Weird JL Behavior - ? Aux battery symptom

[ahole4sure]

My daughter has a 2018 JL (Wrangler). Over last 6 months she had some crazy issues. Unfortunately I live in WV and she lives in FL.

First car had some issues with the "brake" light flashing on and off (not completely sure if she meant the parking brake light or the ABS lights). Ultimate car would not start one day and had to be towed. The mechanic replaced the main battery and told her that the Aux batttery was bad too but it was far too difficult to replace and said he would "have to take the car completely apart" (lol) to replace.

Worked fine for several months apparently with the ??added bonus?? (from her perspective that she didn't have to mess with the ESS because "it didn't work anymore.

Then on a 3 hr trip from west FL to east FL all interstate she notice the brake warning lights flashing on and off and apparently the screen may have gone off and then back on while driving.

Most recently after getting back home to west FL without issue noticed that the Jeep would just shut off while driving in parking lots (like less than 25 mph or so). She said that she just hit the main Start button and the engine would start right back up.

At first worried that it could be the TIPM - ordered one from RockAuto and apparently the wrong size or part. But as we are discussing things I am thinking that it might ALL just be due to the dead Aux Battery ...

Thoughts?

If so does anyone know - if the Aux battery is replaced and all is fixed - can I "turn off" the ESS system with AlfaOBD ( I already have for my 2018 Dodge Ram truck)

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[aldo98229]

I honestly do not understand why dealers make this such a painful process.

Replace both batteries and it will fix everything.

If the dealer doesn’t want to do it, recruit her best friend/boyfriend/fiancé/husband to do it for her.

Two years ago I replaced both batteries following the steps on this video. Haven’t had any more electronic/electrical issues since.

 

[aldo98229]

PS - she doesn’t need to buy any expensive batteries either. Auto Zone and O’Reilly’s own store brands are made by the large battery manufacturers; they are good quality.

 

[Reinen]

A major function of ESS is that it alerts you to battery issues because it's the first thing to stop working with bad batteries, but it's non-essential.

As @aldo98229 said, replace both batteries and all will be resolved. And not at wherever the Main battery was replaced. That is a scary clueless mechanic. Yes, both. By now the bad Aux battery has damaged the Main battery and reduced it's lifespan, which in turn will reduce the life of the replaced Aux battery, and so on in an endless cycle. This is why if one battery is bad you always replace both Main and Aux at the same time.

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