Auto Start/Stop Not Working....Fix it?

[bdaviskc]

I have a '23 Wrangler Sahara JLU--auto start/stop function stopped working about 18 months ago. It is as if it doesn't event exist--car functions fine without it, no warning/error lights or issues and I never have to turn it off. Factory warranty ends at the end of October (28k miles at the moment)--should I have this repaired under warranty or just go on my blissful way without it and not worry? Not sure what to do here.....thanks for any opinions!

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[rickinAZ]

ChatGPT to the rescue. Personally, AI's answer has me leaning to have it fixed. But, then again, I have mine defeated (but still operational).


That’s an interesting situation! It sounds like the auto start/stop feature just stopped working one day, and you're not seeing any error codes or issues beyond that. I think there are a couple of things to consider here:

1. Factory Warranty Consideration: Since the warranty is about to expire soon, you could take it in and have it checked out to see if there's a simple fix or a deeper issue that needs attention. This would be your last chance to get it covered under warranty, and it might be worth it to have a dealership diagnose it, even if it's just for peace of mind.
2. The Comfort Factor: Some people actually prefer not having the auto start/stop function, as it can be annoying at times, especially in stop-and-go traffic. If you’re happy without it and it hasn’t caused any other issues, it might not be worth the hassle to repair. It’s one of those features that some folks use regularly, and others barely notice when it’s gone.
3. Long-Term Effects: Even if you’re happy without it, there could be an underlying issue that could lead to other electrical or powertrain issues down the road. Having it diagnosed might help avoid any potential future problems.
4. Future Resale Value: If you plan to sell the vehicle soon, some buyers might expect that feature to be fully functional. But, if you’re not planning on selling anytime soon, this likely won’t be a big concern.

Ultimately, if you’re not bothered by it and you’ve been driving just fine without it, you might be okay leaving it as-is. But getting a quick diagnosis at the dealership before the warranty expires could give you clarity and help prevent any unknown future issues.

 

[Werg1081]

I would recommend having your batteries tested. I think I remember hearing that when the Aux battery starts to go the ESS function may stop working. Also, if you do replace batteries make sure to do both at the same time.

 

[AndySpill]

should I have this repaired under warranty

Yes, and not because you seem to have any great desire to run ESS events but rather because you want to know that you have a strong main battery and nothing that risks compromising it like a defective Aux battery, as is consistent with the ESS system not engaging.

Have the dealer load (not multimeter) test each battery independently. As Ryan said @Werg1081, if one battery is shot replace both.

After this, if you want to, with fresh batteries, bypass the Aux battery using one of the techniques of this forum, and turn ESS off, then feel free to do so.

If you have your own load tester you can test the batteries by first removing the black factory cable off the main battery's negative terminal that doesn't have as its distal end the body ground on the passenger side panel under the hood.

Keep this cable you took off the main battery's negative terminal away from metal. It's distal end, sight unseen is the negative post of the Aux battery.

Now put the load tester on the main battery's posts. This is a test of only the main battery.

Move the negative portion of the tester off the main battery's negative post and place it on the the loose cable's end. This is a test of only the Aux battery even as the load tester's positive lead remains on the main battery's positive post.

Put the cable back on when done.

Load or multimeter testing of the main battery's posts while that battery is connected to the Aux battery can yield misleading results given the 2 batteries' parallel connection with one another, one battery potentially masking the weaker one. Multimeter testing can also be misleading as only load testing reveals a battery's ability to deliver power: the true test of a battery.

 

[Cartman]

Same for me, but it starts working after I had replaced AUX battery.

 

[bdaviskc]

Thanks for all the feedback--seems the wise thing to do is have it checked out. Will go with that! Had not thought to ask ChatGPT--interesting suggestion! Again, thanks to all who responded.

 

[GabeBoyTheGreat]

Did you check the ESS menu in the instrument cluster? Normally, this menu will tell you why the ESS is not functioning, though I suspect the others are correct that one of your batteries is going bad.

 

[Cartman]

My instrumet cluster screen allways said only that start stop is not ready. No reazon why. Now it sayz ready/on/off.

 

[AlgUSF]

Same for me, but it starts working after I had replaced AUX battery.

Same here. Quietly stopped working, replaced main and aux and it started working again. My batteries were 4 years old from vehicle purchase date.

I always disable ESS with the button when I leave my neighborhood.

 

[GabeBoyTheGreat]

My instrumet cluster screen allways said only that start stop is not ready. No reazon why. Now it sayz ready/on/off.

Yea most likely a battery issue. Based on the message you saw, I think that is the ESS battery that needs to be replaced.

However, some people recommend replacing both batteries. You could also consider doing the AUX battery delete. Saves you money in the long run.

 

[Cartman]

I'm just unhappy if something doesn't work on my car. What's more, for me it got worse, because the aux drained my main battery. When I replaced the main battery, it drained it to 4.5V again. Then I disconnected the aux and everything worked, even the start/stop worked with only the main battery, but I simply think the aux has its own meaning in the syatem. The only thing I'll replace it with in the future will be a full-fledged large battery.

 

[Sanchese]

I have a 2022 with e-torque doing the same thing.
I do not have an aux battery.

 

[Squibbles]

I would recommend having your batteries tested. I think I remember hearing that when the Aux battery starts to go the ESS function may stop working. Also, if you do replace batteries make sure to do both at the same time.

Is it necessary to replace the main battery when replacing the auxiliary battery. I’ve often heard replace the auxiliary battery at 3 years with an upgraded one but I have the tow package with the upgraded battery and alternator. I figure replace the main battery with an optima a littler later since no issues with either one.

 

[AndySpill]

Is it necessary to replace the main battery when replacing the auxiliary battery. I’ve often heard replace the auxiliary battery at 3 years with an upgraded one but I have the tow package with the upgraded battery and alternator. I figure replace the main battery with an optima a littler later since no issues with either one.

I will answer yes.

I will do so because given the parallel connections of the batteries, either battery, at the end of its useful life risks becoming cannibalistic to the other, and it is cheaper IMHO, if you've committed to run both batteries, to replace them both than first replacing the Auxiliary battery, having a dying main battery destroy it, and then replacing both batteries.

It's just that we hear of this cannibalistic effect more as the Auxiliary battery dying and taking the main out with it; but it can work both ways.

I am also of the opinion that there is little reason to run both batteries, and that you should bypass the Auxiliary battery (links available upon request) if you are content with not running engine start stop events (ESS).

(In a better version of the dual battery ESS system Stellantis devised here I would have wanted to see identical sized (and chemistry) batteries switched by the vehicle periodically regarding which played the role of running ESS events.)

I have no horse in this race; no desire for you to configure your Wrangler like mine in some confirmation bias way I've seen some forum members push their mods. I run both batteries and ESS events, but I also have a roof rack with allows me trickle charge both batteries via solar panels with no additional effort beyond initial installation. But that's just me.

 

[Danjeepman57]

What year did they start putting aux batteries in Jeeps? I have a 2018 JL and want to know if I will be seeing this.

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