Service Stop/Start System Message and Warning

[Thor64]

Hi Guys,
This morning my 2019 dash displayed service Stop/Start System warning message and then latched the warning circle on the display. Thought it might be an auxiliary battery issue but did the bypass by pulling F42 and disconnecting the aux battery neg cable. No luck—still have the same issue—any ideas??? I do have a Tazer mini installed to disable it and have had it installed for 3 years with no issues. Thanks!!!

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[58Willys]

Load test both batteries separately, go from there.

 

[Opus]

It's possibly the damage has already been done and the auxiliary battery has drained your main battery enough that it need to be replaced. If it's the original 2019 battery, you're likely due for a new one regardless.

 

[Reinen]

If your Aux battery is failing your Main is at best almost failing. The Aux battery delete is not a panacea. It hides just as many issues as it resolves.

If you still have the original batteries they have lived a long life and are overdue for replacement.

 

[Thor64]

Main battery replace about a year ago with Optima yellow top and auxiliary batt replaced 2 years ago under warranty.

 

[zouch]

load test them both.

2 years is not an unheard of time for the stock Aux Batts to fail.
sadly, it may have taken down your Optima as it was failing. (Optimas are not what they once were.)

Main battery replace about a year ago with Optima yellow top and auxiliary batt replaced 2 years ago under warranty.

 

[AndySpill]

@Thor64 Dan:

While I firmly believe that the advice prior posters on this thread gave you to independently load test the batteries is wise, let me add some color commentary here.

It's been my experience that the ESS off light in the dash will clear itself after the next cold crank in which an adequately charged, or what your factory dual AGM battery JL thinks is the Aux battery is adequately charged.

Let me break that down.

Just prior to cold crank the factory dual AGM battery JL will attempt to energize the Power Control Relay (PCR) to separate the batteries and test the Aux battery. Since you pulled Fuse 42 the PCR cannot energize to separate the batteries and this test instead goes to all batteries, of which you only have connected your main battery.

So the fact that this ESS off light isn't getting cleared may indicate a main battery that is in need of replacement.

The gold standard test on this is load testing: which measures a battery's ability to accept and deliver charge: that which a battery needs to do.

 

[VKSheridan]

If your Aux battery is failing your Main is at best almost failing. The Aux battery delete is not a panacea. It hides just as many issues as it resolves.

I’m curious to your last comment.

Within the first few months of new ownership, my 2020 JL refused to be reliable. In fact, the “ESS Not Ready” was lit when I drove it off the lot. The dealer said it was because it was sitting for so long and I was too enamored with my purchase to not question that. If my Jeep sat more than a few days off the battery maintainer, it would need a jump. The dealer threw two sets of batteries at my Jeep and when it stranded me again, I deleted (not just disconnected) the auxiliary battery. That’s been over 2 trouble free years ago.

While I agree the factory parasitic loads that discharged the auxiliary battery remain, parasitic load has yet to prove itself an issue. What hidden issues are you referring?

 

[AndySpill]

If your Aux battery is failing your Main is at best almost failing. The Aux battery delete is not a panacea. It hides just as many issues as it resolves.

If you still have the original batteries they have lived a long life and are overdue for replacement.

I agree that the Aux battery delete is not a panacea. For starters, if you take this battery out of the electrical schematic of the vehicle I would recommend not running ESS events, as your ESS battery and post ESS event cranking battery are now one and the same (which by the way is how most auto makers have it, but Stellantis may have designed aspects of their ESS for two batteries.)

But the people who miss ESS are far and few between and I'm just not aware of the issues that deleting this battery raises, let alone that counterbalance the advantages of not having it if you've committed to not running ESS events.

Of course there's the issues of climate change and to whatever small but measuring extent ESS systems save on combusting fossil fuels...especially small when counterbalanced against the green footprint of the ESS systems themselves.

I have no horse in this race. I run both batteries and ESS events, but the latter is only possible for me via battery charging from a solar power I have on an already needed for other reasons roof rack.

 

[dchemphill1]

My $.02, delete the aux battery removed fuse 42 and push a button the rest of the jeeps life.

 

[Reinen]

I agree that the Aux battery delete is not a panacea. For starters, if you take this battery out of the electrical schematic of the vehicle I would recommend not running ESS events, as your ESS battery and post ESS event cranking battery are now one and the same (which by the way is how most auto makers have it, but Stellantis may have designed aspects of their ESS for two batteries.)

The JL was designed with two batteries because Jeep owners expect to be able to install aftermarket electrical accessories directly to the Main battery. It's a very common practice. Instead of putting limits on that practice, Stellantis engineers opted to protect the power-sensitive JL electronics from this unknown owner-installed power demand by powering the electronics with an 2nd Aux battery that is isolated from these modifications during ESS events.

