There's an ESS information display that will tell you the reason ESS is not functioning. Its usually Battery Protection mode when mine isn't activating.ESS Issue: I seem to be having the opposite ESS issue (or should I say ASS???). I got my 2018 JLU Sahara in October 2018, and the ESS was working fine, but now it seems to not work. I came to a stop (gas tank was full), and no engine shut off. Most people would think this may not be a problem, but I got to thinking, could this be a start of a new problem with the electrical system of the jeep?
Mine said charging all the time as well and after the dealer checked it they found the main battery bad, also do you have a programmer installedI'm not sure when mine stopped working but it's always saying that it's charging, even with 40+ minutes of driving. I guess that's a "feature" and not a bug as I used to always disable it every time I start the Jeep.
To add on to @Rhinebeck01 reply, There is another condition where the outside temperature is too cold and ESS will not function as well. I've only seen "Battery Protection Mode" in below freezing temperatures so I think that's what it displays when the outside temp is too low for ESS.My ESS display said "Engine too cold" Does the ESS not function when its cold??