New Auxiliary Battery instant drain Help!!!

[Dfwill29]

I have a 2020 Unlimited Rubicon 2.0l, and I am having crazy issues. I have both new battery’s, and I have issues where it won’t start, all lights in cluster flicker, all kinds of lights on, wipers run won’t cut off, and the push button start won’t turn off after pressed, on the fuse box I checked the N1 battery lead which is the Aux battery lead with the main battery disconnected and it goes all the way down to like 2volts or 0, it has a instant drain, and I hear a relay of some sort clicking every couple minutes, when I disconnect the N1 lead the voltage will eventually come back up to 12 volts on the Aux battery, that’s where I’m at with it at the moment, just seeing if anyone else had any crazy issues like this, or what to try

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[Fudster]

I have a 2020 Unlimited Rubicon 2.0l, and I am having crazy issues. I have both new battery’s, and I have issues where it won’t start, all lights in cluster flicker, all kinds of lights on, wipers run won’t cut off, and the push button start won’t turn off after pressed, on the fuse box I checked the N1 battery lead which is the Aux battery lead with the main battery disconnected and it goes all the way down to like 2volts or 0, it has a instant drain, and I hear a relay of some sort clicking every couple minutes, when I disconnect the N1 lead the voltage will eventually come back up to 12 volts on the Aux battery, that’s where I’m at with it at the moment, just seeing if anyone else had any crazy issues like this, or what to try

It sounds like you may have a defective albeit new ESS battery.

If I were in your shoes I'd first, with the engine off, disconnect the cable that leads from the negative terminal of the ESS battery and connects to the main battery's negative post. There are two factory cables there. One leads to the body ground on the passenger's front quarter panel. Leave that intact. It's the other cable that you should disconnect temporarily and ideally insulate its end with electric tape so as to prevent a short should the lose cable touch metal.

Next, temporarily remove Fuse 42 from the Power Distribution Center (PDC. ) The PDC is the black box closest to the passenger's seat otherwise under the hood. If you pop its cover off you can locate Fuse 42 from the chart on the back of the PDC cover that you removed.

Keep the fuse.

This fuse removal prevents energization of the relay that separates the two batteries at the two times that happens: 1) for an instant at cold crank and 2) during ESS events. You've tricked your vehicle into thinking it has two batteries connected when now only the main battery is.

During this test turn ESS off with the button on the dash. We don't want ESS engaging with only one battery.

See if this solves your problem. If it does, it points to fault with your ESS battery.

You can also test the main battery. With Fuse 42 still disconnected, reconnect that dangling cable (removing any insulation you may have put on it first) but temporarily remove all the cables from the main battery's negative post (including it.) Now your JL is running solely on the ESS battery--which it can provided the ESS battery has charge and is working correctly.

At the end of all this, again with the engine off, don't forget to reconnect all the cables to the main battery's negative post and reinsert Fuse 42.

Let us know your findings. It's possible that it is not the batteries, but, for example, one of the high amp fuses, or yet something else.

 

[Dfwill29]

Thanks for the starting point Fudster, I will check this and will let you know of my findings

 

[Dfwill29]

Ok, Fudster I ran through all the checks, removed the fuse, connected main battery with the aux battery ground off, the ESS turned off tried to crank it and it just bumps the starter, but I will say I am able to turn the ignition on and off where in the past once it was on I couldn't get it to turn off with both battery's connected, both battery's are fully charged, when I put a jump box on battery it will crank, but while it's running it acts crazy, like the electric cooling fan will turn on and off repeatedly, I have wondered if the computer is potentially bad? Unless having the ESS bypassed causes issues But it seems like whatever is on the ess circuit is shorting out, so ? your help is greatly appreciated ?

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