ESS Broken After Regearing

[intentsrig]

Sorry i lol’d i said the same thing to myself

I think that was before my front axle haha

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[omnitonic]

I'm always a little skeptical about threads from years ago, as there have been several design changes along the way. It seems appropriate to share my results here. I have a '21 with the 3.6 and the 6MT that I just regeared to 4.56. I set the axle ratio with J-Scan right there in the shop parking lot, and I was surprised and dismayed to experience gremlins on the trip home.

As described here, every time I stopped and turned the engine off, everything would reset, but upon starting out, I wouldn't make it far before "Service Start Stop System" popped up, and my current gear indicator displayed " -- ." I didn't get a check engine light, but there were lots of weird transient codes. I cleared them, and they kept coming back.

I eventually hit on the idea of fully disconnecting the batteries (It's critical to separate the multiple pieces that are all attached to the negative battery terminal). The problem never reappeared, even though I drove for quite some time before I managed to get up to 6th gear.

I couldn't care less about the start stop system, but I really enjoy the current gear indicator. I'm relieved that it's working again.

 

[Az-jewel]

Thanks for the update! I vaguely recall Something about disconnecting the battery fully and then driving for 15 minutes at a speed (60?) to reset it. It’s been 2 years now. Glad it’s working well for you!!

 

[rlong69]

Yes, I just did my re-gear and used a Tazer to update the ratio. It does not matter how you update the software a complete power down appears to be the magic.

I do not believe there is any driving procedure etc that matters after, just the battery disconnect.

 

[jbcrane]

Big thanks to all who have contributed to this thread. It saved my ass today. Had new gears installed - Dana Spicer 4:88's in my Mopar-lifted 6-spd MT with 315/70/17's. After the initial lift a few months ago I successfully completed the re-learn procedure using the Tazer. This eliminated the ESS error in 5th & 6th and everything was fine.

When I got the Jeep back today after the 3:45 -> 4:88 gear swap it threw the same ESS error in random gears, at random speeds. Numerical gear indicator off, back-up camera/lights not working. Ugh, I thought... here we go again.

Went through the re-learn with the Tazer twice, unsuccessful. Discouraged... started snooping around and found this thread. Sure enough... disconnecting the negative(s) from battery and letting him sit a few minutes (5?), then reconnecting everything-fixed the issue. Went ahead with another (3rd) re-learn as per the instructions, for posterity. Everything's fine now. Mine is a '21 Sport S with M220 Rear (LSD) and M186 Front (open).

No words describe the difference in feel going from stock 3:45's to 4:88's. Power in every gear. First isn't too short - just right, in fact. Firmly believe it's how the Jeep should come out of the factory. Super happy. Thank you @Northridge4x4 for a job well done. You guys helped me. Anyone has any questions fire away.

 

[jbcrane]

I couldn't care less about the start stop system, but I really enjoy the current gear indicator. I'm relieved that it's working again.

Agreed. For the past year I've been driving him stock and knew his gears like the back of my hand - never really used the numerical read out. Now that I'm running a new ratio the numerical read out helps me re-learn what gear I'm in. It's that much different feeling from stock gears. Now when I'm in 6th gear it almost feels like it used to in 4th with the 3:45's. Incredible difference. How they should come from the factory stock, in my humble opinion.

 

[rizion]

Thanks for this thread! Had my 3.45s swapped to 4.88s last week and assumed the Tazer Mini would do the trick, but I couldn't get it to work. Had previously done the MT relearn when I went to 35s but the same process wouldn't get it done after the regear. Texted back and forth with Tazer and they let me know to do this, but I wasn't sure if I needed to dig down and disconnect at the Aux or not. So again, thanks for this thread. Disconnected at the main terminal and separated the two lines plus I unplugged the third small line with the clip. (Not sure if that was necessary but everything works as it should now). I let it sit disconnected for about 45 minutes this morning and I did get a little spark when I connected them back.

 

[SadRobot]

I just re-geared and came upon this thread. Just want to make sure I'm doing the correct thing. Pic below of my battery. So I need to disconnect all 4 of those wires, make sure they are separated, wait a bit, then hook back up? Do I kneed to disconnect the positive at all?

 

[Seer]

Hi Everyone,

I recently regeared my 2021 JL 2-Door sport manual to a 4.56 ratio, and I'm getting a "Service Transmission" error. I went to the shop and used my JScan to change the axle ratio. I also disconnected the battery cables and drove in limp mode to perform the 6th gear relearning procedure, but nothing changed.

When I got home, I disconnected all battery cables again, including the auxiliary battery under the fuse box, and waited about two hours, but I'm still seeing the same error.

Do I need to take it to the dealer for a reflash, or can I do it with JScan? My jeep is in limp mode right now so it is not really driveble for long distance.

PS: Had 19A recall for manuals 2 months ago (I wonder that recall change some software settings)

Thanks for your help!

 

[Seer]

Hi Everyone,

I wanted to follow up regarding the regearing issue that’s causing the "Service Transmission" message on the dashboard, which puts the Jeep into limp mode. I took it to the dealer, and they reflashed the ECU. However, there are still no error messages, and the "Service Transmission" warning remains, along with the limp mode.

The dealer is unsure of the next steps, so I’m reaching out to see if anyone affiliated with Jeep or in the mechanic community might have insights on this issue. Any advice or ideas would be greatly appreciated!

Thank you!

 

[Seer]

Hi Everyone,

I wanted to follow up regarding the regearing issue that’s causing the "Service Transmission" message on the dashboard, which puts the Jeep into limp mode. I took it to the dealer, and they reflashed the ECU. However, there are still no error messages, and the "Service Transmission" warning remains, along with the limp mode.

The dealer is unsure of the next steps, so I’m reaching out to see if anyone affiliated with Jeep or in the mechanic community might have insights on this issue. Any advice or ideas would be greatly appreciated!

Thank you!

HI Everyone,
this fixed my issue. For anyone who might have this problem after the recall 19A for manuals.
https://www.jlwranglerforums.com/fo...re-for-jl-jt-with-manual-transmission.128371/

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