2021 Wrangler - ESS Not Ready Unless AC / Heater is Completely OFF

[Hutchy68]

I know there are multiple threads about how bad ESS is on Jeeps. My son purchased a new 2021 Wrangler Willys. I am completely shocked by how bad the ESS system is on this Jeep. We took it to the dealer after 700 miles of no ESS because the ESS AC / Heating Warning constantly shows - Not Ready. While he was driving, I fiddled with the AC, and even though it wasn't on, ESS not ready continued to show. He was running the blower fan, and I shut it off completely. Suddenly, the ESS System showed Ready, and it worked at the next light. It is smooth and quiet. I turned the fan up 1 click to the low setting, the engine started, and Not Ready showed again.

Dealer stated this was the way it is intended to work. Getting this straight in my mind, if you use the AC or the Heater, ESS will never work in the Willys. That has got to be about the DUMBEST thing I have ever heard. I get MAX AC and other specific causes, but from the printout of the Service library they gave us, the "HVAC demand is not present" is why the ESS will not show ready and this is normal.

Can someone explain this a bit further? Because as of right now, the ESS will work 4 days in April and 5 days in October as long as he is not running the blower fan for the HVAC system. We do have the whole list of conditions for the ESS auto stop event to take place. I can post an image of it.

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[aldo98229]

Welcome to the forum!

That dealer is full of shit.

These issues are well documented.

Try these:

1. Check that the fuses are all properly seated
2. Make sure the battery terminals are properly tightened
3. Check that both batteries are charging

None of this is rocket science, but for some reason it appears to be for Jeep dealers.

80% probability you will solve the ESS issue with one of those three steps. If not, then it is time to escalate things.

Good luck!

 

[RandomSquirrel]

I think there is something wrong with yours, as even with the AC on (auto set to 68 degrees), and when it's barely blowing, the ESS will kick-in, shut off the engine, air still blowing from vents, and ESS will startup either a) if more cooling is needed or b) I take my foot off the brake.

 

[Erievon]

Is this at all times? Even if the ac is off, if just the blower is going and you have auto climate, if the temp in the cabin is not down to (or up to in the case of heat) the ESS will not activate until that condition is satisfied. Could be a bad interior temp sensor if it happens after driving long enough and it's at the selected temp in the cab.

 

[Hutchy68]

Welcome to the forum!

That dealer is full of shit.

These issues are well documented.

Try these:

1. Check that the fuses are all properly seated
2. Make sure the battery terminals are properly tightened
3. Check that both batteries are charging

None of this is rocket science, but for some reason it appears to be for Jeep dealers.

80% probability you will solve the ESS issue with one of those three steps. If not, then it is time to escalate things.

Good luck!

Thanks and this is what I thought. It makes no sense. Why sell a vehicle with ESS if it won't work using the AC or Heat.

I will check those recommendations, but how do I escalate the issue? We did do a customer care call and escalated it to a specialist. Mainly for the drop at the dealership this morning with an appointment. Then telling him at 7:30 am they couldn't look at the Jeep until Friday with them stating they told us this. Bullshit. That was a ridiculous obvious lie. Why are we dropping a vehicle the day before a service?!?

Anyway, the whole printout they gave us appears to be related to the customer care call. I did just notice an "Ambient temperature is within calibrated range" in the list near the top. What does that mean? I would think it means ambient cabin temperature, but not sure.

What the service (keyboard puncher) tech couldn't tell us, is the list given is pertinent to this Jeep's VIN or not. The main issue is Jeep has done a TERRIBLE job with vague terms and conditions needed for the ESS to work. Their Mopar video is a joke. I was thinking about buying a Grand Cherokee, but now I am going to re-think it.

 

[Chupacabra]

If the cabin isn't sufficiently heated or cooled to your set temperature, the ESS will not engage.

In the morning I drive with the blower on (no A/C) because it's reasonably cool outside. The ESS does not kick on under these conditions because the cabin will never cool down enough but I like the air blowing in. If I turn the HVAC system completely off, it will engage the next time I come to a stop.

ESS will kick on in mine with AC on, but it has to have been running a while and the cabin cooled to the set temperature or it won't engage. Even if ESS kicks in, if it's hot out and the light is long, it will restart the engine before the light turns green.

What you're describing is pretty much what I see with mine regarding the HVAC controls and ESS.

 

[Jeepaddict76]

On my 18 JLUR, V6, 6 speed, the ESS would shut engine off every time Jeep would come to a stop unless AC was on Max. The system was so intrusive that I disabled ESS.
On my 21 JLUR, 4 cyl turbo, ESS doesn't turn engine off if AC is on any manual setting. Living in FL my AC is almost always on so ESS doesn't bother me one bit on my 21.
Sometimes I wonder if Jeep intentionally adjusted ESS on the 21's or if I just got lucky?

 

[Ridgway Jeeper]

I think it is interesting somebody is upset that their Jeep isn't shutting off and restarting all the time... That's a new one for me. I WISH ours never tried to stop start, that would be awesome. The way it is we occasionally get caught not disabling it and it shuts off. I do not need nor want this stupid feature personally.

 

[Hutchy68]

The only thing that upsets me is a selling point that is obviously flawed with vague documentation. If you pay for something, you should get what you pay for and at least the dealership and their mechanics should know about the feature. Cars I've driven with ESS just work. It takes getting used to but when implemented right, it's doing your part (a little at least) without jumping on the all-electric bandwagon.

@Chupacabra - thanks for the information. We will try that too.

