Auto Stop/Start Stopped working.

[ShadowsPapa]

yeah, seems like I got lucky I had someone who knew what they were doing. They had to trace all of the wires and connections. I’m not entirely sure which one it was but they said there is a core grouping of wires that run the length of the truck like a spinal cord and it was one of the wires in that bundle near the rear they had to repair. Start/stop was the only thing not working at the time (that I knew of). The strange thing is when they first replaced all of the batteries and IBS the Avenger light finally came on; prior to I had no lights.

Interesting that they replaced the IBS....... because FCA says not to unless some very specific codes are found. They say "reset, don't replace unless.........." but hey, it's their dime! I'd not tell them not to. And for all we know, there may be a revision to it as well.
Very interesting on the wires - man, I'd love to have seen exactly where they went with that.
Oh, well - the point is - they fixed you up and all is fine again.
Likely you had multiple things going on and often one thing can mask another - C won't show up until or unless A and B are fixed.

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[bjohnsonmn]

My impression and opinion is because of the experience I've had from the beginning. At 3500mi, the battery had a bad cell. The tech at the dealer told me they have had a lot of those on the aux batteries.

Then at about 4300 miles, TIPM failed in a way related to the S/S system. Now I'm at the third issue related to it.

Perhaps it sounds like hyperbole to place an unethical label on it. I work with engineers in an industry that those sorts of "we will figure it out as they pop up" items would cause dismissal. That said, take the first year or two to work the bugs out, but at least put out a TSB or similar that makes it clear that they aren't simply hoping it goes away by throwing more and more parts at it.

 

[Dougstdig]

Do you mean rear of the cab, inside right rear area?
Or the rear rear of the truck?
Asking to sort of try to think through "what might be there" that is in play with ESS.
In the rear of the cab is the BCM.
Behind the cab is the fuel system wiring and other nifty stuff.

These have a long list of over 20 items that must fall into line before ESS will operate and that does not include engine related things the PCM tracks - so likely we're talking over 100 things and you won't get a message on any of those except a handful - HVAC- cabin cooling/heating, steering column angle, outside temperature too hot or too cold you'll get messages but most of the rest, no message.

Sounds like you got a guy who cared and knows his stuff.

It's not always about batteries.

]

Yep. Sometimes you get a light and don’t know that the cause of that seemingly unrelated light prevents the ESS from engaging. The one I’m referring to is the seatbelt light. If you don’t have your seatbelt engage, the electronic stop start will not function and this is confirmed in the owners manual.

 

[JTSouthernYankee]

I've noticed right when my Avengers light is about to turn on is when either sitting at a red light or just some random starting after doing some running around but the engine stutters really bad usually after starting it or if I'm sitting at a red light it will stutter just a little and then like always that stupid light comes on. I do have the Pulsar programmer and it has the ability to remember that I have turned off the Auto Stop/Start. Ive been guessing that I've had it off for so long that it never let the secondary batt charge? lately though the programmer hasn't been remembering to keep the system off but the truck never stops at any red light or sitting in traffic. none of this bothers me from to the light to it never working. I wish I could just rip the stupid system out and be done with it.

 

[ShadowsPapa]

Ive been guessing that I've had it off for so long that it never let the secondary batt charge?

Aux battery charges no matter what.
It doesn't matter if you have ESS enabled or disabled. That battery is connected to the charging system - the truck's electric systems, at all times and receives the same voltage that the main battery receives when the truck is running.
The batteries are also connected in parallel when the truck is sitting in your garage so if one is less charged than the other, the battery with the higher charge will "push" to the other battery until they are equalized.
Example - if the main battery is sitting at 12.6 and the aux battery is sitting at 12.4, they will eventually equalize until the voltage at each is the same somewhere between 12.6 and 12.4
If the aux battery is sitting at a higher charge, higher voltage, it will push to the main battery until they are equal. That's batteries in parallel.

I wish I could just rip the stupid system out and be done with it.

You can do a simple 'delete' that's talked about in a thread here by disconnecting the aux battery negative at the crank battery negative (that's where they tie together) and pull the fuse for the PCR relay. (I believe it's fuse F42)

Note that if your main battery is weak, it will show up more doing that and if the aux battery was a problem, you've just taken it out of the equation.
Several here have found the main or crank battery to be the issue, others have found the aux battery to be a problem. And some find they both fail at about the same rate.

