3.6L ESS Battery Diagram

[W1ck3d]

So, my question is... where is this power control relay?

I have pulled a few of the high power relays in the fuse block and was not able to separate the batteries. My thought is to replace this relay with a charging diode. This way, if something drains the main battery dead, then the aux won't be dragged right along with it. It makes no sense to have both batteries tied together 99% of the time, because they will both die together too. Trust me, it's happened to me once all ready when the radio didn't power down over a weekend.

Its under the battery try on the firewall... Take off the rt ft flare you cant miss it

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[TheGuyYouKnow]

... I tried connecting a couple volt meters to monitor when the batteries are connected and when they are not, but the ESS would not operate with the volt meters connected.[/QUOTE]
When you connected your voltmeters and the ESS wouldn’t operate, did it show the red ESS light on the dash?

 

[Jebiruph]

... I tried connecting a couple volt meters to monitor when the batteries are connected and when they are not, but the ESS would not operate with the volt meters connected.

When you connected your voltmeters and the ESS wouldn’t operate, did it show the red ESS light on the dash?

No error indication, just stop/start not ready. But now I see that it has to move forward at a speed greater than 5 mph for stop/start to be enabled, that was the problem. I'll have to try again.

 

[Jebiruph]

It makes no sense to have both batteries tied together 99% of the time, because they will both die together too. Trust me, it's happened to me once all ready when the radio didn't power down over a weekend.

I totally missed the tail end of your post regarding the radio not powering down causing the batteries to die. Do you know why the radio didn't power down?

I don't think this ESS is designed to be a true dual battery system. It looks like it wants to act like a single battery system except when auto stopped, then the battery duties are split. So, with the engine off and acting as a single battery, if there is a load on the system like the radio, lights or anything else, then both batteries are drained. Just like the battery would get drained on a single battery system. The Cherokee ESS runs off of a single battery, maybe this new dual battery design solves issues that the single battery system has. I would expect however, that if a battery goes bad, that the battery management would not let the bad battery drain the other battery.

 

[Arrowhead]

I totally missed the tail end of your post regarding the radio not powering down causing the batteries to die. Do you know why the radio didn't power down?

I don't think this ESS is designed to be a true dual battery system. It looks like it wants to act like a single battery system except when auto stopped, then the battery duties are split. So, with the engine off and acting as a single battery, if there is a load on the system like the radio, lights or anything else, then both batteries are drained. Just like the battery would get drained on a single battery system. The Cherokee ESS runs off of a single battery, maybe this new dual battery design solves issues that the single battery system has. I would expect however, that if a battery goes bad, that the battery management would not let the bad battery drain the other battery.

I haven't looked into this too much, but what your saying makes sense. The drop in voltage from a start event can effect all the the other systems in the vehicle. So your theory makes sense that they are divorcing the two batteries only under a ESS event so the start up will seem seamless. But under normal operation they are reconnected so they both remain charged. I guess what threw me off was the switching relay for the ESS battery was normally open, but it's hard to tell where it's connected without a full diagram to look at.

Thinking back, I test drove mine when it was fresh off the truck still in transport mode. Most of the interior accessories didn't work, but it started and ran fine. So I wonder if the ESS battery is disconnected for shipping.

 

[Rhinebeck01]

snip:

Thinking back, I test drove mine when it was fresh off the truck still in transport mode. Most of the interior accessories didn't work, but it started and ran fine. So I wonder if the ESS battery is disconnected for shipping.

@Arrowhead

JL's are shipped from the factory with the vehicles in "Ship Mode".

Ship Mode disables lots of electrical on the JL. Ship Mode is turned off when the PDI is done at the dealership.

Trivia: Ship Mode can only be turned on if the JL has under 300 miles on it. I actually toggled mine on and off just to see if I could. Again, 300 miles is max mileage as more then that Ship Mode cannot be enabled.

I thought it would be great to place the JL in Ship Mode while flat towing and also if the JL was in prolonged storage, but unfortunately, the 300 mile thing kills that idea.

Note: If anybody says the Jeep Informant did a YouTube Video on Ship Mode, they are correct. The video was pulled by him soon after I notified the Jeep Informant that his Ship Mode video was a bust because of the 300 mile thing.

.

