“Start/Stop Not Ready”??

[MojaveMat]

Hey guys, I just realized my Start/stop hasn’t been kicking on. No errors or anything, just saying “Not Ready”. I’m in Michigan and it’s starting to get colder. Someone said there’s like 22 conditions for it to work. Anyone have that list available? I kind of like that it’s not coming on right now but want to make sure nothing is wrong. It was working annoyingly fine during the summer.

I read that it’s been the battery issue in early models but it would say “Battery Charging” or something. I’m seeing “Heating/Cooling”, “Engine temp not high enough”, then it goes to “Not Ready” and never gets into “Ready” state.

Any thoughts?

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[ATLTiger]

Had the same issue and it was both batteries. I would get them checked.

 

[Jeeperjamie]

I had the same issue happening, ended up being my big battery. Had the big battery tested at AutoZone and they said it was good. I took mine to the dealership expecting them to say it was the small battery that was bad. They said more times than not once they hook their machine up it normally shows the Big battery being the issue and they were right. Big battery showed a dead cell and wasn't charging well enough to keep the small battery charged. I had the big battery replaced and after 50 miles of driving the ESS kicked in and started working again.

For reference the ESS had not worked for about 6 to 8 weeks prior and the reason I had to get it replaced was I came out and my jeep was dead one morning and I had to jump it off.

Whatever machine they use at Hendricks is far more advanced than the OBD or whatever they check them with at your local parts store and don't rely on a voltage meter either because mine was showing 12.4 volts and was 100% my problem. Those small batteries are supposed to last a while from what I've been told. I got buddies that have over 100,000 miles and 5+ yrs on their small batteries in their JLs.

 

[Lunentucker]

The common issue seems to be that the aux battery is dying and when it does that it drains the main battery due to how they're connected.
There are numerous threads on how to break the connection or circumvent it to jump start.
Also wondering if temperature extremes are playing a role. I know ESS will not function outside of certain temperature parameters but I don't believe that it displays a message in that case.

Easy and quick is to pull fuse F42 and disconnect the negative cable from the AUX battery. Which cable that is depends on when the vehicle was made. They seemed to switched them around mid 2021.

 

[Lunentucker]

https://www.jeepgladiatorforum.com/forum/threads/jumperless-aux-battery-pcr-bypass.59836/

 

[MojaveMat]

I had the same issue happening, ended up being my big battery. Had the big battery tested at AutoZone and they said it was good. I took mine to the dealership expecting them to say it was the small battery that was bad. They said more times than not once they hook their machine up it normally shows the Big battery being the issue and they were right. Big battery showed a dead cell and wasn't charging well enough to keep the small battery charged. I had the big battery replaced and after 50 miles of driving the ESS kicked in and started working again.

For reference the ESS had not worked for about 6 to 8 weeks prior and the reason I had to get it replaced was I came out and my jeep was dead one morning and I had to jump it off.

Whatever machine they use at Hendricks is far more advanced than the OBD or whatever they check them with at your local parts store and don't rely on a voltage meter either because mine was showing 12.4 volts and was 100% my problem. Those small batteries are supposed to last a while from what I've been told. I got buddies that have over 100,000 miles and 5+ yrs on their small batteries in their JLs.

So it didn’t show up with a Battery warning on the Start/Stop gauge? Mine just says “Start/Stop Not Ready”. It’s a 21 Mojave…I bought it used with 8k miles but this is my first winter with it and I read cold can affect ESS.

 

[MojaveMat]

The common issue seems to be that the aux battery is dying and when it does that it drains the main battery due to how they're connected.
There are numerous threads on how to break the connection or circumvent it to jump start.
Also wondering if temperature extremes are playing a role. I know ESS will not function outside of certain temperature parameters but I don't believe that it displays a message in that case.

Easy and quick is to pull fuse F42 and disconnect the negative cable from the AUX battery. Which cable that is depends on when the vehicle was made. They seemed to switched them around mid 2021.

It’s been < 40 degrees out the last month so I’m hoping thats it. Will there be a warning message on the display if the smaller battery was having an issue? I have a 21 Mojave bought it used in the summer with 8k miles; hope battery would have already went if it was going to go. Has there been a recall or anything on them? Does the dealership make it right?

