Has it Happened

[Wbino]

[QUOTE="AndySpill, post: 3194845, member: 99074
Wow, for a bunch of reasons this wasn't the response I expected. Soap box ascending time.

I've been on this forum for a long time and I wouldn't expect that response either. There are a lot of very long threads on this forum about the dual battery system and related modifications, with a lot of input by people who know a lot about the Jeep system. So modifying the system is not just fooling around under the hood. However it is a modification of the Jeep and I would always attempt to put the Jeep back to factory condition before taking it to the dealer. YMMV, some dealers will use anything as an excuse to deny service, some won't.

I've been involved in auto repair for a long time, my father owned a repair business for over 60 years. I am unlikely to ever take my Jeep to a dealer for anything. My recommendation unless the OP's vehicle is almost brand new is for them to buy a battery brand that they trust and throw out the OE battery. There are too many reports of the OE battery not being very good and not lasting very long. I bought my Jeep used and at 3 years old I put a new battery in it, and discovered that my 3 year old Jeep had a 2 year old battery in it meaning the original battery was replaced at 1 year age.
[/QUOTE]
Just to counter I have a 2021 delivered from the factory in March 2021 and still have the same 12v battery. I'm going to replace it before the winter comes just because, but I will probably get the same one from the dealer as I've had good luck with this one.

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[roaniecowpony]

Glad I don't have to wring my hands about warranty.

 

[Terrymo]

Glad I don't have to wring my hands about warranty.

Yeah but for me right about now with a blown radiator and possible combustion leak, my sweatshirt doesn’t seem so funny anymore

 

[Terrymo]

Wait! Nobody told me we got paid per word here or that throwing in stuff we found in a thesaurus paid more.

 

[AndySpill]

Sorry, I couldn't make it though that. ChatGPT turned those 1,314 words into:

That's actually fair retort John. Here's mine.

ChatGPT failed to tell you why "bypassing Jeep JL’s aux battery is a harmless ESS fix; warranty denial unlikely." It lacked commentary on why people do it, why it's more than harmless but beneficial, and because it is so, in addition to Magnuson-Moss, why service is unlikely to be denied, as I explained.

John I would have been thrilled if this thread had monosyllabic responses to my initial question, in turn leaving me with simply answers to a simple question that involved no retort.

Instead people who don't know what they are talking about offered ridiculous off topic responses, and I schooled them. If they weren't so wrong, I'd have nothing to correct.

But were not giving ChatGPT a chance to make good. Let's do that.

ChatGPT: why is Bypassing Jeep JL’s aux battery is a harmless ESS fix for which warranty denial is unlikely? All of sudden not even AI can get that done to one sentence. Heck, it's probably lengthier than my response. It's very good, but, sigh, it requires words, just like I did.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


Why It's Considered Harmless

1. ESS Malfunctions Are Battery-Related:
   • The Jeep JL uses two batteries: a main battery and a small auxiliary battery.
   • The aux battery is primarily responsible for powering accessories and enabling ESS to restart the engine after it shuts off.
   • When the aux battery fails, it can cause ESS to malfunction, trigger warning lights, or even cause starting issues.
   • Bypassing it resolves these issues without introducing new ones, as long as the main battery is strong and healthy.
2. Bypass Doesn’t Disable Core Vehicle Functions:
   • Bypassing the aux battery simply reroutes power so that the ESS system and accessories draw from the main battery instead.
   • It does not affect the engine, transmission, brakes, or other safety-critical systems.
   • The vehicle functions normally—just without the aux battery.
3. ESS Still Works (Sometimes):
   • In many cases, the ESS system will still operate depending on the main battery's health and charge.
   • Or, if it’s disabled (via a programmer or button memory mod), it won’t trigger any faults, and the system is still intact.
4. No Permanent Modification (if done properly):
   • A bypass can be done with a simple jumper cable or bypass kit, without cutting or damaging the original wiring.
   • It’s a reversible change, which means it can be undone if needed.

Why Warranty Denial Is Unlikely

1. Magnuson-Moss Warranty Act (U.S.):
   • This federal law states a dealership must prove a modification caused the problem to deny warranty coverage.
   • Just bypassing the aux battery doesn’t damage other systems—so it’s hard for a dealer to deny unrelated warranty claims.
2. Dealers Know About This Problem:
   • Many Jeep service departments are familiar with the aux battery issue—it’s a common failure point.
   • Some even unofficially recommend bypassing or removing the aux battery, or have done it themselves under warranty repairs.
3. Bypass Often Used as a Diagnostic Step:
   • Bypassing is sometimes used by techs to diagnose whether a dead aux battery is the root cause of no-start or ESS issues.
   • That makes it hard for them to argue that the bypass caused a problem.

