ESS not working

[trailless]

My JT has about 270 miles now. However, ESS has never worked from day 1. I tried it with the AC off and on, it just always says that it's not ready. I'm not complaining as I would just turn it off anyway. Just curious as to why it doesn't work.

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[Mr._Bill]

This is usually an indicator that the ESS battery needs replaced. Have the dealer test both batteries.

 

[JAVIERGONZO]

Some would say you're pretty lucky. ?

 

[jeepers29]

This happened to a friend in their JL. The ESS battery was shot and ended up draining the main battery as well. As mentioned, have both batteries tested.

 

[trailless]

Well at 327 miles, ESS started working... Im definitely turning it off when I install my Tazer Mini.

 

[Hootbro]

Mine took a few hundred miles before it started working also. 2- 1/2 years later, still on the factory batteries for both of them with no issue.

If I had to guess, I would speculate the smart battery monitoring/charging system takes awhile for both batteries to level out on state of charge before it allows the ESS to start working properly

 

[Sportsbiz]

Mine stopped working this past week as well, and received the display shown below. I have an appointment with my local dealer next week. From other posts I’ve read here its likely the aux battery.

 

[Dan in Pasadena]

Resurrecting this old thread because my 2020 JTR with about 34,000 miles threw the same code as in pot #7 above a week ago. Nothing else has happened. Nothing seems wrong with the main battery. Is it just a matter of time?

The Start/Stop worked fine when I bought my truck; used from Caravan with about 15,000 miles in July, 2021. It's a feature that never bothered me. Stopped working a month or two ago, that also didn't bother me but I suspected something was up. The dash said something like it wasn't ready or battery was charging - sorry, I can't remember now.

Then the "@" thing showed up. Made an appointment to take it to dealer next week. Service writer said likely the AGM battery or "could be a battery sensor". WHAT battery sensor? This is gonna cost a bunch to fix, right?

 

[Mr._Bill]

Resurrecting this old thread because my 2020 JTR with about 34,000 miles threw the same code as in pot #7 above a week ago. Nothing else has happened. Nothing seems wrong with the main battery. Is it just a matter of time?

The Start/Stop worked fine when I bought my truck; used from Caravan with about 15,000 miles in July, 2021. It's a feature that never bothered me. Stopped working a month or two ago, that also didn't bother me but I suspected something was up. The dash said something like it wasn't ready or battery was charging - sorry, I can't remember now.

Then the "@" thing showed up. Made an appointment to take it to dealer next week. Service writer said likely the AGM battery or "could be a battery sensor". WHAT battery sensor? This is gonna cost a bunch to fix, right?

The battery sensor is connected to the negative post of the main battery. The cables connect to the sensor. It should be okay.

The life expectancy of the AGM batteries in the JT is about three years. Usually, the quickest fix is to just replace both batteries. Make sure the new batteries are both fully charged before installing them. Be careful not to short the cables or allow the ends to touch metal while changing the batteries.

 

[NotSo Bright White]

Mine hasn’t worked since new as I only drive it to the beach once a week. Took it to the dealer two times and they checked the batteries and said they are fine. I put a Naco battery tender on it and now it always works until I shut it off, which is done quickly. Plus it is sitting in my driveway plugged in and no one will steal it because they think it is a plug In hybrid. :{)

 

[Dan in Pasadena]

The battery sensor is connected to the negative post of the main battery. The cables connect to the sensor. It should be okay.

The life expectancy of the AGM batteries in the JT is about three years. Usually, the quickest fix is to just replace both batteries. Make sure the new batteries are both fully charged before installing them. Be careful not to short the cables or allow the ends to touch metal while changing the batteries.

Why the need to replace BOTH batteries when it starts fine using the main battery? Is the AGM battery putting a drain on the main that will eventually kill it and I just don't know it yet?

I ask because we are leaving on a trip through the Southwest - Taos, Canyon de Chelly, Santa Fe, etc. towing it behind our RV. Will be gone a few weeks. I decided to let dealer fix it because of this. With my luck the truck would crap on me in the middle of BFE and no cell service!

 

[Mr._Bill]

Why the need to replace BOTH batteries when it starts fine using the main battery? Is the AGM battery putting a drain on the main that will eventually kill it and I just don't know it yet?

I ask because we are leaving on a trip through the Southwest - Taos, Canyon de Chelly, Santa Fe, etc. towing it behind our RV. Will be gone a few weeks. I decided to let dealer fix it because of this. With my luck the truck would crap on me in the middle of BFE and no cell service!

Both of the batteries are AGM. They are paralleled together all the time, except during the startup test and during ESS events. When the batteries are replaced due to age, they should both be replaced. If one is replaced early, due to a defect, it is okay to not replace the other. An Aux battery that is older may put some drain on the primary battery, but usually not enough to be a problem until it fails.

I replaced my primary battery last fall when it died. I bought a new Aux Battery, but have not had time to install it yet. The original is now four years old, but still functioning. The batteries stay charged, due to being driven regularly, and ESS is usually off, so I don't have to worry too much about relying on it when ESS shuts off the engine.

When they come from a good batch, the Aux battery should have a longer life than the primary, since it is further away from the engine compartment heat.

 

[ShadowsPapa]

Why the need to replace BOTH batteries when it starts fine using the main battery? Is the AGM battery putting a drain on the main that will eventually kill it and I just don't know it yet?

I ask because we are leaving on a trip through the Southwest - Taos, Canyon de Chelly, Santa Fe, etc. towing it behind our RV. Will be gone a few weeks. I decided to let dealer fix it because of this. With my luck the truck would crap on me in the middle of BFE and no cell service!

"Starting fine" is only a fraction of the health of a battery. It can crank and start - but have diminished capacity. It may die in time of non-use, for example.

It's almost never the battery sensor. Don't let them fool with it. MOPAR has a STAR bulletin out warning dealerships to not replace that IBS unless there are certain codes because stupid techs who don't know how to check things correctly were saying "it may be the IBS so we'll replace it".
RESET it, yes, but replace? Rare for sure.
Frankly, I'd not want that tech to mess with it.

 

[Beemer533]

My second time into the dealer for batteries they also replaced the IBS. I think they said it weren't able to tighten the terminal properly..

 

[Dan in Pasadena]

Hmmm, A STAR bulletin - Do you know why it says not to replace them or what codes have to be showing? Any way to know the number of that bulletin?

Because the service writer mentioned it when we made the service date! Probably an easy way to boost the service price.

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