ESS FAILURE

[LouisianaLady]

The ess on my 21 willy's sport ecodiesel stopped working about a year after ownership. No warning lights or messages. Took it to the dealership. They did a software update. Still didn't work. 12k mile later still No warning lights, messages or problems.

Mine worked for year also then died. Dealer
Charged and replaced auxillary twice. 5 different service trips for ESS battery issues.. ESS system on 2021 and earlier I expect all have substandard ESS system.2023 and 2024 now have torgue engines and cold air intakes that I bet help. Jeep servicemen say that torque engines work fine with ESS. Problem: ESS does not work with out automatic transmission. Thank you for your help.

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[richk225]

The ESS stopped working on my Wifes 2017 Grand Cherokee and it was a blessing, we both hated it. On my 2018 Rubicon JLUR I bypassed the ESS system by removing one of the wires of of the hood plunger switch near the drivers aide headlight. This was the non E torque engine with a regular starter and alternator with the towing package.
Did I hear you correctly, Jeep turned your money down to upgrade you battery and alternator? Plenty of info on this forum to do it yourself.
My 2021 like all 392`s does not have ESS but if it sits for a week or so the message comes uo on the dash stating that the AUX switches are disabled untio battery reaches proper charge or verbage close to that.
There are some on this and other forums who have chosen a deep cycle or a red or yellow Optima battery and removed the aux battery and ran it to the deep cycle battery, I don`t know enough to speak of it and there are some who have replaced the Jeep aux battery with a high amp motorcycle or racing battery

 

[STW]

Thanks STW. You are right. I live in New Orleans. Lots of slow traffic. Replaced my auxilliary twice. Combined charge must be 86% per dealer. Misdesigned aystem. I may just buy the main battery and have them charge both up to 86% No other choice but to consider having dealer replace this with new model with torque engine and 2024 models also have cold air intake. JEEP NO LONGER WILL SELL 6SP MANUAL TRANSMISSION SINCE ESS NEEDS POWER SYSTEMS INCLUDING POWER STEERING TO WORK. Getting bigger main and another aux and charging both up to 86% may work. If not, I will do the bypass. Problem: i spent 41k on car plus $3200 extended warranty and it's poorly designed with electical system substandard. They will replace but Jeep makes nothing I want now: automatics only. I will continue studying your email. THANK YOU.

One other suggestion that helps with the existing Main/Aux system is plugging into a charger every night. That keeps both batteries topped up, and can make the difference for someone who's had Main/Aux trouble and would like to keep it in place.

Easy enough for someone who parks in a garage, and may be useless suggestion for someone parking on the street.

It also helps to install an on-board charger. When my Main/Aux system first failed after I got it working again I was putting it on a charger nightly. But it's a pain to open the hood and clip leads to the terminal every day.

For the JL Main/Aux charging, use a higher amp charger than the usual trickle charger--Noco 10 is pretty effective for this, and some have found a 5amp charger to be inadequate for charging the Main/Aux system. I installed a Noco 10 in the jeep with battery leads in place, and installed an external plug-in outlet on the cowl. So it's very easy to plug it in and unplug it, coming and going.

I've never had to do something like this for any car I've had, and I don't have to do it anymore now that I bypassed the Aux, minimized ESS use, and got a new healthy Main battery. I think if I'd been charging it nightly like this, my Main/Aux system would not have gotten into trouble in the first place, even with lots of short trips and inadequate alternator charging. Because it would have started every day with a full charge.

 

[Bayrat]

Have 2021 Wrangler Rubicon manual transmission with ESS that doesn't work. Did work originally. Still in warranty and repair attempted by dealer 5 times without success. Broken ESS means bad mileage. 2024 Rubicon and Rubicon X have "cold air intake" which is new feature. Bigger problem is no 2024 Wrangler Rubicon with manual in existence anywhere in U. S. for me to test drive.
Car came with 650 amp battery and 220 amp alternator. Auxiliary is 12V. Dealer refused to sell me and install HD tow package which has 700 battery and 240 amp.
Any suggestion as to how I can come out of this headache getting best possible mileage on my car OR a new 2dr. Wrangler Rubicon with manual transmission with all working parts? Dealer will accommodate. Thanks.

My last Rubicon 2 door was a standard with the six, no SS. I never achieved the advertised mileage. The SS fuel savings is minuscule if any at all.

 

[LouisianaLady]

My last Rubicon 2 door was a standard with the six, no SS. I never achieved the advertised mileage. The SS fuel savings is minuscule if any at all.

My previous 2016 Rubicon 2 dr. with standard always got better than 17 MPG. That car had no power package however: crank windows, etc. AM FM Serious radio and auxiliary cable. Also had information system-- tire pressures, etc. Great!

