Aux bypass not working

[Mr._Bill]

sounds like the safest bet is to replace both battteries

That's what I would suggest. Add a battery maintainer and you should be able to get close to four years out of the new ones.

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[RIPLER]

You will still get the error until you do a few drive cycles. Eliminating the aux battery and the fuse does not disable the start stop feature, it only eliminates the aux battery. Having a weak main battery will also produce this error. I don't understand why everyone says to replace both batteries at the same time, it's waste of money. I've replaced my main battery once and my aux battery is over 5 years old and still working as intended

 

[arosen1997]

This is how I charge mine when it sits for a few days (and it's been sitting a lot since I'm not really supposed to be driving with new meds and med conditions)

This contraption is fantastic

 

[Mr._Bill]

You will still get the error until you do a few drive cycles. Eliminating the aux battery and the fuse does not disable the start stop feature, it only eliminates the aux battery. Having a weak main battery will also produce this error. I don't understand why everyone says to replace both batteries at the same time, it's waste of money. I've replaced my main battery once and my aux battery is over 5 years old and still working as intended

Replacing both batteries at the same time is easier for most, and eliminates having to go through the hassle again in the near future. The Aux battery can have a longer life, but it doesn't always. On my first truck, the Main died at 3.5 years and the Aux lasted another six months. Many have reported the Aux going first. The environment, and how the truck is driven, have a big impact on battery life.

 

[gonemad]

I’m brand spankin’ new to the whole Jeep auxiliary battery thing, so bear with me.

When you start getting warning signals of a weak battery, assuming you only want to change the bad one, how do you determine which one it is?

This of course assumes you even get warning signals. I’ve had batteries in other vehicles work great for several years, drive it to the store one day, come out of the store fifteen minutes later and *click…click…click*. No warning.

I do carry a jumper pack.

 

[Mr._Bill]

I’m brand spankin’ new to the whole Jeep auxiliary battery thing, so bear with me.

When you start getting warning signals of a weak battery, assuming you only want to change the bad one, how do you determine which one it is?

This of course assumes you even get warning signals. I’ve had batteries in other vehicles work great for several years, drive it to the store one day, come out of the store fifteen minutes later and the battery is *click…click…click*. No warning.

I do carry a jumper pack.

Removing the Aux Battery negative cable from the Main Battery negative post separates the batteries so that they can be independently checked or charged. When fully charged, with no load, they should each read 12.8 volts. The two batteries are paralleled together all the time, except during the Aux startup test and during ESS events. The primary purpose of the Aux Battery is to keep the computers stable during ESS events.

The only real warning signs are the messages that pop up saying ESS Unavailable or Aux Switches Unavailable. Remote Start will also stop working if the voltage levels drop below a certain point. There is an error light that will show, along with a message, if the Aux Battery fails the startup test. The only startup test for the Main Battery is whether or not the truck will start.

The life expectancy of the batteries in the JT is about three years. Warmer climates usually decrease the life span. They will last longer if they are kept charged, and fail sooner if they are not. The parasitic draw is fairly high, especially with a cellular equipped head unit. If the trucks are not driven enough to keep the batteries charged, they should have a battery maintainer connected when parked.

 

[ScooterInTX]

I travel a lot with work so mine can go easily a week without running.
Care to share more about this impressive setup?

Oh, boy. Learning from youtube video.

The batteries were extremely low. That was the problem. No need to search youtube and get into that "the aux battery causes poor mpg, climate change and death wobble" types of stuff.
But it's the "in thing, cool Jeep thing" to do. Why? Because it's repeated so many times.
If any of my cars sit for a month - they go on a tender (BatteryMinder)
My original batteries lasted fine in my first Gladiator, and the batteries in my current JT are over 2 years old and doing just fine.

This is how I charge mine when it sits for a few days (and it's been sitting a lot since I'm not really supposed to be driving with new meds and med conditions)

 

[Jteakus]

Looks like he is using the trailer plug to feed 12v to the 12v accessory and ground to the ground. Fused as well. No need to pop the hood. C7 Corvette uses similar setup using a 12v power port in rear hatch area. Nifty.

