bigfoot21075
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THANKS!! So if one simply disconnects the small battery it will cause issues correct?
On a side note, I appreciate your contributions. Even as an old hot rodder I still learn a ton from your posts.
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On a side note, I appreciate your contributions. Even as an old hot rodder I still learn a ton from your posts.
Slippery Pete
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My Jeep was built in mid June (22) and picked up late June. How do I know which method to use?
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Agreed, but I don't think that the TSB (i.e. TSB 18-092-19) is even relevant here. This software patch, at least as it relates to the functionality of dual AGM battery JLs, and built into all of them barring some of the early 2018s (which expressly need it dealer downloaded) deals (in part) with how the vehicle handles a dead *factory wired* Aux battery.@Slippery Pete
You should be able to use either method.
Guys/gals here regardless of model year and or if they had the TSB done on their early in model year 2018 built JL have reported using both methods.
Try the jumper less method. No harm trying. You can't screw anything up, lets say.. If that does not do the deed just spend the $8-9 and go with the N1 - N2 fused (40 amp) bypass jumper.
(*factory wired: neither the jumper of this thread installed, nor Fuse 42 pulled)
As I understand it, dual AGM battery JLs isolate the Aux battery for an instant at cold crank to test it. Otherwise, the batteries are always in parallel except for ESS events.
If at this point in the cold crank, if the Aux battery is dead, so too is your early model dual AGM battery JL. But with the TSB, subsequent user attempts to cold crank will be done by the vehicle solely off the main battery. If successful, the Aux battery is bypassed and the "ESS off" light is illuminated in the EVIC until the next cold crank (if any) where a factory wired and energized ESS battery is detected, or the vehicle thinks this the case with the jumper or Fuse 42 solution.
When the jumpering approach is taken the batteries are hard wired in parallel at all times. So the pre-crank test of the Aux battery really becomes a test of both batteries together.
And in the Fuse 42 pulled approach, the same prevention of isolation of the ESS battery effect happens, but for different reasons: namely because a relay that separates the batteries is disabled rather than in the jumper approached where the jumper's short circuit physically prevents such isolation.
Same effect, different means.
I'd also agree that there's little harm in trying either approach but think it a good idea to turn ESS off. With either the jumper of Fuse 42 pull, no longer will your main battery be isolated in ESS events to preserve its power for post ESS event engine cranking.
You'll probably be fine: many vehicles run one battery ESS systems. I'd just hate someone to get stranded in the left hand turn lane during a JL one battery ESS event, if you catch my drift.
All this said, I think, if your running TSB 18-092-19, that both the jumper and Fuse 42 approach are best if you hate EVIC notices. If not, pull the black cable from the Aux battery's negative terminal that leads to the main battery's negative and electric tape up its loose end. (Two factory cables tie into the main battery's negative terminal. Leave alone the one whose other end attaches to the body ground on the passenger's side front quarter panel.)
Try to crank. Fail. Try again. If your main battery has power the vehicle will turn ESS off for you--you never have to remember of buy tech to do it. All subsequent cold cranks will happen successfully on the first attempt, against only the main battery, as long as your main battery has juice. As mentioned prior, only reconnection of an energized ESS battery, on the next cold crank will revert back to factory behavior.
But you will have that EVIC notice that jumpering or Fuse 42 pulling will avoid, much as these latter two approaches will make turning ESS off up to you.
I think it's personal preference rather than an one way best situation.
txj2go
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I have a 2018, I don't know if it is early or late. It has apparently been reflashed by the dealer before I got it. The ESS light has been on since the day I got it. I would have complained to the dealer but they are 100 miles away and I didn't care if ESS functioned or not.
I read pages and pages of threads here and found that I could disconnect the small battery and test to see if I had the reflash so I did that. Everything worked fine so it has been disconnected now for almost 2 years. Since ESS doesn't function anyway I don't have the risk of it running the battery down and being stuck somewhere. I think if you add the fuse you run this risk.
I did buy what I thought was the best AGM battery I could buy and installed it before I started doing trips to relatively remote places. I found that the battery in my 3 year old Jeep was only 2 years old so replaced by the dealer for some unknown reason.