 

[alphawolff]

Yes. It says "Not Ready Cabin Cooling or Heating". Says this 100% of the time. Live where its been 90-100° for 3 months but problem started October 2022. Also have "rag" top.

The ESS isn't going to activate because you're asking for AC at such at level that it'll never turn off. Stop using MAX A/C and you'll find it starts working again. It'll shut off at a red light, blow warm air, and you'll instantly understand why it's not shutting off when you're asking for AC.

ESS was added as a way to purely cheat the EPA MPG tests. A large portion of the test is spent at idle. By having the vehicle shut off during this time it effectively cheats it. ESS offers nearly non-existent real world MPG benefits but destroys your battery life and added significant complexity to the charging system.

 

[Reinen]

I've seen zero difference in mpg when using ESS vs not using ESS. People with more and longer stoplights than I have may see a little mpg difference.

Here is my suggestion, quoted below from my other post just now on another thread. I'm sorry that I cannot recommend keeping Jeeps Main/Aux battery system in place. You bought a Jeep and its systems should work. But the Main/Aux system doesn't work so well, and is not worth keeping if you have problems. Fortunately, the solution is easy and cheap...
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Some people who drive a lot of short trips will have problems with the Main/Aux system. The Main/Aux system seems to be more than usually sensitive to having enough alternator time to fully recharge. You can have the parasitic situation where the Main and the Aux are both in an under-charged condition, trying to re-charge off each other, and both get damaged.

My guess from reading every damn one of these threads is it has something to do with Jeep's implementation of the dual batteries with inter-dependent charging and interdependent switching for start-up readiness. I'm guessing people who drive short trips would have this issue with the Main/Aux even if they didn't use ESS auto-start/stop. ESS is an extra drain, and taxes the Main/Aux system further, and it's the "cause" of the problem in the sense that ESS is the reason Jeep came up with the Main/Aux system where the Aux is supposed to power accessories (e.g. AC) while the motor is stopped by ESS. (ESS is not the cause in the sense that Jeep could have implemented a better system. For example, Auto-start/stop works fine in Jeep's own eTorque Jeeps.)

This is why bypassing the Aux is the best solution if there is any chance you'll have enough short trips to put your Main/Aux in an undercharged state. Bypassing the Aux costs zero money, is quick and easy, and is easily reversible when you take it to the dealer, if you're nervous about that. You don't have to remove the Aux. It can sit there bypassed. You can still use ESS if you want. The start/stop will work fine with Aux bypassed as long as your Main is in its charged up state, and it helps to not run much accessories during long stop lights with ESS. If the Main is not charged enough for the ESS, worst thing than will happen is you'll get a message that ESS is not available. But with the Aux bypassed, that message is no big deal because you don't have an Aux parasitically trying to devour your Main, nor do you have a system ready to prevent you from starting your Jeep if the batteries are in an undercharged state. Bypassing the Aux just leaves you with the simple one battery situation you're used to. Get a big capacity AGM Main battery and you may have about the same number of amps you'd get with the two smaller batteries in aftermarket dual battery setups.

Turning off ESS is as easy and cheap as hitting the dash button on start-up.
Tazer Mini also turns it off, and there are other aftermarket solutions if you don't want the Tazer Mini.
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Me, I don't mind ESS and my Main/Aux system worked fine with ESS for almost a year while I drove mostly longer trips with plenty of alternator charging time. When I sold a vehicle and used the JLR for my short 4 mile commute to work (last winter), within a month I was having "ESS not available" messages, then other odd dash messages too. Reading up on JLforum here showed me that was the sure sign my Main/Aux system was failing. Sure enough, when I tested them neither battery could hold a charge. Fortunately, I read the jumperless bypass, fuse F42 thread, and haven't had a single problem since I did the bypass. Whether you need to replace your Main or not will depend on how much the Aux system has damaged it, which you can test.
https://www.jlwranglerforums.com/forum/threads/jumperless-aux-battery-bypass.95945/

Actually the best solution is a Cascadia 4x4 hood solar panel.
Always be trickle charging. Keep your batteries at 100% charge and counter the parasitic drain of the JL's always-on electronics.

The problem caused by short trips impacts all AGM batteries. They hate not being at full charge and the parasitic drain of the always-on electronics significantly reduces the battery lifespan. Reducing your battery capacity and redirecting sensitive electronics power to the same battery that is burdened with starting the engine doesn't resolve this. It just makes it worse. The only thing it accomplishes is reducing complexity at the cost of performance and provides a scapegoat to people who can't figure out that Main & Aux are two parts of a single battery system.

 

[STW]

Actually the best solution is a Cascadia 4x4 hood solar panel.
Always be trickle charging. Keep your batteries at 100% charge and counter the parasitic drain of the JL's always-on electronics.

