Transmission skipping 2nd gear twice on 42RLE

[stevenmcgurk222]

Hey all- I read about this issue happening on other 04-06 LJs with the 42RLE. When I drive, the transmission seems to skip second gear and the car jolts 1 to 3 times every time I turn the car on and gas. As I drive, it smoothes out phenomenally and the issue is forgotten, of course until I turn off the car and turn it back on.. This happened on the 29th day of my warranty and the (third party) dealer said it wasn't broken and needs a PCM flash; now out of warranty. Which is what led me to these forums and reading about the other LJs having the issue.

This all started happening after the dealership changed the alternator. Im guessing they somehow reset the PCM when they installed the alternator. they think it is still in "learn mode".
per other posts, it needs a flash or reset to stop from happening.
I took my car to local Jeep dealership who said they cannot help me because they no longer have a functioning
DRB-3 tool, nor do most dealerships as Jeep no longer supplies them.

What the heck do I do from here?
Will driving like this damage my transmission?
If I manually reset the pcm with instructions per Jeep, what is the protocol to help teach your PCM learn the "right way" of how to not skip on a gear?

I am reading online to never reset PCM yet this seem malfunction is worrying me as trannys aren't cheap... unless you're in Thailand.

Advice MUCH appreciated as this car has been mine for only 5 weeks

 

[Jerry Bransford]

There are software bugs in the transmission controller that is part of the PCM (engine computer). No guarantees but it's quite possible your problems are caused by nothing more than that... which is fixable if they're caused by those software bugs. Give Mark a call at www.wranglerfix.com and he'll be able to tell by talking with you if it's possible their reprogrammed PCM will fix it. They have a great reputation.

 

[stevenmcgurk222]

There are software bugs in the transmission controller that is part of the PCM (engine computer). No guarantees but it's quite possible your problems are caused by nothing more than that... which is fixable if they're caused by those software bugs. Give Mark a call at www.wranglerfix.com and he'll be able to tell by talking with you if it's possible their reprogrammed PCM will fix it. They have a great reputation.

Thanks- I agree that it is likely a bug. The shop I bought it from put in a new alternator and must've somehow brought the bug to life.

Do you think this is damaging the transmission and should be fixed immediately? Or is it something I just kind of have to monitor and if it gets worse and worse - act promptly? Definitely interested in replacing PCM and will call mike to discuss but already put about 1300 into repairs so trying to save a bit before I throw more and more money in

 

[Jerry Bransford]

As suggested above, call Mark. He's the expert on the issues, not me. It's a free call.

 

[stevenmcgurk222]

As suggested above, call Mark. He's the expert on the issues, not me. It's a free call.

let me know if you have advice on resetting the PCM. Im reading that it has frequently helped the PCM issue, yet I'm from my understanding its dangerous to remove just the positive wire (especially first) so I'm confused how people are resetting it per Jeep instructions

 

[Jerry Bransford]

let me know if you have advice on resetting the PCM. Im reading that it has frequently helped the PCM issue, yet I'm from my understanding its dangerous to remove just the positive wire (especially first) so I'm confused how people are resetting it per Jeep instructions

It won't help with your problem, at least not for very long, but resetting the PCM is easy... you can remove just the battery's negative connection and leave it disconnected for 10-15 minutes.

Or remove both battery connections and hold them together so they are touching to discharge the capacitors inside the PCM. Disconnecting the battery's negative lead does the same thing. it discharges the capacitors that hold the memory intact but it just takes a little longer.

If that technique worked to fix the bugs in the PCM Wranglerfix would not exist as a company.

You haven't called Mark yet? As said above, it's a free call and he can tell you if your issues are the ones his reprogrammed PCMs fix or not. And I'm not saying for sure one of his PCMs will fix your issue but at least you could have known if it would by now. After he asks you a few questions then he'll tell you if it will or not. Free call.

 

[THEREALJIM]

Hey all- I read about this issue happening on other 04-06 LJs with the 42RLE. When I drive, the transmission seems to skip second gear and the car jolts 1 to 3 times every time I turn the car on and gas. As I drive, it smoothes out phenomenally and the issue is forgotten, of course until I turn off the car and turn it back on.. This happened on the 29th day of my warranty and the (third party) dealer said it wasn't broken and needs a PCM flash; now out of warranty. Which is what led me to these forums and reading about the other LJs having the issue.

