Another Aux Delete Question.

[JTenn]

There's too much information (misinformation) out there regarding the aux delete. This whole process seems very simple but yet the results seem to vary depending on who is writing the thread. It doesn't help that FCA decided to change the grounding on the 21's and up which just adds to the confusion. So here is my experience/question.

The main battery in my wife's 20 Overland finally gave it up. I decided to do the aux delete while installing the new battery.
1) Disconnected the dead main neg from the post.
2) One of the added aftermarket accessories under the hood had an led still lit up. (Pulling power from the aux).
3) Disconnected the larger of the 2 negative cables from the terminal.
4) Accessory led went out.
5) Taped up and isolated the now disconnected larger negative cable.
6) Removed f42 fuse.
7) installed new main battery.
Everything works as normal including ESS. My question is what would happen if you disconnect the wrong negative cable? I am under the impression that doing the aux delete disables ESS. But it still works as normal even though one of the negative cables is isolated and disconnected. The ESS working as normal is what I'm confused about. How could the truck be acting normal with one of the negative cables completely isolated and f42 fuse removed? I will put a meter on both ends of that negative cable to check continuity this weekend. I think regardless of year model, the sure way to delete the aux is to physically remove it and pull the f42 fuse. Sorry to throw out yet another aux delete thread but I truly want to understand.

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[KQL]

Correct, you did not disable ESS, you disconnected the aux battery and are preventing the system from checking its voltage independently (removal of F42 fuse). Typically people that do the Aux delete combine it with some sort of ESS disable approach. Use the disable button in the dash, Taser, standalone memory device that remembers the state of the button on the dash, I think there is also a hood switch disconnect approach.

 

[Puch]

?

 

[sharpsicle]

My question is what would happen if you disconnect the wrong negative cable?

Nothing. Literally nothing, as you'd have no power going anywhere. You'd have a dead truck as there's no chassis ground then.

I am under the impression that doing the aux delete disables ESS. But it still works as normal even though one of the negative cables is isolated and disconnected. The ESS working as normal is what I'm confused about.

You aren't disabling a system. You're removing a battery from a set of batteries. Everything else still functions. In fact, the steps you are taking (removing fuse 42) is tricking the system into thinking the aux battery is still there, so you should expect no changes in function.

How could the truck be acting normal with one of the negative cables completely isolated and f42 fuse removed?

That's just the aux negative. It goes to the main negative post, because from there both go to chassis ground. That chassis ground remains unchanged. Removing the fuse prevents the truck from separating the two batteries on ESS events. Since the batteries are in parallel 100% of the time with the fuse removed, removing one just reduces overall capacity of the battery system, rather than changing the function or configuration.

I hope this brings some clarity to your concerns.

 

[JTenn]

Correct, you did not disable ESS, you disconnected the aux battery and are preventing the system from checking its voltage independently (removal of F42 fuse). Typically people that do the Aux delete combine it with some sort of ESS disable approach. Use the disable button in the dash, Taser, standalone memory device that remembers the state of the button on the dash, I think there is also a hood switch disconnect approach.

Thanks for explanation. This makes sense to me. I do have a tazer installed but it's her truck and she can decide if she wants to use it or not.

 

[JTenn]

Nothing. Literally nothing, as you'd have no power going anywhere. You'd have a dead truck as there's no chassis ground then.

You aren't disabling a system. You're removing a battery from a set of batteries. Everything else still functions. In fact, the steps you are taking (removing fuse 42) is tricking the system into thinking the aux battery is still there, so you should expect no changes in function.

That's just the aux negative. It goes to the main negative post, because from there both go to chassis ground. That chassis ground remains unchanged. Removing the fuse prevents the truck from separating the two batteries on ESS events. Since the batteries are in parallel 100% of the time with the fuse removed, removing one just reduces overall capacity of the battery system, rather than changing the function or configuration.

I hope this brings some clarity to your concerns.

Thanks you sir. These explanations all make sense and yes they bring clarity.

 

[HopSlammer]

@JTenn
Good thread/post you started, I was looking for these answers too.