The problem caused by short trips impacts all AGM batteries. They hate not being at full charge and the parasitic drain of the always-on electronics significantly reduces the battery lifespan. Reducing your battery capacity and redirecting sensitive electronics power to the same battery that is burdened with starting the engine doesn't resolve this. It just makes it worse. The only thing it accomplishes is reducing complexity at the cost of performance and provides a scapegoat to people who can't figure out that Main & Aux are two parts of a single battery system.

I agree that constant solar charging is a great idea, but I'm not likely to be doing that with a built-in charger any time soon. I am going to look up the Cascadia since you mention it. Sounds interesting.

I also agree that the Main and Aux are two parts of a single battery system but I haven't liked the results I've had from how that system is designed, how it charges, and how it decides if it will allow a start. When mine failed, I studied the problem to see where my error was, and what options there were for keeping the Main/Aux and getting it to work well enough in my own use, vs not keeping the Main/Aux system. I have yet to see any cost to performance from bypassing the Aux, but it's not impossible. And I agree we need to be aware these modern vehicles have sensitive electronics with more battery drain that vehicles used to have. Jeep's Main/Aux system is here for that reason, generally, but if my reading is correct, the Main/Aux system is mostly there to power accessories while ESS has shut down the motor during longer stops. Minimizing accessories, and/or Minimizing ESS addresses that issue too. We'll see how it goes.

I realize you and I disagree about what the problem is regarding these ESS failures people post about, and which I've had myself. Your argument that the Main/Aux system is misunderstood and misused is probably right, but in my own experience that Main/Aux system is not adequate enough for me to want to keep it in place, even when understood and used correctly.

 

[LouisianaLady]

Ok, i just went back and read you have a manual 2021. Your mpg could be the way you drive it, not saying anything negative there don't get me wrong, but when I had a manual, I probably ran higher rpms than an automatic with a computer controlling shift points would. Rated Mpg I would guess is under ideal conditions with the most conservative shift point rpms. If you are getting 16mpg around town, that's more than likely the standard Mpg for your vehicle. Shut off at stops is when your engine is barely sipping any gas at all. Just see how many hours your jeep will run idling and you'll see what I'm saying.

But I get it, having a warning light on and something not working the way it's supposed to is annoying, especially if you want it to work!

This is my third manual Wrangler Rubicon in a row. Got 17 MPG with my last Rubicon. All three of my Wrangler Rubicons were two doors. 17 MPG+ car had no power package.
As other blogger said, battery sensitive system on newer model Wrangler Rubicons for the many electronics on it.
DO YOU FEEL THAT S/S WORKS BETTER WITH AUTOMATIC WITH POWER STEERING? Or can S/S work equally well/poorly with manual as with automatic?? What fo you think?? Thanks.

 

[Upnarms]

This is my third manual Wrangler Rubicon in a row. Got 17 MPG with my last Rubicon. All three of my Wrangler Rubicons were two doors. 17 MPG+ car had no power package.
As other blogger said, battery sensitive system on newer model Wrangler Rubicons for the many electronics on it.
DO YOU FEEL THAT S/S WORKS BETTER WITH AUTOMATIC WITH POWER STEERING? Or can S/S work equally well/poorly with manual as with automatic?? What fo you think?? Thanks.

No clue, sorry! I was just taking a stab at it. I have the 8spd auto. What is your highway mpg? You can check your air filter, have your spark plugs checked for proper gap, really don't know what else to tell you. You are taking about a 1-1.5mpg difference, not too different than your previous. Your axle ratios may be different from your jk. Are you basing mpg of actual fuel/mileage or off of the computer? You may want to calculate your next several fill ups and see if the numbers are matching the computer estimated mpg.

Good luck, but like most others here I don't think the ess is the problem with mpg if there is one at all.

 

[Reinen]

I have yet to see any cost to performance from bypassing the Aux, but it's not impossible. And I agree we need to be aware these modern vehicles have sensitive electronics with more battery drain that vehicles used to have. Jeep's Main/Aux system is here for that reason, generally, but if my reading is correct, the Main/Aux system is mostly there to power accessories while ESS has shut down the motor during longer stops. Minimizing accessories, and/or Minimizing ESS addresses that issue too. We'll see how it goes.

The Main/Aux system exists to ensure the computer operating the vehicle has clean power without brownouts. The problem with the anecdotal evidence is that a single battery does work, until it doesn't.

During cold starts the Main cranks the starter while the Aux powers the computer which manages the start. The computer will not be effected by the heavy draw of starting a cold engine.

