Jumperless Aux Battery Bypass

[jludave]

I am to not sure on removing the fuse first.

Fuse needs to be pulled first.

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[Ben-Zair Dun-Zatt]

jludave, i just saw your post. Thanks for the help on this. ?

 

[Sajeep]

I just bought a new main(house) battery. Then I removed the f42 fuse then removed and taped up the neg wire that goes to the aux battery off the main battery. Still getting lights on dash. I don’t wanna start draining new battery what am I doing wrong ? Thanks

 

[jludave]

Still getting lights on dash.

Have you actually hit the button on the center stack to turn off ESS (Stop/Start)? You should do that every time the vehicle starts, unless you have a Tazer or other module to remember the button state.

Also, make sure the IBS sensor (the one with the red and orange wires by the battery terminal) is fully seated.

Lastly, you might need to pull the other negative cable for a few moments to reset everything in the vehicle. I know it is a pain sometimes (radio and UConnect settings), but it is worth a shot.

 

[Sajeep]

Will do. Thanks

 

[jludave]

what am I doing wrong ?

I just noticed your forum join date. Is your vehicle a 2018 model year?

If so do you know if you have TSB 18-092-19?

This is from an earlier post in this thread:

"If your 2018 is one of the older ones, and doesn't have TSB 18-092-19 applied you will not be able to crank.

If TSB 18-092-19 has been applied then your first attempt at cranking will fail, but your second will attempt to crank off the main battery only. If successful, the vehicle will turn off ESS and tell you so in the EVIC.

All subsequent cold cranks will occur off the main battery but will test for the presence of an Aux battery as well. If a working Aux battery is re-cabled back into your JLs electric circuits, the next cold crank should turn off the ESS off light and restore the crank to the default factory behavior."

 

[Sajeep]

I have no idea if my model is aTSB 18-092-19 or not. Guess my question at this point is the aux battery still pulling juice off my main battery? I just don’t wanna drain a new battery . Thank you for all your help

 

[jludave]

I have no idea if my model is a TSB 18-092-19 or not.

This question isn't if your model is that TSB, it is whether you had the TSB performed on the vehicle by your dealership. A TSB is a service bulletin that is applied to the vehicle to address an issue. If you brought your vehicle in to the dealer for service in the past, it should have been applied. Check your dealer service records, if you have any.

Guess my question at this point is the aux battery still pulling juice off my main battery?

It shouldn't be if you pulled the correct fuse and disconnected the correct cable.

 

[Sajeep]

Think I got it I just unplugged the main negative for the main battery to reset everything and reconnected . Thanks for all the time and info. Fingers crossed

 

[OldGuyNewJeep]

I just noticed your forum join date. Is your vehicle a 2018 model year?

If so do you know if you have TSB 18-092-19?

This is from an earlier post in this thread:

"If your 2018 is one of the older ones, and doesn't have TSB 18-092-19 applied you will not be able to crank.

If TSB 18-092-19 has been applied then your first attempt at cranking will fail, but your second will attempt to crank off the main battery only. If successful, the vehicle will turn off ESS and tell you so in the EVIC.

All subsequent cold cranks will occur off the main battery but will test for the presence of an Aux battery as well. If a working Aux battery is re-cabled back into your JLs electric circuits, the next cold crank should turn off the ESS off light and restore the crank to the default factory behavior."

TSB 18-092-19 Needed so Jeep will crank on second try if AUX is dead. Don't say ESS because that TSB doesn't mention it. Say the A/C fan is too loud.

 

[ErAcEr]

@Rhinebeck01 or Anyone else with info.

I tried using the search function to find what is the best replacement for our main battery. If anyone has info can you point me to it? Thanks. My main finally died this morning, and I have a battery jump pack so I can get places however Ill need to put a new juicer in asap. TIA

 

[Rhinebeck01]

@Rhinebeck01 or Anyone else with info.

I tried using the search function to find what is the best replacement for our main battery. If anyone has info can you point me to it? Thanks. My main finally died this morning, and I have a battery jump pack so I can get places however Ill need to put a new juicer in asap. TIA

https://www.jlwranglerforums.com/forum/threads/🔋🔧-main-battery-replacement-talk-jl-jt-🪫.100534/

 

[DWS44]

Just wanted to pop in and say thanks to @Jebiruph , @Rhinebeck01 , and others who've contributed on this long thread. I had been rolling around with the "Service Start/Stop" warning staring at me for at least a couple months dreading tearing it apart and replacing the aux again. (2018 JLR)

Finally had some time to research and found this post. Today, I pulled the fuse, disconnected the aux negative cable and the Jeep still fired right up like normal. Then I went back and disconnected the main negative, while I taped up and heatshrinked the aux negative, to allow it to clear the service" warning. Hooked the main negative back up, service error gone, and still runs like a champ! Ordered the recommended SmartStartStop module which should be here on Monday to complete the work. (My only goof in the whole process was missing the fact you could PM the seller on the forum here and get a discount. Didn't see that till I had already ordered. Doh! lol)

All in all, good stuff here and no longer have to worry about the dang thing...thanks again! ?

 

[Tyler-98-W68]

Absolutely fantastic write up on the ESS stuff @Jebiruph I've been following this with intrigue and while I had a Wrangler (well 2 4xes) I"ve never owned a ESS dual battery equipped vehicle. I do now however have a 23 Grand Cherokee Laredo with the dual battery ESS system.

The whole premise and function is the same as you have outlined obviously the wiring and schematics are a bit different.

Here is my question about bypassing the Aux battery in the least invasive way possible.

I've always had a fascination with Lithium batteries and was thinking about installed a lithium battery to replace the Aux 14 battery. (I already have a large automotive grade lithium battery)

However that won't just work because its resting voltage is higher and will drain itself completely trying to charge the main battery while the vehicle is off. It would however work as a back up to jumpstart the main battery if needed.

So my question is this.

Can one simply pull the F42 fuse (which I haven't figured out which one it is in the WL Grand Cherokee) and then instead of disconnecting the negative cable on the aux, simply wire a battery disconnect switch?

I've seen your previous posts about wiring a disconnect with gauges ect.....not looking for something that elaborate (it really isn't but I don't need to monitor the battery as it's got built in monitoring)

Thanks for your time and all the work involved with this ESS system.

 

[jludave]

Can one simply pull the F42 fuse (which I haven't figured out which one it is in the WL Grand Cherokee) and then instead of disconnecting the negative cable on the aux, simply wire a battery disconnect switch?

Simple answer, yes. The goal is to have the aux battery disconnected. It doesn't matter how you do it.

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