 

[JTenn]

@JTenn
Good thread/post you started, I was looking for these answers too.

Thanks. I know some topics get beat to death and this one is no exception. These replies make complete sense to me though. Hopefully someone will stumble across this some day and will help them out too. I figured I would get beat up for even asking the question but I guess I forgot most of the folks here are genuinely good folks, ? I really do appreciate the straightforward descriptive answers.

 

[Maximus Gladius]

I’ve taken a little different approach to this conundrum. The big question for me has been if the primary problem to this AUX battery thing is that mopar batteries are sub par, short life, they become parasitic to each other, why not turf them and upgrade the batteries?
The system isn’t flawed, the batteries are.

The system that is tied to the aux battery was designed for a reason. I’d have to reach way down somewhere and pull out some faith that the engineers that designed that system had a divine inspired reason that made some sense to make it a thing. So,…one side of me said, keep the system as designed and upgrade the aux battery and while I’m at it turf the main and go all out on the biggest ass battery that will fit the main compartment.

The other part of me said, I have NEVER in my life driven a vehicle that needed two batteries to function and I have also NEVER had to wire in an AGM tender to plug in every 4 days to bring my crap ass Mopar batteries up to charge so I have the next 4 days of some confidence my truck will start.

I have also NEVER had a vehicle so packed with electronics which is where I believe the aux system was engineered to protect. They just didn’t think that that system needed reliable batteries to run it and that’s where the flaw is.

So while we are on this voyage, some yank the aux and fuses and run with it and others just replace the batteries for better ones, I’ve decided to upgrade both.

For my main I went all out for the AGM Optima DH7 Yellow Top, deep cycle/starter. Crank AMPS (1000) Cold Crank AMPS (880).

JUST JEEPS suggested their brand of choice for the aux is AC Delco. I called my local Lordco Auto, (an AC Delco retailer) and they suggested the MagnaSport AGM over the AC Delco. It has 230 Cold Crank over the AC Delco 200 cc.

Haven’t installed yet as I’m making sure both batteries are 100% charged up with my AGM tender. (Side Note: don’t assume brand new batteries are 100% charged off the shelf, they aren’t. The Optima battery was @ 12.7v and the aux was @ 12.1v) Load test them before batteries go in. If your AGM is under 12.5v, return it for one that hasn’t dropped so low.

Lordco is replacing the aux on Monday (aug 14) and I charged the Optima to 13.2v.

 

[ShadowsPapa]

Thanks. I know some topics get beat to death and this one is no exception. These replies make complete sense to me though. Hopefully someone will stumble across this some day and will help them out too. I figured I would get beat up for even asking the question but I guess I forgot most of the folks here are genuinely good folks, ? I really do appreciate the straightforward descriptive answers.

The problem comes in when someone with a 2020 looks at what someone with a 2021 or 2022 does and has troubles because Jeep literally swapped those black ground cables around after 2020 model year.
For 2020 the top of the black cables was the aux battery ground. Simple, take it off, wrap it up.
For 2021 and later, the top of the two is the MAIN battery ground. The bottom one with the larger flat end and stud(s) is the aux battery ground.

As already explained, all pulling the F42 fuse does is prevent an error light on the dash, nothing more. It prevents the relay that triggers the opening of the PCR (which is the larger relay by the aux battery) from opening. the PCM sends the signal to the relay saying open the PCR so I can check aux battery level. It assumes it has opened, sees only the main battery voltage and life goes on. It is said that ESS will only function a limited number of times this way but I can't say how often that's been verified.

Red arrow points to IBS
2020 indicates the AUX battery ground cable for that year
2021+ indicates the AUX battery ground cable for 2021 and later model years.

 

[ShadowsPapa]

he other part of me said, I have NEVER in my life driven a vehicle that needed two batteries to function and I have also NEVER had to wire in an AGM tender to plug in every 4 days to bring my crap ass Mopar batteries up to charge so I have the next 4 days of some confidence my truck will start.

You likely don't own certain models/years BMW or Chevrolet or certain others, then. it's not an FCA invention, they just stole the idea.

