Another ESS/Battery Question

[Panthers65]

Lot of info going back and forth. You most likely saw the low voltage while still plugged in was because of the resitance of the main battery power leading its was back instead of coming from the AUX battery. That voltage was realistically much lower. Also you did the right thing by bypassing the battery. as long as you also jumped N1 to N2 or N3 i always forget. The system will say not ready charging till the IBS is above 70%. This will happen over time while the vehicle is running and while sitting undisturbed for hours. If the main battery is good and charged, the sensor will read correctly by the morning

Instead of jumping N1 to N3 I removed the F42 fuse per this website

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

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[exfil offroad]

I've ready several of the other threads out there about the Main/Aux Battery, but can't find anything specific to my situation.

'21 Sport S with a S-Tech switch box and a winch. Gladiator was delivered November '21, so 14 months old, and when it was delivered there was an issue with the ESS and the dealership replaced the Aux Batter before I took delivery. ESS worked fine for about a year, and stopped working a month or so ago. Secondary vehicle, a lot of around town trips which I know is rough on a battery.

Getting a plain "Engine Start/Stop Not Ready" message, no other messages/reason.

Engine off, last drove it for a few miles last night:
Voltage across the main battery- 12.4-12.5
Voltage at the N1 Terminal- 11.6

Engine on, right after start:
Voltage across the main battery- 14.7
Voltage at the N1 Terminal- 14.7
Voltage on the dash screen- 14.6

After letting the truck idle for 10 minutes and come to temp, all the voltages are the same , maybe .1V higher. With the switches and winch, I figured the dealership might hassle me about warranty work, so if it's just the Aux battery I'd likely just replace it or bypass it all together myself. Given the low voltage on the N1 terminal with the engine off, and the running voltage staying at 14.7, that would be my assumption. Can anyone confirm if I'm on the right track?

in my experience with a JT and JL your auxillary battery is dying, its still operating but not reaching a full charge which will cause it to permanently stay in charging status. The final to it all will be when your aux buttons are no longer available due to it. People will dispute this but its been the story on both my 2018 JLUR and 2021 JT. The fix was to replace the aux battery. 15-20 minutes and youll be on your way.

 

[Panthers65]

in my experience with a JT and JL your auxillary battery is dying, its still operating but not reaching a full charge which will cause it to permanently stay in charging status. The final to it all will be when your aux buttons are no longer available due to it. People will dispute this but its been the story on both my 2018 JLUR and 2021 JT. The fix was to replace the aux battery. 15-20 minutes and youll be on your way.

Thanks, I've watched that video and did the aux batter delete. I took it for a short drive, but it didn't fix the ESS. Also, I have S-Tech switches because my gladiator didn't come factory with the Aux Buttons.

Just to be clear- I couldn't give two craps about the ESS system, but if it's a symptom of a larger issue I don't want to get stranded. The Aux battery killing my main battery and leaving me stranded would piss me off way more than the dumb ESS system never working again.

 

[exfil offroad]

Thanks, I've watched that video and did the aux batter delete. I took it for a short drive, but it didn't fix the ESS. Also, I have S-Tech switches because my gladiator didn't come factory with the Aux Buttons.

Just to be clear- I couldn't give two craps about the ESS system, but if it's a symptom of a larger issue I don't want to get stranded. The Aux battery killing my main battery and leaving me stranded would piss me off way more than the dumb ESS system never working again.

Oh I see what your saying... I dont know why you would break down essentially, something is just not reading pertaining to the ESS. But if you dont have the stupid motorcycle battery, I would not think its draining your primary, rather not communicating correctly.

 

[ShadowsPapa]

Also you did the right thing by bypassing the battery. as long as you also jumped N1 to N2 or N3 i always forget.

No need. He did the jumperless bypass. All you need to do is remove the aux ground cable from the IBS, (wrap it, whatever) and pull F42 which prevents the PCR from opening.
Jerry has posted great info on that. It's fast, it's simple.
The main battery powers the N1 electronics just fine that way.

