Aux Battery Died, Weird Results When Doing Fuse 42 / Aux Battery Disconnection

[foxwalkhq]

I have a 2022 Jeep Gladiator and the other day it wouldn't start.. My jump starter is broken so I called roadside assistance to jump it. It started I ran it for 30 minutes and then I drove doing errands, leaving the engine running at each stop.

The next day, it wouldn't start again.

It has the same symptoms as the aux battery dying and draining the main battery. I've seen the posts here, and so what I did was I pulled fuse 42 out of the fuse box. It is definitely the right fuse. I've seen videos of people do it, I saw it in the diagram etc.

Then I removed the black ground cable from the long bolt on the right of the metal plate that the other black cable is connected to. I wrapped it in electrical tape, and realized I had no power at all.

Then I learned that the method I saw on here and was doing is for (June) 2021 and earlier Gladiator models.. For June 2021 and higher the OTHER cable is the aux battery connection.. So I remove the other cable that has the metal plate and the long bolt on it, wrap IT in electrical tape, and then I attach the other ground cable wherethe one with the plate was and secure it with the smaller 13mm bolt.

Everything seemed fine. When I tried to start the car it still wouldn't start, but nothing out of the ordinary (you'll see why I say this later). I ordered a new jump starter. A highly rated one on multiple review sites and it has a lot of power.. It can jump 20 vehicles on a single charge.

Then I connect the jumper as shown in the instructions. red clamp to + battery terminal, black clamp to - terminal. I know that they say you're not supposed to connect the black directly to the battery, but to the chassis but that's what the instructions said, so that's what I did.

I went in, and this is where it gets weird af. I press the start button. It says "Key fob not recognized." I take the key fob out of my shorts.. huh? I press start. "Key fob not recognized" .. The third time it said "press button on key fob to start" Then I pressed the unlock button.. doors clicked unlocked.. I press start.. doesn't start.

Now messages start coming back "Sway bar disconnect error" "Please service power steering" .. And when I try to turn the car off (It's currently in Run, but not started) it says "Vehicle is not in park." It would not turn off.. and the vehicle was definitely in park.

I thought maybe if I pull the orange loop that puts the truck in neutral when it's turned off and let it go, maybe it would see it's in park. I pull the orange loop, and I see "Please service transmission" and when I let go of it, the message goes away.

So I go and I remove the negative ground wire from the battery. Wait a few minutes. You know the defacto "turn it off turn it on again." I thought hard rebooting the system might fix it.

Nope. Same problems.

So then I'm like fine.. Whatever I'm sick of this. And I replace fuse 42, and I put everything back the way it was originally.

Get in the truck. Press start. Truck starts effortlessly.. No lights of any kind except the CEL which is due to a "low voltage" code that hit (see below)

WTF.

I'm guessing that my new super jump starter probably charged the battery enough for it to start.

Now I dunno if the aux battery is charged too or what not.. As far as the issues.. All I can think is maybe they made some changes in 2022 where the F42 / removing the aux battery's negative cable doesn't work?

The thing is, I really need money now.. and I'm about to put a bunch of stuff on ebay, and I don't wanna deal with having to take my car to the dealer and wait forever for the warranty replacement, so I just wanted to disconnect the aux battery if only temporarily.

I also got a check engine light with some codes.. The first time this happened and the tow guy jumped it, I got a "Low voltage" code which is to be expected.

I'm gonna go out now and read the code and see if it's the same or different. Yeah, same code "Low voltage" .. Probably from when the battery was dead.

Each time that the truck wouldn't start the voltage in the instrument cluster read ~7 volts.

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[Mr._Bill]

Disconnect both batteries and measure the voltage level of each one. Anything reading below 12.2 is suspect. Separately charge each battery and see what happens. Fully charged should give a reading of 12.8 volts.

It's very likely the Main battery is the problem. The two batteries are paralleled together all the time. To determine which one is the problem, the grounds have to be disconnected and each battery checked separately.

 

[ShawnwFL]

Mine did very similar things when the aux battery failed. Randomly wouldn’t even try to start, then randomly starting no problem. I got “diesel pre heat in progress” and “water in fuel” messages (it was 80 degrees outside when this happened).

when dealer ran codes it showed no history of any codes being thrown, if I hadn’t had taken pics of the error messages they would not have known anything was wrong, because of course it started fine at the dealer.

anyway, they checked fuel filter and no water was found. I showed them a thread on here about aux battery failures and crazy warnings popping up and convinced them to Chex the aux battery, it showed 0 V. Dead as a doornail.

they replaced the aux battery under warranty and I tried to convince them to replace the main too but it was reading “fine” so they said they couldn’t do it under warranty. Jeep ran fine for 6 months then the main battery failed. I feel you are about to make a similar journey.

 

[Puch]

?

 

[foxwalkhq]

My 20 and 21 had almost the exact problem and I took the same steps as you.
truck wouldn’t start when one of the two batteries were disconnected. Only started if both were connected at the same time.
I replaced the main, eliminated the aux, and pulled 42. It’s been working perfectly. I still choose to push the ESS because that system is worthless.

I sometimes forget to push it and smoke comes out everywhere and lights flash and the wheels lock up, but no flames yet so I guess it’s okay. ?

That system sucks..

What I'm probably gonna do unless someone can tell me exactly what the problem is, I'm going to just have the dealer replace whatever battery is bad.. I'm guessing it's under warranty still..

I've only had it for a year.. Does warranty start at purchase or from date of manufacture? (I bought it new)

For now my new jump charger is great. I will jump it with that if I have issues and just leave engine running until I get all this stuff sold and shipped on ebay.