 

[mgroeger]

Wow this is the first thread I've heard of someone complaining the ESS wasn't working. Heck, tons of us have dropped $200 or more on Tazers to disable that POS system from ever working. I HATE it and think of all teh abuse it is putting on your starter especially in stop and go traffic.

 

[Gee-pah]

As if he didn't explicitly say it, (and he did) the OP @Hutchy68 68 takes issue with being sold a bill of goods by Jeep on ESS that didn't delivery in actuality.

Tom: some background, some standards, and some ways to redress the situation.

The way Jeep designed ESS (which BTW is flawed, more below) should--when the batteries are fully charged and working--allow ESS to still work on lower climate control settings.

When designing their ESS system, itself motivated by avoiding the enormous costs the EPA would have charged Stellantis if their fleet had not met certain MPG standards that ESS systems help address--care of the EPA rules on determining MPG, the Wrangler engineers realized that it was probably unwise, like other ESS vehicle implementations, to do their Wrangler ESS with one battery. Wrangler owners just have too many appliances for such a design that would rob the battery of cranking power at an ESS stop, where too many electric drawing items (i.e. appliances) were running concurrently.

The best design would have been one with two equally sized batteries, ideally where the batteries rotate being the main and supplemental ones every X number of engine cranks. Any battery scientist will tell you that the difference in size of the batteries inherently flaws the system. Could Stellantis have made standard a bigger alternator so even short trip drivers could have topped off bigger standard equipment batteries--sure: at both purchase price and MPG cost.

But I'll bet the "suits" said "make it work at this cost," and that cost necessitated use of the motorcycle size ESS battery.

The way to address this with the dealer is to ask the dealer to independently, on each battery, apply a load tester and document for you the results. This test, in case you're unfamiliar, is not simply to check voltage, but to attach each battery independently to a device (a load tester) that will measure each battery's ability to deliver and accept electrical current independently.

And only because dealers can be enormously stupid, this does not involve simply putting the load tester on the leads of the main battery. Such a test would be a composite test of both batteries together, as (at least the 3.6L) has both batteries in parallel 99.99% of the time in this vehicle but for an instant at cold cranks and during ESS events.

Rather, the dealer needs to first, temporarily remove the cables from the main battery's negative post. Then, placing the load tester on the main battery's posts will load test the main battery.

After this, the negative lead from the load tester should be moved to the dangling wires. This will test the ESS battery: yes, even though the positive lead on the load tester remains in the main battery's positive post.

Make sure to have those dangling cables reconnected.

I'd like to know what the load tester found.

~~~~~~~~

Now--all this said, I still, like many owners, hook a trickle charger in my driveway up to shore power at one end (110V A/C) and the main batteries
posts at the other end. This charges both batteries given the parallel connection of the batteries when the vehicle is at rest. This keeps my batteries topped off and allows ESS to engage the maximum amount of time.

Now: am I fooling myself that to save one form of energy (gasoline) I am using another form of energy (electric) to trickle charge my batteries so ESS has the best change of engaging?

...why yes....yes I am.

 

[mgroeger]

Rather, the dealer needs to first, temporarily remove the cables from the main battery's negative post. Then, placing the load tester on the main battery's posts will load test the main battery.

After this, the negative lead from the load tester should be moved to the dangling wires. This will test the ESS battery: yes, even though the positive lead on the load tester remains in the main battery's positive post.

Incorrect. The only way to correctly load test the battery is to have it completely disconnected from everything... i.e. BOTH positive and negative terminals. Keeping the positive terminal connected links the two batteries. My dealer did this same thing and it showed my battery being good when it wasn't.
Once the batteries were completely isolated it showed them to be bad.

 

[Gee-pah]

Incorrect. The only way to correctly load test the battery is to have it completely disconnected from everything... i.e. BOTH positive and negative terminals. Keeping the positive terminal connected links the two batteries. My dealer did this same thing and it showed my battery being good when it wasn't.
Once the batteries were completely isolated it showed them to be bad.

Keeping the positive terminals connected (and only the positive terminals) links the two batteries? Ok, but news to me.

For a battery to be attached to something, my understanding was that a circuit had to form.

My instructions of removing all cables from the negative post of the main battery isolated that battery and the ESS battery from all appliances and the body grounds, and each other.

I suppose disconnecting all the cables from the positive post of the main battery could not hurt, I just wasn't aware that it would make a difference.

 

[mgroeger]

Keeping the positive terminals connected (and only the positive terminals) links the two batteries? Ok, but news to me.

For a battery to be attached to something, my understanding was that a circuit had to form.

My instructions of removing all cables from the negative post of the main battery isolated that battery and the ESS battery from all appliances and the body grounds, and each other.

I suppose disconnecting all the cables from the positive post of the main battery could not hurt, I just wasn't aware that it would make a difference.

https://www.jlwranglerforums.com/forum/threads/3-6l-ess-battery-diagram.14401/

 

[Gee-pah]

https://www.jlwranglerforums.com/forum/threads/3-6l-ess-battery-diagram.14401/

I'm confused Mike. You've provided a link to what I presume is the wiring diagram in the first post of a thread, with no accompanying explanation, that basically makes what I thought was my case.

And that case is that removing all wires from the negative post of the main battery isolates that battery from all appliances, the body ground and the ESS battery, as well as the ESS battery from all appliances, the body ground, and the main battery--essentially putting each battery on its own metaphorical private island where no appliances exist.

I'm not taking issue that your load testing differed with positive wires only connected between batteries so much as I wonder why.

Maybe you'd prefer the ESS negative to be separated from the "current sensor" i.e. IBS.

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