Caveats / Risks

• If improperly done, a bypass could cause:
  • Overload of the main battery
  • Short circuits or poor connections
• Some dealers may still try to push back on warranty claims if they see signs of DIY electrical work—so it’s best to be clean, reversible, and informed.
• Bypassing doesn’t address the root design flaw—it just eliminates one failure point.

Summary

Bypassing the Jeep JL’s aux battery is:

• A common fix for ESS problems
• Generally safe and non-invasive
• Easily reversible
• Not known to void warranty, unless proven to cause specific issues

As long as it's done cleanly and the main battery is in good shape, it's a practical solution many owners choose—with little risk of warranty trouble.

 

[siggy]

Curious, has anyone heard of or experienced a dealership denying service on a factory dual AGM battery JL simply because the owner presented the vehicle with a disconnected Aux battery and Fuse 42 setup (or, effectively the same thing, a fused jumper from N1 to N2 in the PDC)? TIA

Never experienced it, but would fully expect a dealership to turn you away. In fact, they should. That would be the same as you putting on a lift and then bringing it in for death wobble.

 

[Wbino]

I pretty sure the dealer denied service because the OP gave them a 900 word memo.

 

[Terrymo]

I pretty sure the dealer denied service because the OP gave them a 900 word memo.

Like Cliff Clavin from Cheers. There’s no simple, short answer.

 

[AndySpill]

Never experienced it, but would fully expect a dealership to turn you away. In fact, they should. That would be the same as you putting on a lift and then bringing it in for death wobble.

Siggy, I respectfully disagree with both the likely outcome and analogy. I think most dealers would neither deny warranty or fee for service coverage for this battery bypass

Let me offer you an analogy you can disagree with if you like but I think more on point.

You have a clearly defective tire (an ESS system that works poorly and you don't use). You change it out for the spare, drive into the dealer, and get turned down for that bad tire's replacement because you "modified things."

Do know that I clearly agree with you though that owners should be denied service for a death wobble unless it can be reproduced in the vehicle's stock and un-lifted state.

 

[Wbino]

Like Cliff Clavin from Cheers. There’s no simple, short answer.

I liked Cliff, it was that uppity Frazier that was a dic.

 

[AndySpill]

I pretty sure the dealer denied service because the OP gave them a 900 word memo.

Here's what separates us @Wbino. Assuming you're not stupid, I don't think you'd say the above to anyone you felt this way about, particularly if bearing similar stature to Alan Richardson.

I on the other hand conduct myself here no differently that when face to face (provided nobody's holding a weapon in my general direction.)

Of course my conversations with service techs are as terse as humanly possible. It's not only the right thing to so (see my prior sentence), it serves my interest in keeping focus on my issues, none of which have been the issue I originally raised here. As mentioned, I run both batteries stock.

What about that 900 word memo champ were you forced to read, thought was off point, couldn't be blocked by your choice?

Here's some music to compose your answer to that question to.

 

[Wbino]

Here's what separates us @Wbino. Assuming you're not stupid, I don't think you'd say the above to anyone you felt this way about, particularly if bearing similar stature to Alan Richardson.

I on the other hand conduct myself here no differently that when face to face (provided nobody's holding a weapon in my general direction.)

Of course my conversations with service techs are as terse as humanly possible. It's not only the right thing to so (see my prior sentence), it serves my interest in keeping focus on my issues, none of which have been the issue I originally raised here. As mentioned, I run both batteries stock.

What about that 900 word memo champ were you forced to read, thought was off point, couldn't be blocked by your choice?

Here's some music to compose your answer to that question to.

Didn't you just start this thread that was immediately blocked by the mods?

https://www.jlwranglerforums.com/forum/threads/forum-personality-nuance.154733/

 

[THAW]

You have a clearly defective tire (an ESS system that works poorly and you don't use). You change it out for the spare, drive into the dealer, and get turned down for that bad tire's replacement because you "modified things."

Terrible analogy. Using the spare for it's intended purpose is not remotely the same as bypassing the intended purpose of electrical components (because the owner is dissatisfied with the design).

 

[AndySpill]

Didn't you just start this thread that was immediately blocked by the mods?

https://www.jlwranglerforums.com/forum/threads/forum-personality-nuance.154733/

What on earth is your point? I pointed to an observation about Jeepers not even of my own creation, and others chimed in some harsh stuff, and only then was the thread closed, of course not of my doing.

Maybe if I responded back to them you'd have a point.

Anyway, getting back to my question about

What about that 900 word memo champ were you forced to read, thought was off point, couldn't be blocked by your choice?

 

[AndySpill]

Terrible analogy. Using the spare for it's intended purpose is not remotely the same as bypassing the intended purpose of electrical components (because the owner is dissatisfied with the design).

...says the man who feels there's nothing wrong with with ESS events on one battery.

So what exactly was the intended purpose of those electrical components Foster if by your own ideals that ESS battery isn't needed even if people are running ESS events.

...to help cold crank the engine?

(Why won't you stay down?)

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