 

[Jeep-A-Kneez]

Back in the barrel again with this issue, had the main battery replaced a few months ago, start/stop worked for a while and then out again. Auxiliary battery replaced a week ago, worked 3 times, out again. I've opened a case with @JeepCares in the hopes of, or at least getting closer to finding a resolution to this issue. Truck has already been in the service department about 8+ times in for this problem with only short term success.

Truck is a daily driver, at least 80 miles 5 days a week and most of that is highway speeds, 55 to 75 mph. I would like to think that would rule out the "not driven enough" thoughts. I do monitor voltage here and there, yesterday was the highest I've ever seen at 14.8v, even at idle. When I cut the truck off voltage was 12.6 and 12 hours later it's at 12.1v. Battery issues still yet??

With only about 2400 miles remaining on the factory warranty, and a heavy service department rap sheet that goes well beyond the start/stop, guess I need to research an extended warranty option, lemon law, another vehicle, something.

 

[ShadowsPapa]

I do monitor voltage here and there, yesterday was the highest I've ever seen at 14.8v, even at idle. When I cut the truck off voltage was 12.6 and 12 hours later it's at 12.1v. Battery issues still yet??

14.8 is pretty normal in colder weather and/or when the batteries are low.
12.6 is not a fully charged battery. 12.7-12.8 is
12 hours later being down to 12.1 is bad news.
Either a battery has no capacity or there's a huge drain. Most likely capacity issue with battery.

If you have the stuff - an AGM capable battery charger (not a trickle of 4 amps or less but a real charger of 10 amps or more) you can pull the negative battery cables off the top of the IBS which sits on the negative terminal of the main/crank battery.
Separate the two black cables. One goes to the aux battery and serves as ground for that battery, the other goes to the fender and grounds the batteries to the chassis.
Use a volt meter and check the voltage of the aux battery and see where it stands. Meter to the main battery positive and to the black cable that goes down to the aux battery.
Charge the aux battery - use the one that goes to the aux battery - connect charger to that cable (likely was the lower of the two black cables, the one that goes on the IBS first) and to the main battery positive. That will charge the aux battery.
After the aux battery is charged - check the voltage of that battery again.
If you can let it sit a few hours, check the voltage of the aux battery again later because it won't have a load on it - it's disconnected with that ground cable off and it should stay up.

After the aux battery is fully charged -

Remove the IBS from the truck and set it aside - this will reset it after a few minutes.
Check the voltage of the main battery.
Charge the main battery - charger on negative terminal and on positive terminal.
Once that battery is fully charged, check the voltage.

If you can let it sit a few hours, check the voltage of the main battery after several hours - it should stay around 12.7 or better because there's no load on it, it's disconnected.

Put the IBS back on the main battery, put the two ground cables back on the IBS.
You will likely get a spark and that's normal because there's always some load with these trucks just itching to draw from a battery.


You have just reset the IBS and put it on two fully charged batteries so it's all starting from scratch.
ESS may not function for a start cycle or two, and after a few hours. But the IBS usually learns and things start working again fairly quickly, within a day normally.

 

[Jeep-A-Kneez]

14.8 is pretty normal in colder weather and/or when the batteries are low.
12.6 is not a fully charged battery. 12.7-12.8 is
12 hours later being down to 12.1 is bad news.
Either a battery has no capacity or there's a huge drain. Most likely capacity issue with battery.

If you have the stuff - an AGM capable battery charger (not a trickle of 4 amps or less but a real charger of 10 amps or more) you can pull the negative battery cables off the top of the IBS which sits on the negative terminal of the main/crank battery.
Separate the two black cables. One goes to the aux battery and serves as ground for that battery, the other goes to the fender and grounds the batteries to the chassis.
Use a volt meter and check the voltage of the aux battery and see where it stands. Meter to the main battery positive and to the black cable that goes down to the aux battery.
Charge the aux battery - use the one that goes to the aux battery - connect charger to that cable (likely was the lower of the two black cables, the one that goes on the IBS first) and to the main battery positive. That will charge the aux battery.
After the aux battery is charged - check the voltage of that battery again.
If you can let it sit a few hours, check the voltage of the aux battery again later because it won't have a load on it - it's disconnected with that ground cable off and it should stay up.

After the aux battery is fully charged -

Remove the IBS from the truck and set it aside - this will reset it after a few minutes.
Check the voltage of the main battery.
Charge the main battery - charger on negative terminal and on positive terminal.
Once that battery is fully charged, check the voltage.

If you can let it sit a few hours, check the voltage of the main battery after several hours - it should stay around 12.7 or better because there's no load on it, it's disconnected.

