A! Yellow Warning Light Reset

[Terrymo]

People hang on to batteries on this forum either because of selective penny pinching or bragging rights. I can’t quite figure out the reluctance to swap in a reliable battery preemptively. You don’t wait to run completely out of gas before filling up each time, or for your tire to have a blow out before replacing it hopefully. The amount of hand wringing and debate over an item that cost less than $200 is amazing.

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[AndySpill]

The opposite. The A will stay displayed. Honestly, I don't even notice it anymore. The whole point of the bypass is increased long-term reliability as well as saving money by no longer needing to replace the aux battery every several years.

This hasn't been my experience or understand on how things work.

At pre cold-crank, if an adequately powered Aux battery, or what the vehicle thinks is the Aux battery is found, a preexisting ESS off light in the dash will turn off.

As stated prior, if the Aux has been bypassed and Fuse 42 pulled, that Aux battery test will actually be of the main battery.

@AnebuR based on what you are describing, assuming you've bypassed the Aux battery as described, if you're still getting the ESS off light in the dash I would be inclined to load test your main battery.

 

[Bob Burd]

The opposite. The A will stay displayed. Honestly, I don't even notice it anymore. The whole point of the bypass is increased long-term reliability as well as saving money by no longer needing to replace the aux battery every several years.

This isn't true. If you remove the aux battery and fuse 42, the A will not stay lit unless you have an underlying issue.

 

[andy29847]

This isn't true. If you remove the aux battery and fuse 42, the A will not stay lit unless you have an underlying issue.

Not true. Removing the aux battery and fuse f42 (for the power control relay) does not affect stop/start. The stop/start light, AKA Avenger light, can be triggered by many things. A bad battery is the most likely trigger. The article at this link lists other:

Stop/Start Unavailable Service Stop/Start System: 5 Tips To Fix The Error

 

[ScotM]

Not true. Removing the aux battery and fuse f42 (for the power control relay) does not affect stop/start. The stop/start light, AKA Avenger light, can be triggered by many things. A bad battery is the most likely trigger. The article at this link lists other:

Stop/Start Unavailable Service Stop/Start System: 5 Tips To Fix The Error

Boy that reads like AI. I read the whole repetitive thread, and although the hood sensor can be a culprit, the most likely problem is the battery or plural batteries . just keep it simple, and eliminate the useless aux battery, remove fuse 42, load test the main battery, replace if required , if that doesn’t fix it, move on to the less likely culprits. Having the avengers light is not a normal condition, and can be eliminated.

 

[AnebuR]

For the record, I did the F42/bypass shortly after getting my Jeep back from the service department with two new batteries while still under warranty. Regardless, I've driven around for years now without any apparent issue on the same main battery or anything else for the matter.

 

[ScotM]

Not true. Removing the aux battery and fuse f42 (for the power control relay) does not affect stop/start. The stop/start light, AKA Avenger light, can be triggered by many things. A bad battery is the most likely trigger. The article at this link lists other:

Stop/Start Unavailable Service Stop/Start System: 5 Tips To Fix The Error

Boy that reads like AI. I read the whole repetitive thread, and although the hood sensor can be a culprit, the most likely problem is the battery or plural batteries . just keep it simple, and eliminate the useless aux battery, remove fuse 42, load test the main battery, replace if required , if that doesn’t fix it, move on to the less likely culprits. Having the avengers light is not a normal condition, and can be eliminated.

 

[mwilk012]

Boy that reads like AI. I read the whole repetitive thread, and although the hood sensor can be a culprit, the most likely problem is the battery or plural batteries . just keep it simple, and eliminate the useless aux battery, remove fuse 42, load test the main battery, replace if required , if that doesn’t fix it, move on to the less likely culprits. Having the avengers light is not a normal condition, and can be eliminated.

Except it won’t be eliminated by doing what you just described. It will constantly have a fault.

 

[AVGeek99]

The opposite. The A will stay displayed. Honestly, I don't even notice it anymore. The whole point of the bypass is increased long-term reliability as well as saving money by no longer needing to replace the aux battery every several years.

Umm... No. If you do the Aux delete correctly, there are no lights displayed on the dash. I did this with my 2021 and again with my 2025.

Disconnect the Aux battery line running to the Negative post on the main battery. This is the smaller of the tow lines going to the negative post. At least on late 2021 builds and newer, it is also the one that has the additional accessory post attached. Pull fuse 42. If you do both of those things you will have effectively deleted the Aux battery and will not have the Yellow A! warning.

If you have the Yellow A! warning light, then you have something else going on.

 

[AVGeek99]

Not true. Removing the aux battery and fuse f42 (for the power control relay) does not affect stop/start. The stop/start light, AKA Avenger light, can be triggered by many things. A bad battery is the most likely trigger. The article at this link lists other:

Stop/Start Unavailable Service Stop/Start System: 5 Tips To Fix The Error

No one has said anything about ESS. You are right that removing the Aux and pulling fuse 42 doesn't eliminate, or really have any impact on ESS. It just eliminates the issues associated with the Aux battery. The issue is the Yellow A! warning light. It will not illuminate simply by executing a correct Aux delete. If it is illuminated there is some other underlying issue.

 

[andy29847]

Peace of mind at last! Replaced main battery with a premium H7/Group 94 battery | Jeep Gladiator (JT) News, Forum, Community - JeepGladiatorForum.com

 

[andy29847]

No one has said anything about ESS. You are right that removing the Aux and pulling fuse 42 doesn't eliminate, or really have any impact on ESS. It just eliminates the issues associated with the Aux battery. The issue is the Yellow A! warning light. It will not illuminate simply by executing a correct Aux delete. If it is illuminated there is some other underlying issue.

The yellow A (Avenger) light is all about ESS.

 

[Jebiruph]

The yellow A (Avenger) light is all about ESS.

Yes, but it can be indicating that ESS was disabled due to an underlying issue not directly related to ESS like misfires.

 

[AndySpill]

For the record, I did the F42/bypass shortly after getting my Jeep back from the service department with two new batteries while still under warranty. Regardless, I've driven around for years now without any apparent issue on the same main battery or anything else for the matter.

It is possible @AnebuR that there is some other issue causing the ESS off light to appear in the dash for you.

And it is all sadly possible, that the one or both of the two new batteries that the dealer installed for you are defective.

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I'm reading a bunch of posts in this thread about how the Aux battery bypass eliminates, or is unrelated to, or even produces the ESS off light in the dash. While all of these 3 conditions may occur as a result of a bypass, the bypass doesn't cause them.

Rather, on dual AGM battery JLs, the pre-crank test happens, all unknown to the vehicle's diagnostics, against the Aux battery in the factory configuration, and the main battery in the bypassed one. In either of these cases, if the tested battery (whatever battery that is) proves inadequate it can trigger the ESS off light illuminating in the dash.

If the ESS off light turns off as a result of a bypass, most likely your main battery has passed this test that your Aux could not. If it goes on, the converse may be true. And if the ESS off light is not illuminated before or after the bypass, both batteries are probably good.

 

[AVGeek99]

The yellow A (Avenger) light is all about ESS.

Actually, I believe there are several things that will cause the yellow A (Avenger) light, but yes it is typically somehow related to ESS. I am not disputing that one bit.

I was responding to @AnebuR who was saying the yellow A (Avenger) light is normal when you do an Aux delete. I was simply saying that when done correctly, an Aux delete will not trigger the yellow A (Avenger) light, and that if it is illumnated, then there is something else wrong.

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