Failed attempt to disable aux battery

[homebrew]

21 Eco Diesel. Jeep wouldn’t start so took to dealer. They tested it and said both batteries were bad and would not cover under warranty due to my accessories.

I went and bought a new battery and installed it. I disconnected the auto start ground and pulled fuse 42. When I started the jeep the air bag light was on and I had no Sirius radio. I was still at the dealer and asked them to pull the codes. Came back with an ignition circuit error code. I put the fuse back in and left the ground disconnected. Jeep started and the air bag code was gone and still had no Sirius . Is there another way to bypass the aux battery so I don’t have to replace it?

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[DwnSth]

2021 ecodiesel. Same thing almost. Disconnected aux ground and fuse 42. Ran fine for over a week then simply died. All power gone. Put a new aux battery in and reconnected ground and 42. Also replaced fuse array thinking I had shorted something out (old one tests good). All running perfect again. Several jeep expert mechanics have told me don't eff with the aux. No one really knows how this is wired and what programming it's related to. I was getting crazy voltage readings until I put all back. Until there is a perfect solution I'm keeping the damn thing and just disabling the auto start/stop.

 

[Plongson]

2020 here, aux has been GONE about two years. Just replaced the main battery before a five week road trip 'cause it was over 4 years old.
No problems EVER, never looked back. Ya just might question the "expert" jeep mechanics opinion...someone evidently did something wrong. There is WAY too many examples of the auxiliary battery being successfully removed for just two of you having problems.
I'm thinking "pilot error".

Not casting aspersions, JMO. The battery is the source of power, if done correctly, the Jeep has no clue where the 12vdc power is coming from...one battery or two.

 

[BDinTX]

You may have popped a fuse in the fuse array when working in there. Not certain it would cause your problem or not but worth a check.
https://www.jlwranglerforums.com/forum/threads/alert-high-amp-fuse-array-related.65085/

After about a year of running my 21 ED without the aux battery, I actually cut the end of the cable off when I found the rubber tape protecting it was degrading.

When I replace my main battery I intend to pull the aux battery and it’s cable out entirely.

 

[jludave]

I disconnected the auto start ground

You mean the aux negative? Please clarify exactly what you removed. It sounds like you did something wrong. Check the thread below for what you should do.

https://www.jlwranglerforums.com/forum/threads/jumperless-aux-battery-bypass.95945/

 

[SargeDiesel]

2021 ecodiesel. Same thing almost. Disconnected aux ground and fuse 42. Ran fine for over a week then simply died. All power gone. Put a new aux battery in and reconnected ground and 42. Also replaced fuse array thinking I had shorted something out (old one tests good). All running perfect again. Several jeep expert mechanics have told me don't eff with the aux. No one really knows how this is wired and what programming it's related to. I was getting crazy voltage readings until I put all back. Until there is a perfect solution I'm keeping the damn thing and just disabling the auto start/stop.

This.

People are very quick to blame the batteries for everything Jeep related, I agree , they have their issues, but damn not everything is the battery's fault.

I plan on leaving mine alone and when it's time to replace I will just upgrade with the best options possible.

I do have the original smartstopstart, so either I've been lucky or this has something to do with it, but my batteries have been good so far.

To the OP, I would go to a different dealership.I cannot see why they would not honor the warranty because of accessories but if you have some that are easily disconnected, disconnect them and hide the wires before you go to the next dealership.

Many people on the forums have had their batteries replaced and I'm sure at least some of them had accessories.

 

[Da Capt]

If I remember right the aux battery has written in it a 36 month free replacement

 

[JLUR Farout]

Do not mess with fuses. Remove main battery, remove aux battery, label terminals as they look very similar. Reinstall aux battery lid box, reinstall main battery, bolt aux terminals to main battery terminal. 38,000 miles doing this and zero issues.

 

[Deleted Member RoadNomad]

Many people forget to check to make sure all fuses and relays are properly seated in the fuse center. A fuse that is not properly seated can cause all kinds of crazy problems.

It only takes a few minutes to pop the top off the fuse center and give them all a push.
You might be surprised how many you will find that aren't all the way in.

 

[GtX]

Do not mess with fuses. Remove main battery, remove aux battery, label terminals as they look very similar. Reinstall aux battery lid box, reinstall main battery, bold aux terminals to main battery terminal. 38,000 miles doing this and zero issues.

Pulled the fuse, discoed the cable, over a year ago. Aux is dead weight now.

 

[Ratbert]

Do not mess with fuses. Remove main battery, remove aux battery, label terminals as they look very similar. Reinstall aux battery lid box, reinstall main battery, bold aux terminals to main battery terminal. 38,000 miles doing this and zero issues.

No lights on the dash?

 

[THAW]

No lights on the dash?

Connecting the Aux/ESS battery positive terminal connector to the main battery positive terminal shouldn't cause any dash lights. Doing so creates a direct path between N1/system electronics and the main battery so the open/close state of the PCR is irrelevant (thus, no need to pull fuse F42).

 

[Deleted User 38384]

I did exactly what this guy did in his video:



Mine works just fine. With fuse F42 in, the start/stop will occasionally activate, and with fuse F42 out, it'll just tell me that the battery is charging forever, but it will never charge enough to activate.

Only downside I have noticed is that occasionally with fuse F42 out, my Jeep will occasionally not start at all. And then the second I put fuse F42 back in, it starts up fine. Usually I'll run it with fuse F42 out and then when it decides it doesn't want to start, I'll put fuse F42 in, run it for a week and then pull it out again.

 

[JLUR Farout]

No lights on the dash?

Nope. 40,000 miles. Not a problem.

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