 

[gonemad]

Removing the Aux Battery negative cable from the Main Battery negative post separates the batteries so that they can be independently checked or charged. When fully charged, with no load, they should each read 12.8 volts. The two batteries are paralleled together all the time, except during the Aux startup test and during ESS events. The primary purpose of the Aux Battery is to keep the computers stable during ESS events.

The only real warning signs are the messages that pop up saying ESS Unavailable or Aux Switches Unavailable. Remote Start will also stop working if the voltage levels drop below a certain point. There is an error light that will show, along with a message, if the Aux Battery fails the startup test. The only startup test for the Main Battery is whether or not the truck will start.

The life expectancy of the batteries in the JT is about three years. Warmer climates usually decrease the life span. They will last longer if they are kept charged, and fail sooner if they are not. The parasitic draw is fairly high, especially with a cellular equipped head unit. If the trucks are not driven enough to keep the batteries charged, they should have a battery maintainer connected when parked.

This is most helpful. Thank you.

 

[Mr._Bill]

Looks like he is using the trailer plug to feed 12v to the 12v accessory and ground to the ground. Fused as well. No need to pop the hood. C7 Corvette uses similar setup using a 12v power port in rear hatch area. Nifty.

Adapters like these make it easy to do.

POLLAK 11-896 7-Way Power Outlet Adapter https://a.co/d/0nRgl1J

Tow Ready 118019 7-Way Cigarette Lighter Plug Adapter , black https://a.co/d/cbGg6gH

 

[gonzoy5]

I know, totally my fault when I left
it's still on the original batteries, should I replace the aux first?

Change them both. Pick something other than OEM and you'll be set. I did that a few months ago and realized it handled other gremlins I didn’t realize were associated to a weak aux battery.

 

[Zachanadandy]

The aux battery location is the problem, coupled with the fact it's completely unnecessary. Sure you could replace them both, but running 2 dissimilar sized batteries in quasi-parallel is the reason that 1 failing usually kills the other. They don't charge or discharge at the same rate. It's not enough of a complication that I'm going out of my way to remove the functioning aux battery, but I surely will never replace it. When it dies it gets deleted for simplicity sake.

 

[Lost1wing]

I’m brand spankin’ new to the whole Jeep auxiliary battery thing, so bear with me.

When you start getting warning signals of a weak battery, assuming you only want to change the bad one, how do you determine which one it is?

This of course assumes you even get warning signals. I’ve had batteries in other vehicles work great for several years, drive it to the store one day, come out of the store fifteen minutes later and *click…click…click*. No warning.

I do carry a jumper pack.

The first thing you may see is a battery charging message for an extended time. If you go for an hour or so drive and still see battery charging, it is time to recharge both batteries, test them and reset the IBS. If it continues showing battery charging, you may see start stop unavailable or other features may become unavailable.

If you eliminate the aux and see any of the above, that means your main is depleted to a point where it can leave you stranded.

If you still have the aux and ignore start stop unavailable or battery charging for long, you risk being stranded. Same goes for those with the aux but never look at the ESS page. Waiting for a symbol to show up is no bueno. I'd much rather see that my ESS has stop functioning and take precautions than attempt to start, only to find out that the battery is to weak to start the engine.

2020 original batteries and my ESS is functioning like normal. I due put a tender on it, if it sits very long.

 

[Erievon]

Before you go replacing all the batteries, get a good solid charge on the main and see how it does (leave the aux bypassed) If the main fails to hold a good charge, replace the main and forget the aux. You've already got the aux bypassed, why bother putting it back online.

 

[DailyMoparGuy]

Before you go replacing all the batteries, get a good solid charge on the main and see how it does (leave the aux bypassed) If the main fails to hold a good charge, replace the main and forget the aux. You've already got the aux bypassed, why bother putting it back online.

Doing this now. Main battery is cooked and will be properly disposed of. My aux was at 3.81V when I took it off the truck. Been charging it for a couple hours and it’s currently at 13.3V, just 0.1V from the recommended 13.4-13.9V range

Since the aux is good, I’ll store it in case I have problems with the delete. Not going back on my truck otherwise. Got an Optima Yellow AGM main battery to pick up from AutoZone today. Done with the dealer service depts forever. Can’t stand em.

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