Auto Start/Stop issue continues even after aux battery replacement.

[JeepCares]

I've continued to have the same issue on my 2021 JLR with the auto start/stop unavailable message sporadically appearing. My JLR has 6k miles, I've taken it to the dealership for diagnostics multiple times, but they never found anything. Supposedly, my aux battery is working fine but they can't give an explanation as to why I keep getting the message. The dealership was very cooperative and conducted an Indepth testing of the aux battery. On the 10th attempt, they confirmed the aux battery failed. Great, they replaced the aux battery, and I was good to go. I disabled the auto start/stop feature on my drive home from the dealership, and the same message appeared again. I informed the dealership of the incident, and I will be returning the JLR to the dealership for a 3rd time within a week. My 36-month warranty ends in two weeks, I am concerned because the technicians are clueless as to the root cause.

I'm trying to throw a hail Mary before my warranty expires. Does any know if the dealership will resolve this problem even after the warranty expires if they don't fix it by then?

I could use Roger Staubach and Drew Pearson right about now.

Alfonso

Hi Alfonso,

Thank you for bringing this to our attention. Please send us a private message with your VIN, so we can connect you with a case manager who can provide support while your vehicle is at the dealership.

Blair
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[Kleiss1]

My, start/stop unavailable battery charging light has been on for weeks. Even after they replaced the Aux. battery.
2021 JLURD.

 

[58Willys]

My, start/stop unavailable battery charging light has been on for weeks. Even after they replaced the Aux. battery.
2021 JLURD.

See posts #4 & #10.

 

[Kleiss1]

They wouldn’t replace main because it tested ok.
I need to take it back.

 

[TeleJeep]

On my 2018 JLU Sahara 3.6 with ESS (not etorque) the original batteries (main and aux) were replaced under warranty back in 2020. Everything has worked great with Auto Stop-Start (seldom used since it's a six-speed manual, only goes into ESS when the shift is in Neutral and the clutch is released). I normally press the cancel button on the dash each time I start the Jeep. All the sudden I started getting "Service Auto-Stop-Start" warnings. I isolated the batteries and the main battery was fine and the auxiliary battery was bad. It only lasted three years. I replaced it (with another brand of battery) and it's working again without error messages and the stop-start feature for what it's worth is working again. I would hope these batteries would last more than three years! My JLUS isn't my daily driver and if I'm not driving it for a while, I put it on a battery tender (with the vehicle OFF, both batteries are in parallel).

 

[Lrahier]

Anyone have anything new on this ESS Battery Charging issue? I have a 2020 Rubicon and started getting the Start/Stop Not Ready, Battery charging issue. I took it to a shop and they said the aux battery was bad and replaced it. The system then worked, intermittently, a couple of times and now I just have the constant Start/Stop Not Ready, Battery Charging message again a the time. Now the shop is suggesting it might be a software upgrade and want to charge $200+ for a software diagnostic, and possible software upgrade. Has anyone had this recommendation and tried it?

 

[TeleJeep]

With the vehicle off, Did you try unplugging and reconnecting momentarily the battery current sensor (sandwiched between the negative cable strap and the negative battery post). Be careful, it’s a fragile little connector with two fine wires that go to the regulator electronics. There’s a release button or tab to release the connector. This worked for quite a while until my big battery started going bad as well. Eventually replacing both batteries fixed the issue for three years. Started having problems again and this time the auxiliary battery was definitely bad. It lasted three years (Mopar battery). My new one is an AC Delco.

 

[Coronado]

[QUOTE="CMTAZ, post:
Main battery or the IBS. On my 20 Willy's it was the main battery.
[/QUOTE]

Agree. Auto SS stopped working on my ‘21 diesel; both batteries replaced by dealer and IBS showed (only) 47% on new main. Tech knew, immediately, faulty IBS; sensor replaced, now reading to spec. Auto SS, everything else, works as-designed.

A lot of battery issues reported on forum; Intelligent Battery Sensor should be checked. Fragile sensor. And they fail.

 

[Mojofallen]

Your trouble is most likely the main battery. The Jeep auto start system starts giving error messages around 12.4v. 12.4 volts is a battery at half-life by most standards. Obviously, your dealer does not understand the system.

I suggest getting a new main battery from Walmart. They have a H7 AGM battery that is 850CCA with a 4 year warranty. The Mopar batteries are 200cca for the small battery and either 600CCa or 700CCA for the main (depending on your option package).

Put in the new battery, disconnect and insulate the negative cable to the aux battery, pull fuse F42. All of your truck's features with operate as normal. I addition to that, with one battery the trucks battery system will operate just like cars have for the last 75 years.

I load tested the main battery. I turned on the lights on for 2 minutes with the Jeep off. Afterwards, I checked the voltage, and it was at 12.65 volts. I'm dropping it off at the dealership today.

 

[andy29847]

I load tested the main battery. I turned on the lights on for 2 minutes with the Jeep off. Afterwards, I checked the voltage, and it was at 12.65 volts. I'm dropping it off at the dealership today.

That's not necessarily a good test. Batteries that have been recently charged can have a reading in the 13v + range. Normal practice is to let the battery sit for 24 hours to determine the actual charge. Good luck with your service. It took me 3 visits before the dealer replaced my main battery. Then he put in a lead acid battery (not AGM) and that was replaced 6 months later.

 

[Diesel_Pwr6.6]

I’ve read through the comments on this topic, searching for help. I don’t see anything similar, so I’ll revive the conversation…
We have a diesel powered JL that has been aux deleted; the battery is physically removed, positive rerouted to the main battery, ground is taped up, fuse 42 is pulled. Everything was working per normal expectations; no warning lights, ESS functional but disabled by an eliminator.
We took it in for the HPFP recall last month, then noticed when the eliminator didn’t turn the ESS off, I now have the aux warning light and a service ESS message. No CEL, and no stored or pending codes.
The main battery had some age on it, and didn’t pass battery testing, so I replaced it with an EverStart AGM H7. Good battery, but still have the problem.
Today I swapped the IBS with our other JL, and it didn’t fix it. The other JL has no problems with the suspect IBS either.
So obviously something else has gone awry. Since it’s giving me nothing to work with, I guess it’s going to the dealership since it’s still under warranty, unless anyone has seen any good troubleshooting steps for this POS system. I’d love to know what all inputs it’s looking at for ESS to be useable. I don’t care that it isn’t working, but am concerned that something is wrong to cause it.
I’ve gotten good at reinstalling the aux battery and reversing my delete in less than 30 minutes…

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