3.6L ESS Aux Battery Bypass

[Pahrump Geprge]

@Pahrump Geprge

Huh........ please explain. Why .... because if you use a jumper, you do not need to pull F42 fuse.

I was not real clear in my statement. I removed the jumper cable fuse, thus no need to pull F42 fuse.

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[Rhinebeck01]

I was not real clear in my statement. I removed the jumper cable fuse, thus no need to pull F42 fuse.

@Pahrump Geprge

So, you are saying you used an N1 to N2 fused (40 amp fuse) bypass jumper and you disconnected the Aux negative cable that resides on the Main battery negative side?

 

[Pahrump Geprge]

@Pahrump Geprge

So, you are saying you used an N1 to N2 fused (40 amp fuse) bypass jumper and you disconnected the Aux negative cable that resides on the Main battery negative side?

No, I did not disconnect anything. Permanently installed the N1/N2 jumper with fuse removed.

 

[Rhinebeck01]

No, I did not disconnect anything. Permanently installed the N1/N2 jumper with fuse removed.

@Pahrump Geprge

You are in error in regard to what you are doing. Unless, I am misunderstanding what you did...

Do some more forum research..
You'd want to use an N1 to N2 fused (40 amp fuse) bypass jumper and you'd disconnect the Aux negative cable that resides on the Main battery negative side.

Either the above... or no jumper and pull F42 along with disconnecting the Aux neg cable on the neg. side of the Main battery.

Not what you are saying you did/are doing.

 

[CdnJL]

2018 JLU with 02/18 build date.

Tried N1/N2 jumper with Aux negative disconnected, no start but interior electronics function with main battery tested at normal voltage.
Tried F42 fuse with Aux negative disconnected, same no start condition, same functioning interior electronics.

Jumper used is a 50amp fuse with 8 gauge. Suggestions on why this won't work but does for other 18JL's trying this AUX Battery bypass and same N1/2 terminals? Thanks all!

 

[Leisure Freak]

In reply to CdnJL. There was a software (firmware) update needed by dealer on many 2018 JLs. 2019 and later all came with it that which allowed the JL to start without having to pass the Aux Battery test. Has yours had that update? I don't know the actual update number/details but I am sure you can do a search for it.

 

[Fudster]

2018 JLU with 02/18 build date.

Tried N1/N2 jumper with Aux negative disconnected, no start but interior electronics function with main battery tested at normal voltage.
Tried F42 fuse with Aux negative disconnected, same no start condition, same functioning interior electronics.

Jumper used is a 50amp fuse with 8 gauge. Suggestions on why this won't work but does for other 18JL's trying this AUX Battery bypass and same N1/2 terminals? Thanks all!

John: I'd first rule out a bad main battery by having a load test effected on it. How old is this battery? I hope not from 2018. If so, even if it still tests fine, time suggests it preventatively be replaced.

 

[Jebiruph]

2018 JLU with 02/18 build date.

Tried N1/N2 jumper with Aux negative disconnected, no start but interior electronics function with main battery tested at normal voltage.
Tried F42 fuse with Aux negative disconnected, same no start condition, same functioning interior electronics.

Jumper used is a 50amp fuse with 8 gauge. Suggestions on why this won't work but does for other 18JL's trying this AUX Battery bypass and same N1/2 terminals? Thanks all!

Maybe not a battery issue. You can try disconnecting the main battery and starting with the aux only. You can also try disconnecting both batteries for awhile to reset the electronics.

 

[CdnJL]

This all started with the notorious Start/Stop function error on the dash, then overnight Jeep wouldn't start. I already knew about Aux bypass tricks. Boosted and driving fine with error light on. Main battery tested and charged just fine.

Did F42 fuse trick, same no start condition. Disconnecting the Aux negative lead, the assembly that attaches to the negative battery terminal was a quarter turn loose which I tightened and hooked up the jumper as described here. Clickety click, non starting Jeep.

Reconnected and since Jeep was just driven, main battery was charged and Jeep started up fine. No error lights anymore and it all starts fine since. Both batteries are reading fine with voltmeter. Suspect is loose terminal connection assembly on the negative possibly not getting enough contact. Still tried jumper trick to avoid being stranded if Aux battery craps out and no start condition and from drawing down Main overnight. Jeep doesn't start when I do this taking me back to starting this question.

Original main battery as of right now and will ask dealer this afternoon about ESS flash. But still, why doesn't N1/N2 work here?

 

[Jebiruph]

This all started with the notorious Start/Stop function error on the dash, then overnight Jeep wouldn't start. I already knew about Aux bypass tricks. Boosted and driving fine with error light on. Main battery tested and charged just fine.

Did F42 fuse trick, same no start condition. Disconnecting the Aux negative lead, the assembly that attaches to the negative battery terminal was a quarter turn loose which I tightened and hooked up the jumper as described here. Clickety click, non starting Jeep.

Reconnected and since Jeep was just driven, main battery was charged and Jeep started up fine. No error lights anymore and it all starts fine since. Both batteries are reading fine with voltmeter. Suspect is loose terminal connection assembly on the negative possibly not getting enough contact. Still tried jumper trick to avoid being stranded if Aux battery craps out and no start condition and from drawing down Main overnight. Jeep doesn't start when I do this taking me back to starting this question.

Original main battery as of right now and will ask dealer this afternoon about ESS flash. But still, why doesn't N1/N2 work here?

Somethings seems off, it's not eTorque is it? Instead of N1/N2, try main positive to N1. Post some pics.

 

[CdnJL]

no eTorque. Thanks! Will try, please hold......

 

[jeepdabest]

2018 JLU with 02/18 build date.

Tried N1/N2 jumper with Aux negative disconnected, no start but interior electronics function with main battery tested at normal voltage.
Tried F42 fuse with Aux negative disconnected, same no start condition, same functioning interior electronics.

Jumper used is a 50amp fuse with 8 gauge. Suggestions on why this won't work but does for other 18JL's trying this AUX Battery bypass and same N1/2 terminals? Thanks all!

Did you get the software update

 

[CdnJL]

Was at the dealer yesterday for other non electrical issues, scanned and no applicable update for ESS came up for mine. I'm in Canada and maybe build date for mine didn't warrant one.

 

[Jebiruph]

Was at the dealer yesterday for other non electrical issues, scanned and no applicable update for ESS came up for mine. I'm in Canada and maybe build date for mine didn't warrant one.

The update fixes multiple issues, but doesn't mention ESS. After I got the update I tested the ESS problem and found it was also fixed.

 

[CdnJL]

Ahh ok. Thanks! I'll dig up TSB that others are quoting here and give it to my dealer for a more specified search on their end. Their service dept is the best i've experienced, more so than some higher end german vehicles i've owned. Mine is going in for the Spark Knock TSB shortly, trying to get all issues sorted on same visit.

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