Top Reasons for ESS failure

[RussJeep1]

Started my JLU Sahara this morning. About 5 seconds later it tells me that the Auto Start Stop isn't working. (I know, some of you would consider that a blessing. I'm just concerned that the light coming on isn't reflective of more serious issues.)

What are some of the top reasons this could be? FWIW, we got bad thunderstorms last night. Maybe something has shorted. My dealer won't see me until the 28th!

I saw some videos on how to disable ESS and confirmed that neither hood up switch #2 or the intelligent battery terminal connections were loose.

I'm hoping it's something that dries out.

Thanks.

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[Sunin-Retired]

If your engine is cold

 

[Jebiruph]

Was it just a warning light? What did the Stop/Start information display say?

 

[Jebiruph]

I would keep an eye on your battery voltage until the issue is resolved.

 

[RussJeep1]

I would keep an eye on your battery voltage until the issue is resolved.

The display showed the letter "A" with a circle around it for autostart, and a slash through it for "it doesn't work," and the rig dinged once.

It went away latter in the day. I think it might be, or at least I hope, last night's thunderstorm and some crazy sideways rain creating a temporary short.

Thanks for the replies. I will watch the things suggested, and I did check battery voltage, which was excellent.

I think a cold engine won't let it engage, not suggest there's a problem with the system and that it will never, under any circumstance, engage, but who knows what the JL's computer is thinking here.

I so wish we had access to the algorithms and decision logic.

 

[Martindfletcher]

Mine goes into battery protection mode than ess doesn’t work. Normally on a long road trip,

 

[Jebiruph]

The display showed the letter "A" with a circle around it for autostart, and a slash through it for "it doesn't work," and the rig dinged once.

The Stop/Start information display on my sport will display messages like Stop/Start not enabled because seat belt not buckled, engine not up to temp and things like that. You have to cycle the information display to that screen.

 

[turk]

in addition to the battery voltage issue which seems to be the cause for a large segment of owners experiencing this issue the 2nd most common issue is a faulty door wiring latch usually present on driver side front in the jlu

to test if you have this problem. disconnect the door wiring harness connectors as you would if you were going to take the doors off. start the engine. if the warning goes away and ess functions normally you have one of the faulty harnesses. your dealership can also confirm this error code to the door wiring harness latch.

 

[Biscuit]

Started my JLU Sahara this morning. About 5 seconds later it tells me that the Auto Start Stop isn't working.

D'oh! ESS isn't functional until the engine reaches normal operating temperature.

 

[RussJeep1]

D'oh! ESS isn't functional until the engine reaches normal operating temperature.

Biscuit: you're rude and you misread. I didn't ask why, at my, say, first traffic light 30 seconds from my home the ESS didn't engage. I'm well aware of many of the factors that would have the ESS not kick in, from engine temperature, to battery voltage, to operational of the air conditioning on high, etc. In fact I discuss this in my post immediately above and explain the problem in my first post adequately enough for others to understand. This is the OPPOSITE of a broken ESS I describe. It's a vey much working ESS that's detected conditions not suited to its engaging at a vehicle stop.

Maybe I didn't make myself clear. Another poster had your suggestion but he didn't put the stupidity on me.

I'm asking why the vehicle turned the ESS error light on, on the dashboard, 5 seconds after turning over the rig.

There is a difference between a working ESS system, that doesn't engage because, say, the engine is cold, and which doesn't display an ESS failure light on the dash because the ESS IS working--in fact it's working enough to know it shouldn't engage yet--and a broken ESS system that displays a diagnostic on the dash.

The problem ended up going away. Maybe it was low ESS battery voltage that charged with enough road mileage. The rig's diagnostic screens showed 14.4V, but that could have been on the main battery only. I don't know which voltage(s) are shown on the dash.

 

[Sierra Nevada]

I've noticed how hard the brake is pressed will/will not trigger ess. It seems how high the battery's voltage is will start the engine, but no data to support.

 

[Shots]

Well, Biscuit isn't wrong that it cold be the engine not up to temp. If the engine is cold upon startup, it could display the ESS disabled message, along with the "A" warning lamp.
Many factors go into ESS on/off. If any of the various conditions aren't met upon start up you can get the warning message and lamp. That includes low engine temp.

 

[Jebiruph]

Well, Biscuit isn't wrong that it cold be the engine not up to temp. If the engine is cold upon startup, it could display the ESS disabled message, along with the "A" warning lamp.
Many factors go into ESS on/off. If any of the various conditions aren't met upon start up you can get the warning message and lamp. That includes low engine temp.

I've never seen the "A" warning lamp when Stop/Start is not enabled due to low engine temperature. "A" means something is broke, not enabled means the conditions aren't right for Stop/Start to engage.

 

[RussJeep1]

Well, Biscuit isn't wrong that it cold be the engine not up to temp. If the engine is cold upon startup, it could display the ESS disabled message, along with the "A" warning lamp.
Many factors go into ESS on/off. If any of the various conditions aren't met upon start up you can get the warning message and lamp. That includes low engine temp.

No: he's quintessentially wrong. You too/two are missing the point. That a working ESS might not engage because of a cold engine was never asked, never questioned, never not known by this OP and not something that turns on (or is suppose to turn on) its warning light. In fact that would be the sign of a working ESS that it wouldn't engage, but also NOT light up a diagnostic light in the display panel.

The light on the panel says that the ESS won't engage because it is incapable of discerning whether conditions hold for it to engage, or something other than a cold engine prevents it from doing so, like maybe low voltge.

"If the engine is cold upon startup, it could display the ESS disabled message, along with the "A" warning lamp."

Not if it's working correctly should it. The warning lamp means the ESS is broken and has nothing to do with whether at any moment a working ESS will or won't engage because of something like a cold engine condition.

So when I turn the air conditioning on high the ESS warning light goes on ? Of course not. Because an ESS that doesn't engage when engine load from a high fan and compressor demand justify it not engaging, IS a working ESS.

I'm well aware of the documented reasons a working ESS might not engage. Again, to beat a dead horse: It's precisely because it's working that it DOESN'T engage.

I discuss a broken ESS. See the title? ESS failure; not ESS failure to engage.

 

[RussJeep1]

I've never seen the "A" warning lamp when Stop/Start is not enabled due to low engine temperature. "A" means something is broke, not enabled means the conditions aren't right for Stop/Start to engage.

Thank you! Thank you for getting "it."

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