During warm starts (ESS) the Aux powers the starter (which requires less CCAs than a cold start) while the main powers the computer and any accessories which may be running. Again, the computer is not effected by the power draw of the starter. The warm start is also not effected by added electrical accessories that are running, which is a greater issue than a parked Jeep not starting.

With only a single Main there is no isolation between the starter and electronics. The electronics will experience a power brownout to some degree. There will be a point towards the end of the battery's lifecycle where the single main will be unable to operate the starter and electronics simultaneously, but a Main/Aux configuration still would. If a lot of accessories have been added (which is common in Jeeps) that point would come sooner.

Bypassing the Aux is a fix that doesn't actually fix anything.

 

[Upnarms]

The Main/Aux system exists to ensure the computer operating the vehicle has clean power without brownouts. The problem with the anecdotal evidence is that a single battery does work, until it doesn't.

During cold starts the Main cranks the starter while the Aux powers the computer which manages the start. The computer will not be effected by the heavy draw of starting a cold engine.

During warm starts (ESS) the Aux powers the starter (which requires less CCAs than a cold start) while the main powers the computer and any accessories which may be running. Again, the computer is not effected by the power draw of the starter. The warm start is also not effected by added electrical accessories that are running, which is a greater issue than a parked Jeep not starting.

With only a single Main there is no isolation between the starter and electronics. The electronics will experience a power brownout to some degree. There will be a point towards the end of the battery's lifecycle where the single main will be unable to operate the starter and electronics simultaneously, but a Main/Aux configuration still would. If a lot of accessories have been added (which is common in Jeeps) that point would come sooner.

Bypassing the Aux is a fix that doesn't actually fix anything.

Oh it fixes things. Saves you an extra hundred bucks too. Now this is with a caveat that I disable the ESS cause I dont want it. But many folks use the main only with ess without issue from what I see on the forums. Now when the main goes bad, well sure that'll cause an issue too . But it's one bad battery vs 2

 

[Reinen]

Oh it fixes things. Saves you an extra hundred bucks too. Now this is with a caveat that I disable the ESS cause I dont want it. But many folks use the main only with ess without issue from what I see on the forums. Now when the main goes bad, well sure that'll cause an issue too . But it's one bad battery vs 2

So, only one bad battery that will fail sooner and provide no advanced warning of battery failure on a vehicle designed to bring you out to the middle of nowhere.

That's a sucker's fix if there ever was one.

 

[Upnarms]

So, only one bad battery that will fail sooner and provide no advanced warning of battery failure on a vehicle designed to bring you out to the middle of nowhere.

That's a sucker's fix if there ever was one.

Ha, hey that's how car batteries have always worked. All my jeeps in the past had one battery. Never stranded me. Then a 2 battery jeep comes along and all these folks post how they have problems and call tow trucks.

I know you provided good info, not saying it's wrong. But the real world results speak otherwise thus far.

And btw, my two batteries lasted 3 years. My one battery jeeps last...3 years.

 

[Reinen]

Ha, hey that's how car batteries have always worked. All my jeeps in the past had one battery. Never stranded me. Then a 2 battery jeep comes along and all these folks post how they have problems and call tow trucks.

My whole point is that isn't how batteries work now. All your one battery Jeeps were mechanical and the electrical system could actually be shut off by removing your key from the ignition. When parked there was no drain on the battery.

The JL is an electronic vehicle and the electrical system is never off. Systems such as proximity key fobs, touch to unlock door handles, the start button and OTA software updates all consume a small amount of power while the vehicle is off. Customers & government have demanded features which required parasitic drain to be designed into the vehicle. It's a completely different game now.

So don't think a two-battery Jeep showed up and caused problems. The two-battery design is a solution to the always-on electronic Jeep that showed up and the inherent power demand problems that resulted. It spreads the problematic parasitic drain over two batteries, reducing its negative impact to each battery by 50%. It isolates the power sensitive electronics from sudden high demand events like engine starts. ESS kicking in indicates a successful battery check. When ESS fails to work due to Battery Charging, that's a clear 2-3 month warning before the Jeep will be unable to start.

As I said, reverting your electronic Jeep's battery system to a configuration designed for a simpler mechanical vehicle does nothing to address the root problem.

People have their Jeeps towed for battery issues because:

• They don't understand, ignore, and sometimes even disable the JL's clear warning signs of impending battery failure.
• They do not realize that replacing the Main or Aux without replacing the other is the worst possible thing you can do if you want to be free of battery issues.
• They do little to nothing to offset the built-in parasitic drain when the Jeep is parked for long periods or the incomplete charge that results from short drives. They just let it destroy the batteries.
• They assume they already know how to jump start the JL using the same technique as a single battery vehicle, which often doesn't work. The procedure for jump starting a dual battery JL is different. Starting a JL being jump started may also require a different procedure.

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