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Heading to Moab Wednesday and Jeep will not crank!! Need Input!

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Sprint7

Sprint7

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Have you checked the high amp N1-N8 fuses?
I put a meter on top of each of the N1-N8 lugs. With the main battery removed but the aux battery in place they each read approx .6volts
With the main battery installed they were 12.6v each.
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Mike,

Whether or not you're a big Electronic Stop Start fan, the design and implementation of ESS has really complicated the JL ignition system. The most obvious first step is checking the charge on the AUX (smaller) battery. The AUX battery must be of sufficient charge to enable a pre-start relay. This pre-start relay does not engage the starter motor directly but rather closes a secondary circuit which allows the main battery to then engage the starter. It sounds like you're missing this first circuit step.

Are their any hints on the cluster?

Have you tried jump starting? If so, did you leave the jumper cables connected for many minutes before attempting to crank? Recall, these two batteries are connected in parallel. The Main will likely take most of the charging energy up-front, but it's the AUX battery that must be charged in order for the Jeep to start. This will require some charging time.

Lastly, double check all the connections and make sure all the fuse and relays are pushed firmly down and that they make good connections within the fuse and relay module. This is the most likely culprit because you have to move this module out of the way just to gain access to the AUX battery.

Don't panic. Everything was working. It's just now a matter of ensuring everything has been put back together and has sufficient charge on the new batteries. New batteries are not always received fully charged.

You'll get there...

Jay
I just went through everything again. checked the aux battery and it is connected properly and it read 12.63 volts. Checked the module and didn’t see any bent / broken pins. Reinstalled and everything went together smoothly So it seemed.

Dome lights, horn work, dash and 8.2 screen energizes, but doesn’t fully function. See picture.

I also checked that each relay was pushed down all the way and have checked every fuse.

I have had a dead battery in the jeep a few times in the last month playing with the ARB, etc (hence the new batteries) and the dash would light up and act weird. Starter would “click”, etc. It will not do anything. It is like the aux battery is powering up some things but installing the new main battery has not effect. I have a charger on it now and will check in it 20 mins. May even put the old battery back in just to check.

I am truly at a loss.
 
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I also just pulled and replaced each relay one at a time with no effect.

What would possibly keep the main 12v battery from powering up the Jeep??????

I also have a charger on the main battery with no effect
 

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Mike,

The previous dead battery is your hint. Something recently has been introduced which is drawing current with the ignition off. Because both batteries are (almost always) connected in parallel, they are both being discharged simultaneously.

Since the AUX battery is physically smaller and can only store a smaller amount of the overall energy, it will likely be the first to be depleted. However, there are a lot of dynamics involved when different sized voltage sources are connected together, whether in series or parallel. Such as coss-charging, parasitic loading, etc.

Your overall goal will need to determine why your batteries are being drained to begin with. The problem you're facing now will be repeated until you solve root cause.

Have you placed either a switch or relay between power and your new ARB compressor? I'd start there. Or at least disconnect it completely until you've puzzled all this other stuff out first.

I know, call me Captain Obvious.

Charging (and changing) batteries routinely would not be on my list of fun things to do with my Jeep.

Jay
 
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I had a dead battery a few times because of the ARB fridge that was left on and also I was leaving the FOB in the Jeep. It is not a daily driver and may sit for up to two weeks. I literally cranked the Jeep and backed in the garage. Changed the batteries and now nothing
 

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I had a dead battery a few times because of the ARB fridge that was left on and also I was leaving the FOB in the Jeep. It is not a daily driver and may sit for up to two weeks. I literally cranked the Jeep and backed in the garage. Changed the batteries and now nothing
OK, one more captain obvious question and I apologize up-front for it being so stupid (I'm embarrassed); the fridge isn't running while you're not using the Jeep is it? Do you ever forget to turn it off? Fridge applications tend to want their own power source independent of the vehicle (i.e. it's own battery).

How confident are you that the old batteries are bad and the new batteries are indeed good? Have they been recently load tested?

Do you have a battery tender (something more comprehensive than a simple charger)? Properly charging (effectively managing) batteries is a truly complicated science especially when multiple dissimilar batteries are connected together. You can generally get by at throwing sufficient energy at them for some arbitrary amount of time, but they can be damaged or degraded through improper charging cycles, especially when repeatedly recharged casually (improperly) over time.

Are either or both of these conditions possible?

Sorry to say this but the JL has not been designed to what you're trying to do with it. Have you (or can you) consider third-party power source providers like a Genesis Dual Battery kit?
 
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Yes the fridge is wired to the main battery and has been for almost a year and I have left if on in low power shutoff a few times which has run the battery down until the Jeep will not crank. The Jeep is not acting like it is low battery. It is acting as if the main 12v battery is not connected even though it is.
 

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Yes the fridge is wired to the main battery and has been for almost a year and I have left if on in low power shutoff a few times which has run the battery down until the Jeep will not crank. The Jeep is not acting like it is low battery. It is acting as if the main 12v battery is not connected even though it is.

How about you take 10 pics and post them here so maybe the rest if us might spot something.
 
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Jeep Wrangler JL Heading to Moab Wednesday and Jeep will not crank!!  Need Input! 024C9A43-5591-4FCB-8F98-67819B896A54
Jeep Wrangler JL Heading to Moab Wednesday and Jeep will not crank!!  Need Input! 2D5B12DC-D8E0-4F81-A58B-B8948B63627C
Jeep Wrangler JL Heading to Moab Wednesday and Jeep will not crank!!  Need Input! D5913824-76ED-444D-BBDF-7344C84EDA0F


The photo above circled in red is the main fuse bar for the N1-N8. I swapped it on another JL and his fired right up and mine still dead.

Next i am going to swap the old batteries back in and then swap the module with the other JL.

Anything you see please let me know. I really hope it is something that I am just missing.



Jeep Wrangler JL Heading to Moab Wednesday and Jeep will not crank!!  Need Input! E707D028-595F-4B9E-99E4-C5F7F80160BC
 

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I can't tell from the angle of this picture but there is a battery sensor directly under the top strap in your picture. Is it plugged in?
 
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It is plugged in. I even swapped them from the other JL with no luck.
 

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It is plugged in. I even swapped them from the other JL with no luck.
I'm really stuck. I'm voting for the original batteries just to see what's up. I haven't removed my batteries but every year I've had before had a sensor under the battery to monitor temp. Did you see anything like that when making the change?
 

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I would try to reset the electronics by separating and removing these grounds, let it sit for 10 minutes before hooking them back up.

Jeep Wrangler JL Heading to Moab Wednesday and Jeep will not crank!!  Need Input! 2D5B12DC-D8E0-4F81-A58B-B8948B63627C


I have had success with issues like this on another make of vehicle. It seems something snagged up when the control unit got it's power back. Like a re-boot of the system.



It's worth a shot.
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