Not running, the load of the electronics isn't enough to drop the voltage that much from the main battery to N1. Not unless there was an issue with the PCR or the aux battery.
That wiring can handle multiple amps - a running load, so it can handle a truck sitting not running, just powering the basic electronics while the rest is off. This is proven by Jerry's jumperless aux battery bypass. All power to N1 is going from the main battery positive, through the PCR and then to the N1 terminal and life is fine.
If there's that much resistance, he's got a problem. It certainly won't drop voltage that much normally. Not without something being bad.
Otherwise, with the jumperless bypass, you'd lose the ability to run the HVAC fan, radio and other "stuff". It would all be suffering low voltage. I'd bet that wiring could handle 20-30 amps at least. That means the voltage drop would be negligible with the truck shut off under normal conditions.

 

[ShadowsPapa]

Instead of jumping N1 to N3 I removed the F42 fuse per this website

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

YOU did it right if you followed Jerry's ( jebiruph ) bit - he posted about exactly how to do it in this forum months ago.
NO NEED to jump anything!

 

[ShadowsPapa]

Oh I see what your saying... I dont know why you would break down essentially, something is just not reading pertaining to the ESS. But if you dont have the stupid motorcycle battery, I would not think its draining your primary, rather not communicating correctly.

He does have it - he only bypassed it as an experiment - a way to decide if he should dig deeper, turn left, turn right, blow it up, or other.

He's got a problem - that's a heck of a voltage drop. So either he's got an aux battery going south, or a PCR that's going (burned contacts, excessive resistance) or some other wiring factor causing that big of a drop. That wiring is pretty heavy - heavy enough to handle the load of the truck at rest (engine not running, just sitting there, lights off, etc.) so to see that much difference is reason enough, IMO, to pause and do some discovery.
If something totally fails - say N3 fuse burned, aux battery dies, PCR fries, whatever, although it's not a likely thing - it's a good reason to find out WHY it's doing that.
None of this is normal. People "in tune with" their vehicles will ward off problems before they exist.

Even if a person doesn't like ESS - it can be an indicator of other things going on. Battery issues, IBS needing to be reset, wiring issues, fuse issues, stored codes for some other thing going on.

But I guess not everyone is curious as to "why isn't it working". Any time something isn't working, even a feature you hate - since it relies on the rest of the truck being perfect to operate - it's sort of saying - the rest of the truck isn't so perfect right now.

Me - I'd go back to charging each battery, resetting the IBS, going from there with voltage measurements. (only reset the IBS and put it back on fully charged battery. Don't reset it and put it on a partially charged battery)

 

[Radio Guy]

YOU did it right if you followed Jerry's ( jebiruph ) bit - he posted about exactly how to do it in this forum months ago.
NO NEED to jump anything!

And if you choose to jumper N1 to N3 or yank F42, I thought I read where the main battery tray will accommodate a larger series of battery. That seems like the best final solution getting the dinky battery and ESS circuit out of there and putting in a larger capacity main battery that should provide slightly more cranking power and run electronics a little longer without the engine running.

 

[Jeeperjamie]

Had the same thing happen to mine and was getting the same message. Let it go for about 8 or 9 weeks , went out one morning and the jeep wouldn't crank. Got it fired up after jumping it off, went to AutoZone and they told me it was the aux battery dying and not holding charge. Was about to buy a aux battery but decided to go to the dealership since it was going to be a bit of a job replacing it. They did a diagnosis on it and came back with a dead cell in the main battery. The system was showing good voltage on the charging system on the info screen but I was still getting the Stop/Start message still after a jump. They charge a $87 fee but my dealer takes it off the total charge if they replace the battery. Ended up costing me a little over $300 to get it done but piece of mind was worth it to me. Drove it around 50 miles and the ESS kicked in and started working again and I haven't had any more issues and that was 13,000 miles ago.

My guy at the dealer said a lot people come in and think it's the small battery and about 90% of the time it's the main battery that's the problem. I know guys that have north of 100,000 miles on their Aux batteries without replacing them. I'm at 65,500 miles and mine still working.

 

[Andy29847]

I believe this is Jerry's drawing. It is the best one I have seen for our Jeeps.

 

[ShadowsPapa]

I thought I read where the main battery tray will accommodate a larger series of battery.

Depends on your options. If you have factory aux switches, you have the larger battery (700 amp)
No aux switches - smaller battery.
Diesels may be different?

