3.6L ESS Bad Aux Battery No Start Firmware Fix

Jebiruph

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When my 2018 JLU was at the dealers for the steering stabilizer recall, I asked about updating the radio firmware to fix some issues I was having (5" radio). They updated the PCM, ABS and radio firmware. Yesterday I noticed the low speed surging was gone, so today I tested starting with aux battery disconnected and it started.

Here's the write up for the firmware update.

jl firmware update.jpg


Before the update when I tried to start with the aux battery disconnected, the dash would continually cycle on and off and never try to start. I believe this is due to a starting process aux battery test that fails (dash off), then the process restarts (dash on) and this continues over and over as long as the button is pressed.

After the update when starting with the aux battery disconnected, the dash goes off one time and after it comes back on it starts. Then after it starts it shows a start/stop error. This is the same thing my 2020 JT does, the dash turns off once, then turns back on and starts.

It looks like the updated firmware is designed to only test the aux battery one time.





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jeepdabest

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When my 2018 JLU was at the dealers for the steering stabilizer recall, I asked about updating the radio firmware to fix some issues I was having (5" radio). They updated the PCM, ABS and radio firmware. Yesterday I noticed the low speed surging was gone, so today I tested starting with aux battery disconnected and it started.

Here's the write up for the firmware update.

jl firmware update.jpg


Before the update when I tried to start with the aux battery disconnected, the dash would continually cycle on and off and never try to start. I believe this is due to a starting process aux battery test that fails (dash off), then the process restarts (dash on) and this continues over and over as long as the button is pressed.

After the update when starting with the aux battery disconnected, the dash goes off one time and after it comes back on it starts. Then after it starts it shows a start/stop error. This is the same thing my 2020 JT does, the dash turns off once, then turns back on and starts.

It looks like the updated firmware is designed to only test the aux battery one time.
Did the 2019's and above already have this firmware? My 2019 starts with aux cable disconnected and throws a stop start error code.
 

Dkretden

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Did the 2019's and above already have this firmware? My 2019 starts with aux cable disconnected and throws a stop start error code.
I don’t know. However there is a thread here on this and it contains speculation that sometime during the 2019 MY, the ESS “logic” was changed. If true, some 2019 would have the new “logic” and all 2020’s
 

No IFS

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Good info. I have a early 19. Might be time for a software update
 
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Jebiruph

Jebiruph

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Did the 2019's and above already have this firmware? My 2019 starts with aux cable disconnected and throws a stop start error code.
I haven't seen any official announcement of a fix date, but so far I haven't seen anyone post that their 2019 didn't have the fix.
 

No IFS

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I have very early 19 build , first 3 days of production. If i try and test it by removing the neg aux battery cable and trying to start. Can it cause any codes or problems?
Thanks
 
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Jebiruph

Jebiruph

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Here's an update on mine. I was expecting the error to clear automatically after the aux battery was reconnected, but I had to use a scanner to clear it. ESS was disabled the whole time the error was active and I'm assuming the aux battery test was also disabled.

So evidently with the firmware update, the aux battery is tested every cold start and if it fails, the error status is set until manually cleared. With the error status set, the cold start aux battery test and ESS are disabled.
 
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Jebiruph

Jebiruph

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I have very early 19 build , first 3 days of production. If i try and test it by removing the neg aux battery cable and trying to start. Can it cause any codes or problems?
Thanks
You'll have to use a scanner to clear the error and ESS won't work until it's cleared.
 

jeepdabest

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You'll have to use a scanner to clear the error and ESS won't work until it's cleared.
Some have reported that disconnecting batteries for a few minutes will also clear the code but scanners are cheap on Amazon
 

No IFS

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Thanks for the info everyone. I don’t have a way to clear the codes right now so I’m not gonna experiment.
Would something like the J scan work to clear codes?
 

JeepCares

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Did the 2019's and above already have this firmware? My 2019 starts with aux cable disconnected and throws a stop start error code.
I have very early 19 build , first 3 days of production. If i try and test it by removing the neg aux battery cable and trying to start. Can it cause any codes or problems?
Thanks
Here's an update on mine. I was expecting the error to clear automatically after the aux battery was reconnected, but I had to use a scanner to clear it. ESS was disabled the whole time the error was active and I'm assuming the aux battery test was also disabled.

So evidently with the firmware update, the aux battery is tested every cold start and if it fails, the error status is set until manually cleared. With the error status set, the cold start aux battery test and ESS are disabled.
Hi all,
While we see that you are all reaching out to fellow forum members for support, we recommend visiting your dealer for software assistance. If you would like our additional support or if you have any questions, please do not hesitate to send our team a private message.

Kathryn
JeepCares
 

four low

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JeepCares, no offense, but the reason forum members are reaching out to each other, is that they are more knowledgeable than the Dealers, for the most part.
A continual complaint is that Dealers lack the ability to diagnose, and successfully repair our JLs, JTs.
More and Better Training would be a huge plus ; FCA will need to up its game , especially in light of the coming Bronco competition.
SERVICE CAN MAKE OR BREAK A BRAND...
Thank you.
 

multicam

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You'll have to use a scanner to clear the error and ESS won't work until it's cleared.

Sounds like you just discovered a free way to permanently disable ESS... I mean, aside from taking your doors off and putting them back on a few times, which can result in bent pins in the door wiring harness and all kinds of weird errors, including ESS being disabled.

I did get all the latest firmware updates when I brought my jeep in for the manual transmission work recently and I must say, I love the changes. It’s a lot less “surgey” when depressing the clutch; the RPMs just drop like they’re supposed to. Also, recirculate A/C stays on instead of just shutting itself off at highway speeds. There may have been other changes that I didn’t know about like this one that are also great.
 

jeepdabest

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Sounds like you just discovered a free way to permanently disable ESS... I mean, aside from taking your doors off and putting them back on a few times, which can result in bent pins in the door wiring harness and all kinds of weird errors, including ESS being disabled.

I did get all the latest firmware updates when I brought my jeep in for the manual transmission work recently and I must say, I love the changes. It’s a lot less “surgey” when depressing the clutch; the RPMs just drop like they’re supposed to. Also, recirculate A/C stays on instead of just shutting itself off at highway speeds. There may have been other changes that I didn’t know about like this one that are also great.
Did your dealer charge you for the firmware update?
 

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