My truck may sit for 2, 3 or 4 days undriven but when it's driven, it's enough to mostly keep things up. I charge now and then but these seem to be doing well so far.
2022 voltages seem to run different than my 2020 ever did - did FCA make changes or am I imagining changes that never happened? So far, this one has never failed to be high enough to operate ESS - it's always worked. Granted, it's only a bit over a year old but still......... I see battery voltages higher than my 2020 had.

They just didn’t think that that system needed reliable batteries to run it and that’s where the flaw is.

So while we are on this voyage, some yank the aux and fuses and run with it and others just replace the batteries for better ones, I’ve decided to upgrade both.

For my main I went all out for the AGM Optima DH7 Yellow Top, deep cycle/starter. Crank AMPS (1000) Cold Crank AMPS (880).

Again - explain why the 4xe is known for losing 12v batteries? There is no aux system, just one main battery. It's crap batteries, but it's an industry trend according to car people i've talked to. Getting 4 years out of batteries these days is a miracle. Even my last premium NAPA battery lasted about 4 years. In the past I'd have gotten 6+

I'm more interested in amp hours than anything else - High CCA is fine, but I look for the marathon abilities and the ability to survive cycling since if these aren't driven often enough far enough fast enough, they never fully charge the batteries.

 

[JTenn]

The problem comes in when someone with a 2020 looks at what someone with a 2021 or 2022 does and has troubles because Jeep literally swapped those black ground cables around after 2020 model year.
For 2020 the top of the black cables was the aux battery ground. Simple, take it off, wrap it up.
For 2021 and later, the top of the two is the MAIN battery ground. The bottom one with the larger flat end and stud(s) is the aux battery ground.

As already explained, all pulling the F42 fuse does is prevent an error light on the dash, nothing more. It prevents the relay that triggers the opening of the PCR (which is the larger relay by the aux battery) from opening. the PCM sends the signal to the relay saying open the PCR so I can check aux battery level. It assumes it has opened, sees only the main battery voltage and life goes on. It is said that ESS will only function a limited number of times this way but I can't say how often that's been verified.

Red arrow points to IBS
2020 indicates the AUX battery ground cable for that year
2021+ indicates the AUX battery ground cable for 2021 and later model years.

Clear as mud, lol. Thanks Shadows. This picture will further help clarify the difference for others. The one for 2020 indicated in your Pic is the one I isolated.

 

[ShadowsPapa]

Clear as mud, lol. Thanks Shadows. This picture will further help clarify the difference for others. The one for 2020 indicated in your Pic is the one I isolated.

Yeah, that's the correct one for your 2020.

 

[Dryfly24]

The problem comes in when someone with a 2020 looks at what someone with a 2021 or 2022 does and has troubles because Jeep literally swapped those black ground cables around after 2020 model year.
For 2020 the top of the black cables was the aux battery ground. Simple, take it off, wrap it up.
For 2021 and later, the top of the two is the MAIN battery ground. The bottom one with the larger flat end and stud(s) is the aux battery ground.

As already explained, all pulling the F42 fuse does is prevent an error light on the dash, nothing more. It prevents the relay that triggers the opening of the PCR (which is the larger relay by the aux battery) from opening. the PCM sends the signal to the relay saying open the PCR so I can check aux battery level. It assumes it has opened, sees only the main battery voltage and life goes on. It is said that ESS will only function a limited number of times this way but I can't say how often that's been verified.

Red arrow points to IBS
2020 indicates the AUX battery ground cable for that year
2021+ indicates the AUX battery ground cable for 2021 and later model years.

Oh boy - here we go. . .

I wrapped up the neg cable and pulled the fuse. Why the hell am I still getting an error light?! ??

 

[Silversport23]

Ok guys here my question, did these systems change on the 23 models? I’m curious because I only drive my glad about once of twice a month and have never had an issue. Now to be honest my truck has 1100 miles. Every other vehicle I own has an XS power AGM battery and some have multiple with the exception of my trail rig with a 16 volt brale battery. I have the 7/70 bumper to bumper on the Jeep so I likely won’t mess with the battery much, just curious if I should be using a tender

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