Clutch overheat message after regear

[hephaestus]

2018 JLUR w/maual trans

I regeared from 4.10 to 4.88. (Rear axle only for now.)

In Jscan I have tried resetting all control units, resetting tire size, resetting gear ratio, resetting eeprom, and doing the clutch relearn procedure, getting it up into 6th gear almost immediately after doing so.

Within a few blocks of my driveway in 2wd, every time, no matter how many times I do this, I almost immediately get service start/stop, then my gear indicator on my dash turns to "--" and then I get a clutch overheat message and go into limp mode.

I've read a lot about this all over the internet and the above procedures are what everyone says fixes it, but it's not working for me. Any suggestions?

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[Gregj]

Try disconnecting both batteries for a few minutes, hook them back up and then do the 6th gear relearn procedure. A lot of the instructions just say restart all ECU’s but that won’t work. Done this a couple times and that is the only thing that works.
Gregj

 

[hephaestus]

Try disconnecting both batteries for a few minutes, hook them back up and then do the 6th gear relearn procedure. A lot of the instructions just say restart all ECU’s but that won’t work. Done this a couple times and that is the only thing that works.
Gregj

Thanks. That worked. I am going to post a more detailed procedure shortly ...

 

[hephaestus]

Some background: I'm pretty sure I deleted my aux battery a long time ago by disconnecting the negative at the main battery and pulling fuse J42, but I went ahead and fully removed it today just to be certain.


JScan's official documentation for gear changes reads:


"Tire size - Manual transmission: When changing tire size in a JL with a manual transmission it is necessary to follow the procedure below to avoid DTC P08A6 error. Restart the PCM (Power Control Module) by either disconnecting the battery (batteries) or using JScan > Restart all ECUs adaptation. Once reset, drive the Jeep so: Vehicle speed is 40-80mph, in 6th gear. Accelerator pedal position is more than 0.392 volts. Flywheel torque is >75 Nm. Drive like this for at least 20 seconds. Once the module reads all the data it will re-enable the all gear sensor performance diagnostic.


Axle ratio - Manual transmission: After changing the axle ratio on a JL with a manual transmission you may need to run the PCM - clutch replacement eeprom reset procedure to prevent the vehicle from entering limp mode."


I had seen several other references to being able to manually reset the PCM via JScan instead of disconnecting the batteries, and that is initially what I was doing. So my first attempt was just resetting the gear ratio and driving, which resulted in an immediate clutch overheat message. I then tried resetting the gear ratio again, tire size, and EEPROM, which didn't fix it either. Then I started reading about the 6th gear relearn, which was confusing because everything I read made it sound like there was an adaptation within JScan to do that, but there isn't. I'm still not sure which function actually triggers the 6th gear relearn — it's either resetting the EEPROM or resetting the control modules. But once I read all that, I tried the resets, EEPROM reset, tire size, and gear changes again, then went for a drive trying to get into 6th gear as fast as possible. That didn't help either.


I finally found a post that said both batteries needed to be disconnected and that manually resetting from within JScan will not work. That's when I decided that if I had to go as far as accessing the aux battery, I might as well permanently delete it. So I completely removed it along with its wiring, jumped J3 to the aux battery terminal, and tried again. Both batteries were disconnected for roughly 30 minutes during this process, so I'm not sure exactly how long they actually need to be disconnected. After reconnecting, I reset all the control modules from within JScan, reset the EEPROM, and took it for a drive getting to 6th gear as fast as possible. Note that I did not change tire size or gear ratio again, as both were already reporting correctly. I suspected that neither of those functions was what actually triggered the 6th gear relearn, so I felt a try without them was worth it. I could immediately tell the issue was resolved — the message had always popped up within a few blocks of driving, and this time I made it well past that point.


Summary — procedure that worked, in order:

1. Disconnect both batteries
2. Reconnect batteries (Or in my case, just the main battery now.)
3. Reset all modules via JScan
4. Reset EEPROM via JScan
5. Drive in 6th gear as soon as possible

This is the procedure that worked for me. Apparently there is some memory hole somewhere deep down in a module that isn't erased by just resetting all the modules with Jscan. Physically disconnecting both batteries was the key.

I'd still like to know whether it's the EEPROM reset or the control module reset that triggers the 6th gear relearn. (I suspect it's the eeprom.) There is also an Adaptations Reset menu in JScan that I suspect might have what's needed, but I'm not sure.



Side note: About six months ago, when I first got this Jeep, it had an open clutch recall. I took it to the dealer and 12 minutes after leaving I got a Service Transmission message on my dash. The Jeep spent the better part of that month going back and forth to the dealership before they finally got it resolved. Today, while removing the aux battery through the fender well, I noticed a Christmas tree pin was missing. I now believe the dealer went through this same learning curve to get that message to go away. I wish I had done more research, because I paid them for that and didn't get to drive my new-to-me Jeep much that first month. Knowing what I know now, I suspect that I could have handled it myself with JScan.

BMP Calibrations was who initially pointed me to the post about the batteries, and who made life-changing tune improvements to my Jeep, so I thank him for that help.