 

[Bonanza]

Your aux battery is dead. Get ready to replace both!

 

[MojaveMat]

Your aux battery is dead. Get ready to replace both!

So there wouldn’t be any notification, warnings or errors if the Aux is dead? If it is dead, what setup is needed to prevent it from happening again, with an actual fix? What is causing the issue to begin with?

 

[Bonanza]

So there wouldn’t be any notification, warnings or errors if the Aux is dead? If it is dead, what setup is needed to prevent it from happening again, with an actual fix? What is causing the issue to begin with?

Nope. You'd think so, but no. The issue is the dead aux battery will kill off the main battery at impressive speed. Litebrite did a video on how to bypass it all with fuse trickery but it seemed to be more trouble than it's worth. Getting to the AUX battery through the fender liner is the easiest way, and I ordered a battery from Ebay. It's been working fine for a long time-- I think the stock batteries just really sucked.

 

[MojaveMat]

https://www.jeepgladiatorforum.com/forum/threads/jumperless-aux-battery-pcr-bypass.59836/

This is done just to get the main jumped?

Nope. You'd think so, but no. The issue is the dead aux battery will kill off the main battery at impressive speed. Litebrite did a video on how to bypass it all with fuse trickery but it seemed to be more trouble than it's worth. Getting to the AUX battery through the fender liner is the easiest way, and I ordered a battery from Ebay. It's been working fine for a long time-- I think the stock batteries just really sucked.

Man, that’s annoying. Ok, so if that’s what it is, new GOOD batteries should do the trick? It’s not like there is a systemic issue or anything and it’s just going to reoccur…just crappy batteries?

 

[Ted Striker]

So there wouldn’t be any notification, warnings or errors if the Aux is dead? If it is dead, what setup is needed to prevent it from happening again, with an actual fix? What is causing the issue to begin with?

Yes, you will get the Avengers light (A with a circle and arrow around it) which indicates that the auto start/stop has stopped working. When this happened on my 2021 Texas Trail, the Stop/Start not ready message was on for a few months, ESS stopped working and then I got the Avengers light on the dash. Took it to the dealership (under warranty at 21,000 miles) and they replaced the small Aux battery. ESS worked for about 2 days and then stopped working again and the Start/Stop Not Ready message is back, but with no Avengers light (yet). The whole system is a pile of junk and eats through batteries like Skittles.

 

[Jeeperjamie]

So it didn’t show up with a Battery warning on the Start/Stop gauge? Mine just says “Start/Stop Not Ready”. It’s a 21 Mojave…I bought it used with 8k miles but this is my first winter with it and I read cold can affect ESS.

No, and don't listen to the small battery being the issue hype. It's most likely the large battery has a dead cell from who knows what and is not charging the small battery properly. All the time people think it's always the small battery when 90% of the time it's the large battery. At least 3 people I know with JLs have replaced their large battery and are still rocking the small battery, 2 over 100,000 miles, 1 pushing 80,000.

Not saying anything bad about anyone but a lot of people do a internet Diagnosis and most just go off of what others have said in a forum. I may not be right either but I'd go to a dealership and let them put it on their machine and tell you. It was $86 at my dealership for them to tell me and then if I let them replace the Battery they take that fee off the total, it cost me $300 total for them to tell me what was wrong and replace the large battery. You got to decide what piece of mine is worth to you.

Replacing both batteries will fix the problem as well but probably isn't necessary. If it's still under the original 3yr 36,000 mile warranty they will replace the battery for free.

 

[Jeeperjamie]

Yes, you will get the Avengers light (A with a circle and arrow around it) which indicates that the auto start/stop has stopped working. When this happened on my 2021 Texas Trail, the Stop/Start not ready message was on for a few months, ESS stopped working and then I got the Avengers light on the dash. Took it to the dealership (under warranty at 21,000 miles) and they replaced the small Aux battery. ESS worked for about 2 days and then stopped working again and the Start/Stop Not Ready message is back, but with no Avengers light (yet). The whole system is a pile of junk and eats through batteries like Skittles.

That's because it was your big battery not the small battery more than likely. The big battery isn't charging the small battery properly.

 

[Gvsukids]

This is done just to get the main jumped?

Bypasses the little battery. Very easy to do.

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