Put the IBS back on the main battery, put the two ground cables back on the IBS.
You will likely get a spark and that's normal because there's always some load with these trucks just itching to draw from a battery.


You have just reset the IBS and put it on two fully charged batteries so it's all starting from scratch.
ESS may not function for a start cycle or two, and after a few hours. But the IBS usually learns and things start working again fairly quickly, within a day normally.

Great advice, appreciate that. Will try to get some cold voltage readings and pictures for the service department.

 

[Jeep-A-Kneez]

Here are the readings I got, truck has been setting for a day, will have to compare these readings to those after running for an hour or so. A correction to my earlier post of 12.1v was with the door open, voltage was a whopping 12.2 with the door closed.

 

[ShadowsPapa]

What's happening in that last picture is that the aux battery is still fully in the system and powering the load of the electronics as long as the two black original factory cables are connected together.
The aux battery ground comes up and goes onto the IBS that is clamped on the main battery negative terminal. Then the body/chassis ground cable from the fender connects to that. So the aux battery is grounded because it's still connected to the final ground cable.

On a 2020 like I had, in this picture, the cable numbered 1 was the aux negative cable and the cable numbered 2 was the ground from both batteries to the fender.

2021 changed that. Now cable I have marked with 1 is the chassis ground cable and 2 is the aux battery ground/negative cable.
To unground the aux battery and take the load off of it, you have to take off the nut that holds these two cables together.

This is how you charged the aux battery and measured aux battery voltage in a 2020 -
but for 2021 and later, you need to take the other cable off the IBS and use it to measure the aux battery and charge it.

 

[Jeep-A-Kneez]

Back out for an update on isolation of auxiliary battery voltage.

 

[ShadowsPapa]

Man, you are a quick study!
Low - meaning not fully charged, but not horrible, either.

If it was mine, I'd go for a charge of each individually, leaving the IBS off the battery/disconnected while doing so, to reset it, and going from there.
But it sounds like a dealer trip may be in the near future.

 

[Jeep-A-Kneez]

Man, you are a quick study!
Low - meaning not fully charged, but not horrible, either.

If it was mine, I'd go for a charge of each individually, leaving the IBS off the battery/disconnected while doing so, to reset it, and going from there.
But it sounds like a dealer trip may be in the near future.

Yeah man, thanks. I too believe 12.4v is a touch low but not excessive. Even though it is a headache on both sides, this is an issue that needs to be solved, though sometimes I think it is costing me more than Jeep.

Now, old school logic says that an increase in voltage = decrease in amperage and I would like to think that 14.8 volts is towards the upper end of charging and at this point amperage should be next to nothing, trickle at most.

At this point, since no bells and whistles are going off, things could be pointing to the batteries again. Or maybe the alternator is having issues with amperage output. Regardless, the system is being very picky and needs to lower it's standards.

 

[wakeup2river]

I’ll just add my problem/solution for the database here.

I noticed mine hadn’t been working for about a month. The dash just said “not ready”. It said nothing about charging no other comments except the usual if your tires are turned it won’t be ready or the truck is warming up. I did notice that my battery voltage never left 14.2-14.4 volts. Never thought much of it until my buddy bought the same truck and his jumped around as low as 12.5 then 13 sometimes 14 volts.

I took mine in and the dealer immediately said both batteries are shot based on their test. I got both replaced under warranty ( would have been $813) and it’s been perfect ever since.

 

[Wasatch1]

This story has gone on too long! LE Rubicon, worked 1 year great. Then drama. Dealer batteries replaced 1st time, 2nd stop just charged, say I'm not driving it enough!? High load camping with gear up canyon 80mph 9k elevation, then works for 1 week, then dead for months. I dont want to add a battery tender and plug/unplug daily for my own repair. This is a mess. Recall, recall, recall! 'Jeep we care' fix my dang truck!!!

Well, I'm back... the above was my post in Oct. So, I bit the bullet and got a $2500 ex Jeep warranty. Since ESS hasn't worked for months, load or not, I took it in today. This time replaced aux battery, with a $593 bill, saying new warranty doesn't cover batteries? So, I complained about this was my 4th time in for the same issue and in 3 years the system has only worked for 1. Their records showed last batteries they changed were less than 2 years old, so, thankfully erased the bill under Jeep factory warranty. I paid this Jeep dealership for my new warranty, so I don't know the difference, i will look into that... One day in it works! I'm going resort riding/skiing big load once a week, daily driver but fairly mild miles to work, etc... Spirited driver, so revs are pretty solid. I guess, I will keep posting until this disaster flaw is solved by Jeep, not me!

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