This all started happening after the dealership changed the alternator. Im guessing they somehow reset the PCM when they installed the alternator. they think it is still in "learn mode".
per other posts, it needs a flash or reset to stop from happening.
I took my car to local Jeep dealership who said they cannot help me because they no longer have a functioning
DRB-3 tool, nor do most dealerships as Jeep no longer supplies them.

What the heck do I do from here?
Will driving like this damage my transmission?
If I manually reset the pcm with instructions per Jeep, what is the protocol to help teach your PCM learn the "right way" of how to not skip on a gear?

I am reading online to never reset PCM yet this seem malfunction is worrying me as trannys aren't cheap... unless you're in Thailand.

Advice MUCH appreciated as this car has been mine for only 5 weeks

Wranglerfix's new PCM is probably going to be the solution. My 2006 LJR was doing the hard shift/skip last summer and it came back last month when the summer heat started up. Called Mark after finding the PCM solution thread on this forum and decided to order one. Very happy I got it, I've had it for about a week, put around 250 miles on it and its shifting great!

 

[stevenmcgurk222]

It won't help with your problem, at least not for very long, but resetting the PCM is easy... you can remove just the battery's negative connection and leave it disconnected for 10-15 minutes.

Or remove both battery connections and hold them together so they are touching to discharge the capacitors inside the PCM. Disconnecting the battery's negative lead does the same thing. it discharges the capacitors that hold the memory intact but it just takes a little longer.

If that technique worked to fix the bugs in the PCM Wranglerfix would not exist as a company.

You haven't called Mark yet? As said above, it's a free call and he can tell you if your issues are the ones his reprogrammed PCMs fix or not. And I'm not saying for sure one of his PCMs will fix your issue but at least you could have known if it would by now. After he asks you a few questions then he'll tell you if it will or not. Free call.

Spoke a little on chat but figured id try the "free" solution at least once. Local dealer found does a re-flash but that seems useless. Ive already spent a lot of money on repairs and replacements after owning the car six weeks. I will call mark after work one day thanks for the info

 

[AjRagno]

Erratic shifting can be caused by low fluid level. Try adding 1/2-1 qt. of ATF+4. I fill my 42RLE to the hot full mark on the dipstick. If you just bought this Jeep, it would also be a good idea to change the filter and add a drain plug to the pan.

The '05-'06 TJs use an NGC PCM. Simply disconnecting the battery clears long term adaptive memory. It can then take up to 50 warm up cycles/500 miles to restore long term adaptive memory.

There are two 42RLE quick relearn procedures you can perform without a scanner.

1. Start the engine (adaptive memory activates whenever there is a 40° rise in temperature so let it idle for a few minutes.)
2. Shift from Park to Drive (wait a few seconds)
3. Shift from Drive to Neutral (wait a few seconds)
4. Shift from Neutral to Drive (wait a few seconds)
5. Quick Learn Procedure Complete. Move Shift lever to Park or go for a drive

Performing the above allows the shift solenoids to determine how much pressure is necessary to hold the clutches.

In addition to the above, I also follow a quick learn driving procedure whenever I've had the battery disconnected.

1. Accelerate to 55 MPH, turn on A/C and drive with steady throttle for 2 minutes
2. Apply light brake pressure and decelerate until the transmission performs the 3-2 downshift
3. Accelerate back up to 55 MPH and drive with steady throttle for 5 minutes
4. Allow the Jeep to coast to a complete stop
5. Done. Drive normally

The above has always been enough to make my transmission shift smoothly right away but I have also read technical bulletins that suggest repeating the 3-2 downshift up to 80 times.

I don't think your issue is PCM related. Even if I did, I would not recommend replacing the PCM without first troubleshooting and performing a thorough inspection of the wiring harness.

The shift solenoids inside the transmission determine when and how the transmission changes gears (shift quality). They receive battery power through a fuse and relay in the PDC. Any reduction or momentary loss of power to the shift solenoids due to poor/corroded connections or a wiring shorting to ground will cause problems.

 

[TerryD]

Ever since pulling the battery cable to reset the CEL that my scanner wouldn't, the first 1-2 shift of each drive is sluggish and seems to temporarily put the transmission in limp mode.

If I then manually shift through the gears after a stop it functions normally from that point on.

I'm going to attempt these fixes to see if any of them helps.