To Kill 12v Power to the JL/JLU

FatBoy01

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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





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mgroeger

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What page in the manual is this?
 
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What page in the manual is this?
This info is not in the manual. 1st pic is one I doctored up. The second pic is from JL install instr. for the Aux kit I believe.
I promise ...;) this is the way you kill all 12v power to the JL/JLU.
 

mgroeger

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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.
 

JeepDrvr2018

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Well that is something, don't thin my 2013 JK Sahara has all those. Is the battery under the battery the one for start/stop?
 

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Yes, my understanding is it's the start/stop battery although it may control other things as well.

I'm not sure about the JKs, this info above in the pic is only for the JLs. People were just disconnecting the battery when they were doing electrical work like adding switches, lights, etc... not realizing they had not truly killed the power to the car.
 

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Well this was interesting. Last night I took the three ground terminals off and it did indeed kill everything in the Jeep. The lead that goes to the fender that is connected to the 10mm bolt seems to be "live". By that I mean when reconnecting it the thing sparked and I could here a relay or something clicking in the fuse box next to it.

Other than that everything powered back up and all presets on radio were still there.
 

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Oh... and it didn't fix the compass :(
 

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Thanx FatBoy01--very good info --

JIMBO
 

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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
Twice I've had to disconnect the three negative battery terminals. Each time terminal #2 (from your pic) sparks like heck when you touch it back to the bolt to thread it on. I can here a clicking noise coming from the black box right next to it.
Have you experienced that?
 
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FatBoy01

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@mgroeger

I do not have a JL yet.

Normal to see this ....... is what I can tell per posts here, a YouTube video I saw and a tech I asked at the stealership a couple of weeks ago.
 

mgroeger

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OK, thanks for letting me know. If you have the link to the video I'd like to see it. I figured it had to be normal even though I'd never seen a negative terminal do that before.

"Stealership"... LOL
 
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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


 
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FireWire

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interesting stuff regarding the JL electrical system. In the firefighting world, it has been common practice to disconnect the battery in the case of a vehicle crash. This is to prevent an air bag going off while a patient is being attended to and to prevent cutting into live wires. Hybrids are a whole different animal to deal with. Now ESS cars are added to the mix. I will be doing some research on procedures for dealing with these vehicles. Especially because we have one.
 

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Speaking of research & manuals, does anyone know where to obtain a Jeep shop manual for the JL?
 

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