranny.

Frank

Hi, Frank...We commonly refer to this Jeep XJ Cherokee automatic as the AW-4 (Aisin-Warner). The shifting setup meets the Jeep requirements, and your problem narrows to a few possibilities. 

The 1-2 shift is controlled by the 1-2 shift valve. This valve is operated by the No. 2 valve body solenoid plus line pressure from the manual valve, the second coast modulator valve, plus the 2-3 shift valve. The transmission control module (TCM) deactivates the solenoid, which directs line pressure at the top of the valve to move the valve downward. This closes the second brake accumulator feed port.

Activating the solenoid opens a drain port. Spring force moves the valve upward, which exposes the brake feed port for the fluid to affect a shift to second gear.

There is also a Transmission Control Module (TCM) that interacts with the shift solenoids. Although this does not seem involved here, you can troubleshoot the TCM with a DRBIII scan tool or equivalent. The TCM stores codes, which can be cancelled by unplugging the "Trans" fuse in the module harness.

A transmission speed sensor on the output shaft is a longshot problem. This sensor sends signals to the TCM. Again, I would try simpler fixes before considering this component. Other shifts being okay, it is unlikely that the speed sensor is at fault.

Presumably, the transmission itself is intact without exceptional wear or loss of pressure. If you suspect that the valve body is full of debris, consider rebuilding it and testing the solenoids.

Since there are two prospects here, it would be wise to test the 1-2 solenoid first. If that tests okay, I would remove the valve body, disassemble it, then clean and reassemble.

As for shift modification kits, I agree that there should be one. Apparently, the low first gear ratio made the jump to second acceptable. (This works fine in low range!) I'm unaware of any means for using the Toyota valve body on this application, however, that might be worth exploring.

Let me know what you find!

Moses

Sharing a 45RFE/545RFE Shifting Solution

12 July 2011 06:27 PM

backwoodsgoop [Frank]

Moses, now I have got another one for you, the newer Jeep, Dodge tranny that I did not even know about, a 45/545RFE, can even be a 4 or 5-speed depending on configuration. So, I don't bother learning all these new trannys till they show up. This one tookme to school, a different shop pulled it out and called me up and said come get it, it's all loused up, slips , neutrals out, sounded like it was completely toasted.

So I tore it down, it is spin off of the 604 tranny in Dodge Caravans, and the A606, has a neat 3-gear pump, a regular metal clad filter for the cooler under the pan, but essentially a 604 Caravan tranny, inside. Was kinda happy to see that.

I dissassembled it and found nothing wrong, nothing, all looked about as good as when they stuck it together. Did some upgrades with a Transgo shift kit, a heavy duty accumulator cover upgrade, I read these stock ones can blow off, and also the same "converter drain back issue" you talked about. I called the shop to get a little more info of symptoms but they didn't drive it, said it was "So bad, didn't want to make it worse."

So stuck it all back together and they installed it, and did all the same things, but I knew I didn't find the problem, so that was no surprise.

So I went down and drove it back to my shop, here's what the thing did: just about no reverse, barely moved, delayed forward engagement, (with the scanner hooked up you could see it cycling back and forth and then engage, hard, then when driving it 1-2 shift was super hard, 2-3 shift neutral out for about 5 seconds then engage, hit 4th okay but no lock up.

And all of this without it going into limp in mode? It did go into limp once in all of my testing but that is it, consistently did all of this crazy stuff again with no internal problems in the tranny. So, I replaced the $400 solenoid block, that got the lock up working but all the same issues. No codes other than gear ratio error in R, but I knew that the thing would hardly back up. Oh, I almost forgot, the thing had reverse solid if you did get it in the limp in mode, so in the process of testing, I confirmed that it was not a mechanical or hydraulic issue, which was reassuring.

So long story short after replacing and fighting this tranny for a week, it turned out to be a line pressure sensor, bolted on the right rear of the case. All it said in the book was that it worked much like a throttle position sensor, and supplies the TCM/NGC with the line pressure information.

But without setting a code, this little bugger reeks havoc, makes you think that the whole tranny is loused. A little sensor that makes it seem like a mechanical failure and doesn't show up on the radar (scanner).

Frank

Reply from Moses...

Thanks for sharing, Frank. This sequence testing and conclusion is useful. Our 2002 Liberty had a trouble-free 45RFE four-speed overdrive automatic transmission. It uses a unique 2nd gear ratio for downshifting. The 545RFE is a 5-speed overdrive automatic transmission, used in the Jeep Liberty Common Rail Diesel models. The 42RLE is common in 2003.5 models and newer.

You can identify the 42RLE with its 13-bolt pan and straight crossmember. The 45RFE and 545RFE have 15-bolt pans and a rear-sloping crossmember. Models equipped with the 42RLE have a 4-pin connector and NGC PCM (Powertrain Control Module). They use an integrated TCM (Transmission Control Module). Models equipped with the 45RFE have a 3-connector JTEC PCM and a separate TCM.

Moses