ESS Diagnostic help

[Soul Man]

UPDATE: FIXED see 5th post

Warning light for ESS on dash and "Start/Stop Unavailable Service Start/Stop System" message.
2020 Willys

Took out fuse and removed ground from Aux (closest to passenger fender) per Jumperless Aux Battery Bypass | Jeep Wrangler Forums (JL / JLU) - Rubicon, Sahara, Sport, 4xe, 392 - JLwranglerforums.com and no change (several start/stops/miles driven since then).

Took to Auto Parts store and load tested main battery (+/- on main) and it was good. (ALSO) getting 13.5-13.9v on dash when motor running.

Had them load test Aux (+ main and the - on the disconnected lead from the Aux) and he said the Aux was bad. (But if this was the real problem all should be good once I bypassed?????)

FULL STORY:
Shorted out power cable to winch (got loose and rubbed on belt). After this happened, I started it up fine and shut it down to make sure things still working after i removed the bad cable. Later that day started it fine, drove about a mile and got "Pull over, everything about to shut down" warning on dash and then everything shut down (which I now know is the Aux /PDC going bad...)

Took to dealer who said bad breaker in the PDC and they replaced the PDC and got it running.

Told me they tested battery(ies?) and was good :/

Prior to all this, alternator clutch was going bad/loud. They replaced alternator, but damaged the connector/harness and had to get a part to replace that.

Picked up Jeep after them having it for FOUR WEEKS and the ESS light was on (so they returned me a Jeep in need of service after having it for 4 weeks) and was so disgusted I took it home. Also, they charged me 5 hours labor to trouble shoot which makes me mad now that I know that is the exact symptom of the Aux/PDC not working

1.) I actually DO like the ESS and would like it to work (knowing if it strands me I can pull the fuse and disconnect ground and get running again (?))
2.) More importantly, if too expensive/trouble to fix I want to make sure nothing is going to strand me.

Any suggestions?
Have appt on Wed with another dealer, but if just replacing the Aux, I can pull fender and do that myself (already ordered the fasteners!)

Edited the load test first paragraph for clarity.

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[Steph1]

Was gonna get the battery replaced for a second time until online searches lead me to the solution of a permanently installed battery charger. Whenever it takes longer for the SS to work or I know that my Jeep wont be sufficiently used for numerous days, I just plug it and since then, everything works flawlessly.

 

[58Willys]

13.8 volts while motor running is not a load test; that’s a charging test. Sounds like you may have a few things going on. In order to diagnose electrical issues, you need to start with fully charged batteries.
Charge batteries, test for voltage which should be 12.6 - 12.8 v. Then load test batteries individually. If anything fails, replace both batteries, even if only one is bad. Then work through any rempaining issues.

 

[Soul Man]

Thanks. Voltage is the running voltage. I had them load tested at the auto parts store with a load tester, that's when they said the Aux failed.

58 Willys, they way I wrote that in the OP is misleading. 2 different data points: had load tested at Auto part store and separate piece of info is that my voltage is good.

 

[Soul Man]

UPDATE, FOUND PROBLEM AND WORKING

Rhinebeck01 was cool enough to talk me through it on phone for 30 min (THANKS!!!).

When they replaced the PDC they must have shorted out the new one when they hooked it up (or when doing the alternator).

N3 fuse/breaker was blown. Since N4 is unused, you can move the wire from N3 to N4 and that fixed it. Error gone, warning light off, and ESS works normally (Aux still disconnected with 42 fuse out).

I had assumed that with the 42 fuse pulled and the Aux ground disconnected that the whole N3 etc wouldn't make a difference, but it does.

I need to replace the fuse bar, likely will take it back and make the dealer do it since they charged for a whole PDC.

Leaving Aux disconnected for now since it is likely bad (but Rhinebeck01 says you can't rely on the parking lot load test). I may just get a new Aux and be done with it (I do actually like having the ESS working....)

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