Start/Stop temperature 'limits?'

[Maverickxeo]

I tried to find it in the manual, but I don't see anything about the gas engine and start/stop not working below a certain air temperature - but I've noticed when it's colder out, it just says 'start/stop not ready.'

Basically, is there a 'typo' in the manual and where it says that the diesel engine start/stop has a minimum air temperature to run; it means the gas engine as well?

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[AFD]

Not 100% sure, but if my heater is going full blast still trying to get interior temps up to desired temp (or on 'hi' temp) the dash will usually state something about ESS 'not ready' and something about 'heating/AC' (or just 'not ready' with no reason).

Think that's at least part of it, but not really sure how much exterior temps play a factor if, for example if the heater was set low or off. But you're right, it really doesn't seem like it wants to work during sub-32F temps.

 

[Beachcomber72]

I tried to find it in the manual, but I don't see anything about the gas engine and start/stop not working below a certain air temperature - but I've noticed when it's colder out, it just says 'start/stop not ready.'

Basically, is there a 'typo' in the manual and where it says that the diesel engine start/stop has a minimum air temperature to run; it means the gas engine as well?

start-stop system won’t activate if your heating or cooling the interior temperature until you reach the temperature you set your a/c and heater control to.

Basically the system knows not to shut off at a stoplight if you told it to cool you down because that wouldn’t be very cooling/heating efficient if it did.

 

[Maverickxeo]

start-stop system won’t activate if your heating or cooling the interior temperature until you reach the temperature you set your a/c and heater control to.

Basically the system knows not to shut off at a stoplight if you told it to cool you down because that wouldn’t be very cooling/heating efficient if it did.

I've seen the 'heating/cooling' alert on the start/stop screen, but this also occurs without the heat/AC on - the only thing I can think of is that air temperature is too low. Once it gets above 0C; it starts to work (unless it's coincidental).

 

[Reinen]

There isn't a min/max limit for ESS per se. What limits it temperature wise is if you have Heat/AC on. ESS won't sacrifice cabin heating & cooling to stop/start.

 

[Paluss]

There isn't a min/max limit for ESS per se. What limits it temperature wise is if you have Heat/AC on. ESS won't sacrifice cabin heating & cooling to stop/start.

Not really, we had a colder then normal day here in Maryland, first drive in the morning at 31 degrees (using off road pages) at the first light I stopped at the engine Oil and coolant was around 131 degrees (temp set to 72) and the ESS kicked in a stopped the engine. I just eased my foot of the brake pedal to restart the engine as the cabin was still a bit cold. 22 JLURD, but I noticed when I had my 2018 v6 after a few years in cold weather it would take a very long time for ESS to kick in, and some times it didn't on a 19 mile commute (I would get several messages including battery charging) . I think as the batteries age it takes longer and longer for them to charge enough to activate ESS.

 

[Reinen]

Not really, we had a colder then normal day here in Maryland, first drive in the morning at 31 degrees (using off road pages) at the first light I stopped at the engine Oil and coolant was around 131 degrees (temp set to 72) and the ESS kicked in a stopped the engine. I just eased my foot of the brake pedal to restart the engine as the cabin was still a bit cold. 22 JLURD, but I noticed when I had my 2018 v6 after a few years in cold weather it would take a very long time for ESS to kick in, and some times it didn't on a 19 mile commute (I would get several messages including battery charging) . I think as the batteries age it takes longer and longer for them to charge enough to activate ESS.

The JL can maintain a 72 degree air temp with coolant at 131 and it was likely doing that. But all it can monitor is air temp, not the temp of everything else. If everything else is still cold it will drop the air temp quickly. If you didn't preemptively initiate the restart by the brake, the engine would likely have soon restarted on its own because the HVAC needed it to maintain 72 degree air.

The 2018 was a more serious situation and would have shown a different message on the ESS screen. If "battery charging" is ever shown on the ESS screen during normal everyday use, that's an early warning sign of failing batteries. It's just a matter of months before strange electrical gremlins start appearing and the JL ultimately refuses to function due to bad batteries. That can happen both when trying to cold start the engine or even while you're driving with the dreaded "STOP SAFELY THE VEHICLE WILL SHUT OFF SOON" message.

 

[MesaAZGuy]

I haven't noticed my new XR doing its start/stop thing. No heat or air running. Is there a setting on the Uconnect to get it going? I guess I should read the manual but I would have to open the shrink wrap!

 

[Tethmes]

I guess I should read the manual but I would have to open the shrink wrap!