I read pages and pages of threads here and found that I could disconnect the small battery and test to see if I had the reflash so I did that. Everything worked fine so it has been disconnected now for almost 2 years. Since ESS doesn't function anyway I don't have the risk of it running the battery down and being stuck somewhere. I think if you add the fuse you run this risk.
I did buy what I thought was the best AGM battery I could buy and installed it before I started doing trips to relatively remote places. I found that the battery in my 3 year old Jeep was only 2 years old so replaced by the dealer for some unknown reason.
Rhinebeck01
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I completely agree that Jerry, @Jebiruph , as founder of both the jumpered and fuse 42 technique, is the source for these two methods, much that they've been well covered by others in this thread.
The thing though, as stated, is that there are 3 approaches as far as I know. The 3rd, for dual AGM battery JL owners with TSB 18-092-19 (i.e. most owners,) where the negative cable from the Aux battery is separated from the main battery's negative post, with its end insulated, automatically turns off ESS where Jerry's don't.
Some may hate that this is done with an "ESS off" light in the EVIC, associating such lights mentally with vehicle problems. They should certainly use one of Jerry's techniques or live with ESS, 2 batteries and trickle charging (my setup, so I have no "horse" in this "abandon the Aux battery turn ESS off" camp.)
But some who do without the Aux battery (and who should turn ESS off) may not mind this EVIC message. Some may even take comfort, running 1 battery, with the message's assurance that ESS won't (and shouldn't) engage. For those, not having to press the ESS off button every time they cold crank, or buy tech to do this is time and money saved for another Wrangler accessory.
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sweet88gt
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Thanks for the replies. The Jeep on Tuesday wouldn't start for work. Removed the Negative terminals (both) reattached and quickly went to start and it did fire off. Drove it to dealership and dropped it off. Tuesday evening I returned to pick it up and they only replaced the Aux battery. They left the Main battery as is.
I get it they only get paid for tests performed which failed but I was under the impression it would have been better to replace both. It is what it is since warranty is involved. Ill take it running over the alternative.
I get it they only get paid for tests performed which failed but I was under the impression it would have been better to replace both. It is what it is since warranty is involved. Ill take it running over the alternative.
aldo98229
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Let us know what happens after the dealer replaced only the auxiliary battery.
I’ve seen posts by JL owners who ended replacing both batteries after replacing only the auxiliary battery didn’t fix the problem. Curious if that’s always the case or not.
Good luck.
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sweet88gt
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Going to revisit this once again.
The Aux switches not available twice in the last week. Now I need to unmarry the Tazer and send it back to the shop.
Im sure its going to drive like crap from the house to the dealer. About 1 month left on warranty.
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sweet88gt
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So story is on 11-8-2022 I took the Jeep in for battery issue. They replaced the Aux battery alone. This past week or so I have had the same warning of Aux switches not available. I just called to get it back in and was told I don't drive enough to charge the battery.
I have 22,xxx miles currently. Purchased May of 2020. I get it that I don't drive it a lot but for the battery to have the same issues 5 months later ? Service advisor told me to drive it more I would be fine.
Here we go.
I have 22,xxx miles currently. Purchased May of 2020. I get it that I don't drive it a lot but for the battery to have the same issues 5 months later ? Service advisor told me to drive it more I would be fine.
Here we go.
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Roky
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STW
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you don't have to remove the Aux, just do the "jumperless Aux battery bypass."
you pull fuse 42 and remove the Aux negative cable (tape away out of trouble). Your Aux is now out of the loop and will use the main battery only.
https://www.jlwranglerforums.com/forum/threads/jumperless-aux-battery-bypass.95945/
And your dealer is wrong to tell you you don't drive enough. Jeep just designed a dual battery system with inadequate system control and charging conditions. Driving a lot of miles, and often, probably prevents it because there's enough charging time to make up for their design inadequacy. But your driving is not the issue. Their design is the issue.
Shibadog
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Ain’t it amazing? Cars started and worked just fine for over 100 yrs with one battery. Then someone decided we need start/stop to save fuel. Let’s see, we can add a stronger battery or Wait, I’ve got a great idea, let’s put a motorcycle battery in with extra wiring. What could possibly go wrong??
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