 

[BosRacing]

Can any of you electrical gurus tell how to wire in a "master kill switch"? I am building a JL to compete in sanctioned events and one of the requirements is to have a master kill switch wired in to kill power in case of an emergency. Must be 1 switch used to kill main battery power to fuel pump and ignition system....in other words, engine must not be able to start or run with this switch in the off position.

Thanks, Bill

 

[Rhinebeck01]

@BosRacing

Can point you to how to kill all power to the JL.
https://www.jlwranglerforums.com/forum/threads/to-kill-12v-power-to-the-jl-jlu.6244/

There are 2 batteries. Main and an ESS/Auxiliary. The ESS/Auxilary is what starts the JL. Even if Main battery is disconnected the JL will still start.

 

[BosRacing]

@BosRacing

Can point you to how to kill all power to the JL.
https://www.jlwranglerforums.com/forum/threads/to-kill-12v-power-to-the-jl-jlu.6244/

There are 2 batteries. Main and an ESS/Auxiliary. The ESS/Auxilary is what starts the JL. Even if Main battery is disconnected the JL will still start.

I appreciate the response.... Already read that thread but it doesn't really tell me how to accomplish what I need with 1 switch. I am hoping someone here can figure it out and let me know.

Thanks, Bill

 

[Jebiruph]

I appreciate the response.... Already read that thread but it doesn't really tell me how to accomplish what I need with 1 switch. I am hoping someone here can figure it out and let me know.

Thanks, Bill

I don't know if it's technically correct to put the kill switch on the ground cable, but both batteries are grounded through the same cable that runs from the main battery to the body. I have tested this, but you'll want to very it yourself. If you have to disconnect the positive side, that's 4 connections. https://www.genesisoffroad.com works with the wrangler battery system, you might want to check with them or similar companies.

 

[Jebiruph]

Version 2

Here's an update to the original drawing. All the electrical connections are the same, but I've added a little more detail and some explanations with my understanding of why and how some things are behaving the way they do. I'll be adding it to the first post also.

 

[Jebiruph]

It seems the aux battery powers the power control relay, so that doesn't work. I would expect N1 and ground to work, but I'm not aware of anyone testing it yet.

From #21 regarding jump starting a JL through N1 and ground instead of the Main battery terminals. Be aware that when you jump start this way, you are going through the 150 amp PCR (ESS) Fuse. This can work, but the amps needed to crank the starter can vary based on current conditions, like outside temperature. The colder the engine, the more amps required. And lower source (jump) voltage may also cause an increase in the amps needed to crank the starter.

I have no idea how close this can get to 150 amp limit of the fuse.

 

[NathanG]

I don’t think it actually draws many amps thru N1. Just supply’s voltage to the security system/ pcm and allows car to start. I used this method to get home on a 8 hour road trip after having ess/ battery problems. I had to jump it using a booster pack on n1 and ground.

 

[Jebiruph]

I don’t think it actually draws many amps thru N1. Just supply’s voltage to the security system/ pcm and allows car to start. I used this method to get home on a 8 hour road trip after having ess/ battery problems. I had to jump it using a booster pack on n1 and ground.

I'm glad to hear the booster pack to N1 got you home, do you know what the problem with the Aux battery was? The amps drawn would depend how much charge was left in the Main battery. It sounds yours was good if it was just your Aux battery causing problems. My concern about jump starting through N1 is when them Main battery is completely dead and all the starting power goes through N1- PCR-PCR (ESS) fuse - N2 - Main battery terminal - starter. If it ever gets cold enough that it takes more than 150 amps to crank the starter, you will blow the fuse.

 

[NathanG]

My main battery was at 12.5 volts when it wouldn't start. I am not sure what the aux bat was at. I believe the problem was caused right before this happened I was running my ARB air compressor with the car off, and starting it while the compressor was running. I didn't have the compressor on for more than fifteen seconds, but maybe the extra current draw damaged the ess batt in some way. I have my ess permanently disabled by unplugging the switch..

I am also having a more recent issue with the surging at idle with the AC on full. The car idle surges up and down once a second at stoplights with the AC on full on warm days. I took it in and they found fault codes for the ESS. They replaced the battery but it didint fix anything as far as the surging. I am wondering if the codes were stored from the incident from a few months ago.

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