You can access your manual through the My Jeep app on your phone if you don't want to open the paper one. Not that it matters much outside of a personal tick, your resale value isn't impacted by the manual being unwrapped or not lol.

To OP:

There's no outside temp that is a limiting factor. What is a factor is the vehicle's normal operating temperature. It won't enable ESS if your engine is still warming up, and as others mentioned, if the climate control is on full blast.

 

[Paluss]

The JL can maintain a 72 degree air temp with coolant at 131 and it was likely doing that. But all it can monitor is air temp, not the temp of everything else. If everything else is still cold it will drop the air temp quickly. If you didn't preemptively initiate the restart by the brake, the engine would likely have soon restarted on its own because the HVAC needed it to maintain 72 degree air.

The 2018 was a more serious situation and would have shown a different message on the ESS screen. If "battery charging" is ever shown on the ESS screen during normal everyday use, that's an early warning sign of failing batteries. It's just a matter of months before strange electrical gremlins start appearing and the JL ultimately refuses to function due to bad batteries. That can happen both when trying to cold start the engine or even while you're driving with the dreaded "STOP SAFELY THE VEHICLE WILL SHUT OFF SOON" message.

You are correct on the 2018 the aux battery was slowly going bad, I drove it from Maryland to NYC and back the same day and ESS never engaged, I recall at least 6-8 different messages of why ESS was not available (vehicle not on level ground, seat belt not fastened, HVAC heating or cooling, battery charging their must be over 20 different messages it became funny.) then I went to the dealer I was told that the Aux was less then 30% charged (but that the battery has to fail charging for a replacement) but with that being my second visit my SA said I will make sure it will fail wink wink , and it was replaced under warranty just shy of 3 years. I just went to the airport to pickup my daughter, at my first stop Oil and coolant 48 degrees (temp in garage) 38 degree temperature outside and ESS engaged at the first stop again, Usually at around 100 degrees (coolant) is when I notice warm air blowing in the cabin. I'm not complaining, I am one of the few that doesn't mind having ESS....

 

[Reinen]

I recall at least 6-8 different messages of why ESS was not available (vehicle not on level ground, seat belt not fastened, HVAC heating or cooling, battery charging their must be over 20 different messages it became funny.)

Yup, that would be the electrical gremlins I was talking about. The JL is very electronic so when the battery can't maintain adequate voltage all the time weird stuff happens. It's like the JL starts developing Alzheimer's disease. It slowly and steadily starts having no clue what's going on and comes to progressively bizarre conclusions until it's finally completely dysfunctional.

then I went to the dealer I was told that the Aux was less then 30% charged (but that the battery has to fail charging for a replacement) but with that being my second visit my SA said I will make sure it will fail wink wink , and it was replaced under warranty just shy of 3 years.

This is why dealers drive me nuts. That bad Aux was damaging the Main. Just replace both of them already, we all know what's going to inevitably happen.

I just went to the airport to pickup my daughter, at my first stop Oil and coolant 48 degrees (temp in garage) 38 degree temperature outside and ESS engaged at the first stop again, Usually at around 100 degrees (coolant) is when I notice warm air blowing in the cabin.

I'm impressed with the degree you monitor your JL. Nerd to nerd. ?

I'm not complaining, I am one of the few that doesn't mind having ESS....

I like it too, if only for the real-time passive monitoring of the electrical system. The electronics will stress AGM batteries whether it's single or dual so I like the early warning. And if it saves some gas, well, bonus.

 

[Maverickxeo]

You can access your manual through the My Jeep app on your phone if you don't want to open the paper one. Not that it matters much outside of a personal tick, your resale value isn't impacted by the manual being unwrapped or not lol.

To OP:

There's no outside temp that is a limiting factor. What is a factor is the vehicle's normal operating temperature. It won't enable ESS if your engine is still warming up, and as others mentioned, if the climate control is on full blast.

In the situation I've experienced, the engine was at operating temp, the heat/ac was not on, and the battery had sufficient voltage. The only thing I could rule was it was below 0C outside. On the same drive, once the air temp went up to 3C, it started working, and stopped again when it dropped again.

 

[Tethmes]

In the situation I've experienced, the engine was at operating temp, the heat/ac was not on, and the battery had sufficient voltage. The only thing I could rule was it was below 0C outside. On the same drive, once the air temp went up to 3C, it started working, and stopped again when it dropped again.

Not trying to discount your experience, just saying that it's not how the system works. There had to be some other factor at play. For example, my ESS was working just fine this morning at 19f which is around -7c. If it was a matter of ambient temperature, it would be programmed in across the board. I'd recommend getting your system diagnosed.

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