Mine has the largest battery they come with factory. Can't get a physically larger battery in there. It fills the tray. My 2020 didn't have aux switches and had the smaller battery with a bit of room on the end of the tray.

Got it fired up after jumping it off, went to AutoZone and they told me it was the aux battery dying and not holding charge. Was about to buy a aux battery but decided to go to the dealership since it was going to be a bit of a job replacing it.

I'd never let clowns at a part store diagnose anything. Untrained, especially when it comes to dual battery systems.

And yes, much of what's out there is "internet lore" and started by guessing or one person getting into trouble and not jumping correctly and then blaming everything except themselves.
So much out there that's inaccurate, or even just "not quite right".

 

[Jeeperjamie]

Depends on your options. If you have factory aux switches, you have the larger battery (700 amp)
No aux switches - smaller battery.
Diesels may be different?

Mine has the largest battery they come with factory. Can't get a physically larger battery in there. It fills the tray. My 2020 didn't have aux switches and had the smaller battery with a bit of room on the end of the tray.


I'd never let clowns at a part store diagnose anything. Untrained, especially when it comes to dual battery systems.

And yes, much of what's out there is "internet lore" and started by guessing or one person getting into trouble and not jumping correctly and then blaming everything except themselves.
So much out there that's inaccurate, or even just "not quite right".

So true

 

[GEETCH]

Evening yall,
I had my truck at a body shop being repaired from a T-bone collision. The repairs were top notch, can't even tell. However, the shop let the batteries die and i was having ESS faults. I charged the batteries independently, left disconnected for an afternoon while I was running around. Fault cleared everything was copasetic until last night.

Could not start the truck at all, wouldn't even crank. I checked fuses, used fob on button etc. finally i decided to get a jump start, boom turned over.

To be on the safe side, I first figured I needed to replace both batteries. (yes there are many trouble shooting steps to determine if it is main or aux battery)

With the way I run my system, have TAZER and do not use ESS (not recommended for magnuson superchargers), I have no real need for the aux battery, so here is what i did today:

1) Purchased Optima yellow top H6 group size, 800 CCA, 1000 CA, 140 min reserve capacity deep cycle battery

2) Removed OEM battery, fuse plate, connectors and bucket to access the aux battery (did not go through wheel well as i needed full access to the aux battery cables)

3) completely removed aux grounding cable, cut end connector by main battery to have all other posts for primary battery and IBS

4) Routed aux power wire up and behind main battery power wire, clipped bent ends on terminal plate of aux power wire and connected to main power wire on the 7mm post.

5) Removed fuse 42, reinstalled aux cover, fuse box, connectors and fuse plate, closed.

6) Installed new battery, connected pwr and ground. (power cable now includes the aux power cable, completely removed aux ground wire)

Truck runs just fine, no faults constant 14.4 volts. ESS permanently in off position due to TAZER (again because i am running a supercharger and it is highly recommended not to use ESS with that)

 

[tysongladiator]

You've gotten a lot of good advice from others, so there's not much more that I can add to that. But I do just want to say that if your dealership didn't change both the Main and Aux at the same time, they're wrong!

And also, I'm gonna attach a pic because I saw a few posts referencing the different battery and their sizes. It has the two battery sizes and the three alternator sizes and part numbers. Just in case anyone wants to check their equipment and know what they have or purchase a different brand of battery.

 

[ShadowsPapa]

You've gotten a lot of good advice from others, so there's not much more that I can add to that. But I do just want to say that if your dealership didn't change both the Main and Aux at the same time, they're wrong!

And also, I'm gonna attach a pic because I saw a few posts referencing the different battery and their sizes. It has the two battery sizes and the three alternator sizes and part numbers. Just in case anyone wants to check their equipment and know what they have or purchase a different brand of battery.

That looks like the base battery, no aux switches, etc.

With the aux switches, this is what I have (listed under optional equipment) -

Without the aux switches, this is what an identical Gladiator gets -

A JLU with the "towing and HD electric package" (includes aux switches, and is the only way to get them on the JL)

You can tell the difference by checking the fit of the battery in the tray.
With the 650 amp battery, there will be space between the front end of the battery and the tray. With the 700 the battery will fill the tray front to rear (length of the battery and tray)

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