Other auto makers have the luxury of assuming the owner will not alter the OEM electrical system as it's a fairly uncommon thing to do. They will also be very quick to blame any failure on the owner-installed modification. Jeep customers do not allow such a luxury.

It's ironic. Jeep's customers love to complain about the Aux battery when the only reason why it exists is because of Jeep's customers. Engineers can't win for losing.

But the people who miss ESS are far and few between and I'm just not aware of the issues that deleting this battery raises, let alone that counterbalance the advantages of not having it if you've committed to not running ESS events.

#1 reason is that it also deletes a degree of reliability and ability to perform preventative maintenance before failure. A Jeep is a vehicle where you cannot assume Roadside Assistance is available or even cell service.

With Aux Batt/ESS as designed, every time ESS engages confirms a successful battery check. It would take beyond OCD-level maintenance to check the batteries more often. In the event of battery failure the first thing to fail is ESS. As you well know, nobody cares if ESS fails. But it does give you a 2-3 month warning that a critical battery failure will occur that will leave you stranded. More than enough time to perform preventative maintenance. It's a very valuable "canary in the coal mine".

With Aux Delete/ESS Disabled, your first sign of battery failure (which is inevitable) will very likely be a critical failure that leaves you stranded, unable to start the vehicle. For someone like me, who owns a JL specifically to go deep into areas with no infrastructure, no roadside assistance and no cell service this is utterly unacceptable. It will very likely lead to an extremely inconvenient and potentially life threatening situation. Even if you always stay in civilization, why would you delete a very convenient passive warning that allows you to replace your failing batteries at your convenience? Ain't nobody got time for dead transportation. I don't understand the mentality behind it.

Of course there's the issues of climate change and to whatever small but measuring extent ESS systems save on combusting fossil fuels...especially small when counterbalanced against the green footprint of the ESS systems themselves.

Welcome to the genius behind Washington DC. It doesn't make much sense but vehicle manufacturers have no choice, it's a must-have "feature" now. At least Jeep had the wherewithal to turn it into a 2-3 month battery failure warning. Now that is a valuable feature that few other vehicles have.

 

[VKSheridan]

Even if you always stay in civilization, why would you delete a very convenient passive warning that allows you to replace your failing batteries at your convenience? Ain't nobody got time for dead transportation. I don't understand the mentality behind it.

Like others, I go deep into the backcountry with some places having no roads. Crawling an alluvial fan, no cell coverage and long walk out if my vehicle won’t crank.

My JL stranded me 4 times prior to deleting the hardware. No warning, no canaries in the coal mine, just a Christmas tree dash to let me know my day was taking a turn. If you think it gives you warnings, the reality I’ve faced suggests you’ve been misled.

Luckily, none of the strands happened while soloing but things could have been worse. Jumper cables got me back on the road but required an additional vehicle present to jump from.

After two full battery replacements within months of new ownership by the dealer, I actually carried spare batteries so it wouldn’t require a jump from my single battery PowerWagon that doesn’t have ESS and can be upgraded beyond a light bar on a Jeep with a friggin’ camper.

My Jeep has performed flawlessly the past two years since deletion. I’m not theorizing success or risk nor sharing a mere opinion, I‘ve lived through it.

I still carry a spare battery because batteries fail but thus far, it’s just been cargo, along for the ride when I’m out in the Mojave.

I prefer the root cause be identified and addressed versus deletion but getting to the bottom of this has been all but elusive. After all this time and the number of vehicles involved, Jeep has not been forthcoming with any guidance.

 

[Reinen]

Like others, I go deep into the backcountry with some places having no roads. Crawling an alluvial fan, no cell coverage and long walk out if my vehicle won’t crank.

My JL stranded me 4 times prior to deleting the hardware. No warning, no canaries in the coal mine, just a Christmas tree dash to let me know my day was taking a turn. If you think it gives you warnings, the reality I’ve faced suggests you’ve been misled.

Luckily, none of the strands happened while soloing but things could have been worse. Jumper cables got me back on the road but required an additional vehicle present to jump from.

After two full battery replacements within months of new ownership by the dealer, I actually carried spare batteries so it wouldn’t require a jump from my single battery PowerWagon that doesn’t have ESS and can be upgraded beyond a light bar on a Jeep with a friggin’ camper.

My Jeep has performed flawlessly the past two years since deletion. I’m not theorizing success or risk nor sharing a mere opinion, I‘ve lived through it.

I still carry a spare battery because batteries fail but thus far, it’s just been cargo, along for the ride when I’m out in the Mojave.

