To Kill 12v Power to the JL/JLU

RERAIL

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Additional info that you might be interested in..

You can have a fully charged Main battery and if the ESS battery is either dead or disconnected, the JL will not start, even though the main battery is fully charged. On the other hand, if the main battery is missing or dead the ESS battery can start the JL/JLU.
.

If you wanted to isolate the positive side, disconnect N1 & N2 in the power distribution box.
N1-Main battery, N-2 ESS battery.
disbox2.jpg

Is the ESS Battery a deep cycle battery? I hope the JLU can be jump started if the ESS battery goes bad.





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WXman

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OK I'm confused.

I just went outside and disconnected all 3 ground wires from the fender. I also disconnected the lug from the positive post on the main battery. And then I disconnected the the lug from the negative post on the main battery AND isolated both wires on it.

So...NOTHING was connected.

I then tested and STILL got 12.2 volts at the postive/negative wires. There was still power on the system.

WTH?
 

mgroeger

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OK I'm confused.

I just went outside and disconnected all 3 ground wires from the fender. I also disconnected the lug from the positive post on the main battery. And then I disconnected the the lug from the negative post on the main battery AND isolated both wires on it.

So...NOTHING was connected.

I then tested and STILL got 12.2 volts at the postive/negative wires. There was still power on the system.

WTH?
Was probably coming from the ESS battery. Nothing in the Jeep should have been working though, correct? That's because the ESS battery does not fee things like the radio etc...
 

Zfasha

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I believe you :)
Just was curious, there are others on the forums saying the same thing. I need to disconnect the battery tonight. Yesterday I went through a hi pressure car wash and now the compass shows -- instead of N, E, etc...
Hopefully that will fix it.
I had the compass issue and also the.carplay issue. It was a TSB at dealer to fix. There is a tread here on that issue
 

TroyBoy

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You DO want to kill 12v power before working on any electrical connections on your JL/JLU!

To kill 12v power coming from the JL/JLU's Main and ESS batteries you need to disconnect as per the picture below. One nut is a 10mm nut and the other two, are 13mm nuts.

JLpower.jpg



grounds3.JPG
@Rhinebeck01 @WranglerMan
I did some playing with this today and it turns out that you only have to disconnect #2.
 

mgroeger

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To fix the compass you will need some direction
LOL. Turns out the compass was OK. If you do ever need to calibrate the compass drive in a circle once or twice. Turn abouts work well, I'm not joking it's posted somewhere.
 

euells

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You DO want to kill 12v power before working on any electrical connections on your JL/JLU!

To kill 12v power coming from the JL/JLU's Main and ESS batteries you need to disconnect as per the picture below. One nut is a 10mm nut and the other two, are 13mm nuts.

JLpower.jpg



grounds3.JPG
I have a couple of questions....
I want to hook up a power distribution block under the dash - this will provide power to a powered sub, a trailer hitch connection, and some additional lighting. I bought an insulated block that allows a 4 Gauge input from the battery, and 4 8-10 gauge connections out. I have penetrated the firewall and have the block installed, but after seeing this diagram I am wondering if I should tap the N1 terminal so that the sub stays alive during an ESS event. Is this a valid approach? Is there also one of the three bolts on the positive terminal that would do the exact same thing?
 
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jamesj242003

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Once you disconnect all 3 negative terminals, what is the sequence to hook the negative terminals back up? Would it be, 3, 2 then 1?

Am going away for several weeks and would like to prevent both batteries from draining. Is disconnecting all 3 negative terminals the best way to prevent both batteries from draining?
 

JIMBOX

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The BEST PROTECTION for the jeep, when left alone for more than a couple weeks ---

Is a simple BATTERIY MAINTAINER-- fairly cheap and will keep the sulfirtes down and the batteries at top charge--maintain all MEDIA SETTINGS/RADIO SETTINGS--ETC-

I've been using MAINTAINERS for over 25 years--SUCCESS!!!

JIMBO
 

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Once you disconnect all 3 negative terminals, what is the sequence to hook the negative terminals back up? Would it be, 3, 2 then 1?

Am going away for several weeks and would like to prevent both batteries from draining. Is disconnecting all 3 negative terminals the best way to prevent both batteries from draining?
So what's the correct complete unhooking and re-hooking procedure for disconnecting the battery in a JL? and what order too (pls and thanks)
 

mgroeger

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So what's the correct complete unhooking and re-hooking procedure for disconnecting the battery in a JL? and what order too (pls and thanks)
If I recall correctly it doesn't matter, just get all three disconnected and then all three reconnected.
 

The_Jason

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I just disconnected all 3 negative ground points and still have power. Dome lights and radio still work. Am I missing something?
 

Redbaron73

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I too disconnected 3 grounds on the fender wall, the positive cable and the negative cable.

Most items lost power, but the rear 12v accessory was still powered.


I went back to the engine and found another lug close to the air filter box. I removed this and something started making a whining noise like the accessory mode was on. The squeal was electronic in nature, coming from the engine compartment.

I am very confused now.

I did verify that no grounds where shorting to the frame...even went so far as to wrap them.
 

N.C. Jeeper

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Good info here for sure. Sorry if I missed this but is there any specific amount of time that the three negatives need to be disconnected to reset the PCM?
 

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