 

[hephaestus]

Thinking back, my clutch overheat message did not go away after resetting the control modules, only after resetting the eeprom, so it must be the eeprom that triggers the 6th gear relearn. As such, I wonder if resetting the modules is necessary at all? It seems like most people that are doing this are just trying everything to make the messages go away and not trying to evaluate what actually did it once the shotgun approach works.

 

[Gregj]

Once you get the hot clutch warning the only thing that will clear it is the eeprom reset, the 6th gear relearn procedure has been needed after tire size change and gear ratio change since the beginning.

I’ve had mine since early 2019, way before the whole clutch debacle. Before the recall if you didn’t do the 6th gear relearn you would get a stop start error and the A! Light in the dash.
Now you get the hot clutch warning too.
Gregj

 

[hephaestus]

Once you get the hot clutch warning the only thing that will clear it is the eeprom reset, the 6th gear relearn procedure has been needed after tire size change and gear ratio change since the beginning.

I’ve had mine since early 2019, way before the whole clutch debacle. Before the recall if you didn’t do the 6th gear relearn you would get a stop start error and the A! Light in the dash.
Now you get the hot clutch warning too.
Gregj

There is no 6th gear relearn procedure. There's only module reset and eeprom reset, one of which entails the 6th gear relearn. People constantly posting about the 6th gear relearn is what confused me so much.

 

[Gregj]

There is no option in JScan for the 6th gear relearn procedure, it’s just a function a manual transmission Jeep has to do after certain changes to the settings. TAZER has a description of it in their instructions but their procedure won’t work. I don’t know what it does but failing to complete it will set the stop/start error. Maybe @alphawolff can give some insight into what it is.
Gregj

 

[hephaestus]

There is no option in JScan for the 6th gear relearn procedure, it’s just a function a manual transmission Jeep has to do after certain changes to the settings. TAZER has a description of it in their instructions but their procedure won’t work. I don’t know what it does but failing to complete it will set the stop/start error. Maybe @alphawolff can give some insight into what it is.
Gregj

Where are you seeing that description? I see a link in their instructions that says to click to read more about it but the link is broken.

 

[hephaestus]

I think Summit Racing actually has a working link to Tazer's broken linked 6th gear relearn PDF:

https://static.summitracing.com/global/images/instructions/zau-ztzrjlm_nb.pdf

 

[bd100]

I regeared from 4.10 to 4.88. (Rear axle only for now.)

So the front axle is still 4.10?

 

[alphawolff]

There is no option in JScan for the 6th gear relearn procedure, it’s just a function a manual transmission Jeep has to do after certain changes to the settings. TAZER has a description of it in their instructions but their procedure won’t work. I don’t know what it does but failing to complete it will set the stop/start error. Maybe @alphawolff can give some insight into what it is.
Gregj

the craziest thing is i've never had to do anything other than the reset procedure with our scan tool. its very possible the aftermarket scanners just don't work properly? i don't know. maybe try alfa obd instead of jscan?

 

[eastern]

Where are you seeing that description? I see a link in their instructions that says to click to read more about it but the link is broken.

I think you are trying to link it to some sort of option in the tool, as if it is the option.
It is not an option, it is not something you can simply activate even at the dealer lvl (from what they told me )

If memory does not trick me, there was a TSB around 19A recall that specified this procedure, and that is how they referred to it, "6th gear relearn"
I always viewed it no different than PCM reset, leave car powerless long enough and it has to relearn how the engine should operate.


" are just trying everything to make the messages go away " - that is because it is not always a solution, and it turns into a frustration, and when your Jeep goes into a limp mode, and it is your daily, and your local dealer is a complete sack of garbage that tells you "we cant replicate it" and feeds you lies and shit just to get you out of their shop while you are dumping money on the rental, and 3 TSB later you are still getting "service transmission" and "clutch overheat" message, and local sack of shit dealer blames it on aftermarket tail lights, and then you dump 1.5 grand on aftermarket clutch just to find out what sort of shitfuckery you got yourself into with that garbage, and then aftermarket clutch company feeds your shit and excuses..... Yes, people are trying everything to make the messages go away and not trying to evaluate what actually did it once the shotgun approach works , or does not work.

... totally forgot to mention JeepCare clowns that waste your time by giving you false sense of hope like they can influence anything, when in reality they are just ... clowns that waste your time.

 

[Dyolfknip74]

So the front axle is still 4.10?

I assume they're not using 4wd. Lol

 

[bmpcamry09]

Thank you for posting this. Battery disconnect on both batteries seems to fix all sorts of bugs on these when the computers come back in line with each other.

I believe this same procedure needs to be done when 6MT units install a cloned ECU as well if they decide they want a spare ECU for tuning.

In my tech days WiTech gave an option for module alignment. I think it was called proxi alignment or something along those lines. It was required when updating modules and also when doing other odd things like EGR valve replacement after an EGR relearn. I saw it fix all kinds of random bugs before. @alphawolff help me out buddy I can’t remember what that’s called.

I’m actually getting WiTech at home so that I can dig on some stuff. Just waiting on my stuff to arrive. Account already set up. The subscription cost sucks but it’ll be worth it for doing local stuff.

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