Jeep Died - While Driving

[whiterubicon]

OK - so a day ago I noticed that the Jeep told me that the start/stop function was disabled because the battery was in protection mode. I was on the way to AutoZone and when I came to a red light, the Jeep shut off, like the normal ESS - but it did not start up again. I tried a few times and then called roadside assistance. They towed me home (I was only about 2 miles away) and I tried to jump the Jeep. I tried by using just the battery terminals and then trying first post in the fuse box - nothing worked. I used a multimeter, and the main battery test good - 12.51. That is with the auxiliary battery that is still hooked up. The main battery is the one that came in the Jeep from 2019 - and the auxiliary battery is about 1 year old. Do I need to remove them both and test them separately? I would prefer to test them myself and not have AutoZone do it. Made for a very frustrating evening.

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[STW]

I'm new at doing ESS/Aux bypass, but I think you should disconnect the aux battery--see the Jumperless battery bypass thread. It means removing the aux neg cable from the neg terminal (the aux neg cable is the skinnier one), and pulling fuse F42. You'll see the process in the thread.

Once the batteries are separated, you can (try to) charge and test them separately. I went through this on the weekend if you see my Noco post below. Mine didn't fail to start but both batteries failed to charge--fully discharged. I used a de-sulfating Repair function and got them charged eventually but am leaving the Aux disconnected.

You may have done all this already since you posted this Monday, but just in case.