I prefer the root cause be identified and addressed versus deletion but getting to the bottom of this has been all but elusive. After all this time and the number of vehicles involved, Jeep has not been forthcoming with any guidance.

Well, I managed to go 3.5 years on OEM batteries and I only changed them because they were OEM batteries and due to fail, not because they did fail or showed any signs of it. 3.5 years on OEM was a good enough run and I didn't want to push my luck.

First of all, Mopar OEM batteries are bottom of the barrel. Nearly any aftermarket battery is better. Second is that Jeeps can sit on the dealer lot for months and the sub-par OEM batteries do not handle this well at all. A battery in a new Jeep off the lot can already be significantly worn.

I attribute the longevity of my OEM batteries to two things.

1. I custom ordered my JL with the tow package and larger battery. It sat on the dealer lot less than 24 hours leaving little time for the JL's parasitic drain to do its damage.
2. I have a hood solar panel that constantly trickle charges the batteries during the day. This isn't to charge a dead battery, that will take days. It's to counteract the JL's parasitic drain and always keep the batteries topped off. This significantly reduces the progressive damage caused by the JL sitting idle.

I'm pretty sure you got a new JL with an already damaged battery. The dealer just replaced your damaged crap battery with another crap battery. And dealers often only replace one of the two batteries, which will severely reduce the battery lifespan.

It doesn't make any sense that your problems would go away by reducing battery capacity. There is some other important detail missing.

 

[alphawolff]

How do we go this many replies without anyone just telling the guy to pull the damn codes with his tazer? A service S/S light can be caused by any 100 different things, none of which are related to the batteries. Could be a damn failing hood switch, they go bad all the time. A pending DTC will cause this message without a CEL being thrown.

The JL was designed with two batteries because Jeep owners expect to be able to install aftermarket electrical accessories directly to the Main battery. It's a very common practice. Instead of putting limits on that practice, Stellantis engineers opted to protect the power-sensitive JL electronics from this unknown owner-installed power demand by powering the electronics with an 2nd Aux battery that is isolated from these modifications during ESS events.

This is incorrect. The two battery system was designed to reduce voltage spike conditions during a stop start event. During early design iterations it was found during an engine start the voltage spike was enough to cause a hard reset of the radio. To prevent this, they isolated the interior electrical system to a secondary battery during a stop start event. The aux battery is purely for NVH. All of our vehicles use this two battery setup except for the early Cherokees, which used a set of capacitors and relays instead to a much less reliable effect. Every notice how your radio blacks out when you crank the engine? Imagine that happening during every time stop start activates, interrupting whatever you're listening to.

This was taught to us during training. I have no idea where you got this idea from.

 

[VKSheridan]

First of all, Mopar OEM batteries are bottom of the barrel. Nearly any aftermarket battery is better. Second is that Jeeps can sit on the dealer lot for months and the sub-par OEM batteries do not handle this well at all. A battery in a new Jeep off the lot can already be significantly worn.

I'm pretty sure you got a new JL with an already damaged battery. The dealer just replaced your damaged crap battery with another crap battery. And dealers often only replace one of the two batteries, which will severely reduce the battery lifespan.

It doesn't make any sense that your problems would go away by reducing battery capacity. There is some other important detail missing.

I’m glad you’ve had a great ownership experience that I’ve been denied and you’re a member of the “unaffected” club. I had to take steps just to be an honorary member……

The first three batteries were indeed Mopar. The set that came with the Jeep and the two sets the dealer replaced. Unfortunately for your hypothesis, the dealer installed the same Mopar brand that‘s in my PowerWagon and Challengers. None of those vehicles have ESS or the lil’ Mopar auxiliary battery.

My Jeep has neither as well now.

The last set were Interstate batteries that I bought and installed myself in an airport parking lot. They too were not immune to the gremlins with just 4 days of sitting.

I cannot explain why some Jeeps can exist with two battery configuration and mine is one of the thousands that cannot.

Yes, there is something different between my Jeep and the others.

A different supplier for one of my ECMs that forgot to put logic in to stop parasitic voltage draw if too low?
An alternator whose field windings intermittently energize with key off?
A loose ground or stray voltage source that frequently restarts ECMs, the dash and radio heads?

No clue and I’ve lost the willpower to look for it.

The common reply from Jeep and the inexperienced is to blame the owner for adding a winch or lightbar, leaving the dome light on or always arming their security system. Yet all these brainiacs stumble when I ask them how deleting the auxiliary battery fixes the owner’s ignorances instead of make those deficiencies even more pronounced.

I hope you never have to delete your battery and can enjoy hundreds of thousands of miles from your ride with it performing as intended. For those who are less fortunate, I recommend full deletion, disable ESS and move on or trade it off before it destroys your faith in Jeep.

Peace

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