When I get more money I'll get a Taser so I can disable to auto stop/start.

 

[Mr._Bill]

Warranty starts at purchase. That's one reason why it's important to make sure the mileage on the sales contract matches the truck.

Many people do not like ESS, for various reasons, but it cannot be disabled. You can add a device to prevent ESS from turning off the engine, and the Tazer is the most expensive option for that.

Be sure to reconnect the cables and restore it to factory condition before taking it to the dealer.

 

[ShadowsPapa]

It has the same symptoms as the aux battery dying and draining the main battery. I've seen the posts here, and so what I did was I pulled fuse 42 out of the fuse box. It is definitely the right fuse. I've seen videos of people do it, I saw it in the diagram etc.

How do you know it wasn't the main battery going bad - and even draining the aux.
that bit about the aux is, well, won't go there yet again.
Don't assume. Check. The main battery can fail and go bad as often.
A bad battery also doesn't always take down the other Otherwise tractor owners who have 2 or 4 batteries would always have to replace all of them when one failed.

Do as advised - disconnect the batteries, charge each, check the voltage.

It's when people go by the internet "the aux always goes bad and............." and assume that's correct because enough people repeat it that things get tangled and no real troubleshooting is done.

Do what @Mr._Bill suggested.

 

[Lunentucker]

You got all of the craziness because the battery didn't initially have enough charge to run everything. All of the weird error messages and lights are typical of a failing or depleted battery.
Leave it as it is and fully charge the main.
If that's working, go head and pull the fuse again and see what happens after the battery is back up to par.
You should have also lost things related specifically to your build and subscriptions in U-Connect, but they come back over a few hours - overnight at worst.

 

[kevman65]

If you didn't say you were short on cash I'd advise you to skip the dealer and the batteries they will use.
But since you did, utilize the warranty for now. When you can, get better batteries for less money than OEM.

OEM are hit and miss. Mine are still factory and 4 years old. Others have had them replaced in less than 6 months.

 

[ShadowsPapa]

You got all of the craziness because the battery didn't initially have enough charge to run everything. All of the weird error messages and lights are typical of a failing or depleted battery.
Leave it as it is and fully charge the main.
If that's working, go head and pull the fuse again and see what happens after the battery is back up to par.
You should have also lost things related specifically to your build and subscriptions in U-Connect, but they come back over a few hours - overnight at worst.

Yeah, that 7 volt bit on the screen was a huge tell.

He absolutely needs to charge the battery/batteries and see how things shake out. Even the dealer won't replace batteries at only 7 volts without first charging them so they can run their tests.

 

[@californiajeeping]

Don’t remove any fuses. Run the aux power up to the main. Then take the aux ground and run it to the fender. Everything works perfectly and you get much more stable voltage. If you use ESS occasionally your radio will reboot. Like 1 out of 10 times.

 

[biodiesel]

Does the Gladiator EcoDiesel come factory with an AGM battery? Ram put the same AGM battery in the 4th (2014 - 2019) and 5th gen (2020 - 2023) EcoDiesel, which seems to be lasting 8 - 10 years for many folks, me included. I'm now curious what battery Jeep is using in the Gladiator EcoDiesel.

 

[ShadowsPapa]

Does the Gladiator EcoDiesel come factory with an AGM battery?

Yes.

The crank battery in the JT is roughly the same battery as the 12 volt battery in the Jeep 4xe.
And guess what 4xe owners complain of - 12 volt battery failures after any where from a couple of months to a couple of years.
And guess what the 4xe does not have - a smaller aux battery. So the bit of the aux killing the main doesn't cut it on a 4xe. People in those forums gripe about the short life of the 12 volt batteries. (I've also noticed that the voltage on those drops a fair amount when they sit a few days, and the DC-DC charging system doesn't do a great job charging them back up)

 

[Mr._Bill]

Does the Gladiator EcoDiesel come factory with an AGM battery? Ram put the same AGM battery in the 4th (2014 - 2019) and 5th gen (2020 - 2023) EcoDiesel, which seems to be lasting 8 - 10 years for many folks, me included. I'm now curious what battery Jeep is using in the Gladiator EcoDiesel.

All Gladiators come with AGM batteries. They appear to get cooked under the hood. The average life expectancy is about three years.

 

[ShadowsPapa]

From the book "Rube Goldberg electrical wiring 101"

Then take the aux ground and run it to the fender. Everything works perfectly and you get much more stable voltage.

Running the aux battery ground to the fender is going to make things worse. Why would anyone take the battery grounds and separate them by another cable, an extra connection and additional voltage drop? The grounds for batteries should be as close as possible electrically to the ground of the alternator (and the rest of the electrical systems)
Moving that ground flies in the face of all logic electrically, makes no sense and has no purpose. The two batteries are grounded together for a reason - an electrical reason, not to save a dime. To introduce a drop between the two is adding troubles.
That "tip" sounds just like the tech who said he could fix my dropping voltage by moving my winch ground from the battery to the fender - I laughed at the service advisor and said they were totally full of it because they are both battery grounds, just that now the winch ground had to go through another smaller ground cable and extra voltage drop.

Don’t remove any fuses. Run the aux power up to the main.
If you use ESS occasionally your radio will reboot. Like 1 out of 10 times.

Why will the radio reboot? This is basically the same as pulling F42 except you are bypassing the PCR by running a wire from the aux hot to the main battery. They are already connected together through the PCR.
Pulling the fuse may cause the ESS to stop working after about 6 ESS cycles because the voltage detected during start is identical to the main, since the PCR can't open.
No one has ever had a radio reboot from that because the radio isn't seeing anything different at all. It's still getting the power it needs.

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