Jumperless Aux Battery Bypass

[Mguy]

I cut off a piece of bike inner-tube to attach with zip tie to the disconnected aux neg cable end to protect it from hitting ground and be able to peel it back like a foreskin to get to it for charging.

Rubber/vinyl hose as insulator, easily removable.

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[damageinc321]

So my battery went dead while I was out of town in December, I couldn't jump start it so I put it on charger thru fuse box terminal and battery. It started up and ran fine, so because this is the second time in 2 years I decided to pull the negative cable off the aux battery and pull the f42 fuse. No problem since, but know I have smog testing and it keeps saying o2 sensor not ready. Is it possible that not have that battery can impact those readings.

 

[Leisure Freak]

So my battery went dead while I was out of town in December, I couldn't jump start it so I put it on charger thru fuse box terminal and battery. It started up and ran fine, so because this is the second time in 2 years I decided to pull the negative cable off the aux battery and pull the f42 fuse. No problem since, but know I have smog testing and it keeps saying o2 sensor not ready. Is it possible that not have that battery can impact those readings.

I don't know for certain, but this is my experience and what Jeep Service told me. I lost battery/power and after battery replacement got P0456 ChkEngineLight EVAP Sys. After clearing the CEL with my OBD2 scanner it stayed in not ready state for a long driving cycle of miles/days. That would have kept me from passing an emissions test. Based on info on this forum I saw an available PCM flash 68440959 for early JLs (mine is a 2019) throwing that code at power loss. I did get the flash but was told by service that it may still throw that code or any other at battery power loss because the PCM may still land on something. So my answer is, Maybe?

 

[THAW]

So my battery went dead while I was out of town in December, I couldn't jump start it so I put it on charger thru fuse box terminal and battery. It started up and ran fine, so because this is the second time in 2 years I decided to pull the negative cable off the aux battery and pull the f42 fuse. No problem since, but know I have smog testing and it keeps saying o2 sensor not ready. Is it possible that not have that battery can impact those readings.

Bypassing the Aux/ESS battery has no direct effect on O2 sensors.

Low system voltage from a falling battery can cause issues resulting in check engine lights and codes even when systems are in working order.

 

[Geoarch]

Bypassing the Aux/ESS battery has no direct effect on O2 sensors.

Low system voltage from a falling battery can cause issues resulting in check engine lights and codes even when systems are in working order.

For those concerned about warranty, I would be concerned: 1) that the AUX after disconnect would simply die over time, and 2) the dealer would get upset, not that I care about the latter. So, if it was dead over time since it wouldn't be charging while disconnected, then it might immediately drag down the main, and then what? I guess you could charge it periodically, or just remove it and hope that the dealer either wouldn't care of wouldn't notice. I do have a greedy dealer.

 

[jludave]

So, if it was dead over time since it wouldn't be charging while disconnected, then it might immediately drag down the main, and then what?

It can’t drag down the main if it is no longer connected and the fuse is pulled. That’s the entire point of doing the bypass. The vehicle essentially only has one battery at that point.

hope that the dealer either wouldn't care of wouldn't notice. I do have a greedy dealer.

I recently had my vehicle at the dealer for an annual state inspection. I did not reconnect my aux battery nor replace the fuse. The aux battery is still in place. I didn’t mention anything about it. They didn’t notice, care or say anything.

 

[Geoarch]

It can’t drag down the main if it is no longer connected and the fuse is pulled. That’s the entire point of doing the bypass. The vehicle essentially only has one battery at that point.



I recently had my vehicle at the dealer for an annual state inspection. I did not reconnect my aux battery nor replace the fuse. The aux battery is still in place. I didn’t mention anything about it. They didn’t notice, care or say anything.

That's good news. I'm one of those that was stranded on the freeway with a 19th month old JTR after the AUX went. I have a 2024 JTR coming and will disconnect it this time.

 

[Magredvet]

On Friday I joined the "no start" Wrangler club, with the vehicle less than 3 yrs old. Obviously the original Mopar batteries are POS', so I'm going the H7, aux batt isolation route. I have one question for those who have done it on a 21 up, which has the main ground as M8 and the terminal on the IBS as M6. Did you just put the M8 sized lug on the main ground cable, onto the M6 IBS sensor, or did you fab a bracket with both M6 and M8 sized holes, to keep from having any slop, with the M8 hole on the M6 stud ?
TIA

 

[Go Hogs!]

On Friday I joined the "no start" Wrangler club, with the vehicle less than 3 yrs old. Obviously the original Mopar batteries are POS', so I'm going the H7, aux batt isolation route. I have one question for those who have done it on a 21 up, which has the main ground as M8 and the terminal on the IBS as M6. Did you just put the M8 sized lug on the main ground cable, onto the M6 IBS sensor, or did you fab a bracket with both M6 and M8 sized holes, to keep from having any slop, with the M8 hole on the M6 stud ?
TIA

I just did this on my ‘22 yesterday. I just put the m8 over the m6 and tightened it down snug. No problems. I also plan on leaving the abandoned aux battery in place in the jeep.

 

[Magredvet]

Thanks for the info.....makes it simple....?

 

[Go Hogs!]

Thanks for the info.....makes it simple....?

your radio will be in a reduced state initially. No Sirius, climate controls reduced to only hi and lo settings, etc. push and hold power and enter buttons for ten seconds and then release. Everything should then return to normal.

 

[damageinc321]

So my battery died in December after being replaced a year or so ago, so after putting a charger on it thru the fuse box to charge both batteries I was able to start it, so after I got everything working I pulled neg cable on aux battery and pulled f42 fuse, since then everything has been fine no problems or codes. Now I have smog testing and it's failed for an o2 sensor. I reconnected the cable and fuse and had it re flashed by the dealer. It's still failing even though all sensors appear to be working when I look at the scan tool data. The battery was showing 51 percent state of charge, is it possible that is the issue?

 

[AndySpill]

your radio will be in a reduced state initially. No Sirius, climate controls reduced to only hi and lo settings, etc. push and hold power and enter buttons for ten seconds and then release. Everything should then return to normal.

Are you saying this due to the absence of electrical current in the vehicle during this main battery change?

If so, wouldn't swapping the main battery, connecting it, and then isolating/insulating the negative cable from the Aux battery, in that order, never deprive the vehicle of electrical current?

I may misunderstand your thought process.

 

[Go Hogs!]

Are you saying this due to the absence of electrical current in the vehicle during this main battery change?

If so, wouldn't swapping the main battery, connecting it, and then isolating/insulating the negative cable from the Aux battery, in that order, never deprive the vehicle of electrical current?

I may misunderstand your thought process.

It was not possible to isolate the aux without disconnecting both negative connections on my ‘22 model.

 

[Magredvet]

your radio will be in a reduced state initially. No Sirius, climate controls reduced to only hi and lo settings, etc. push and hold power and enter buttons for ten seconds and then release. Everything should then return to normal.

K did the deed, easy, as you said, however I have not got my AC back fully yet after 2 ign cycles. Which buttons did you press for 10 secs ?
You say the radio on button and the enter button ? Which is the enter button ? I tried the one with "browse" on it, however that didn't work.....?
I may be just old and/or stupid.....?



I'm an idiot....just noticed it has enter, under the browse.......?

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