3.6L ESS Battery Diagram

[TrickyO]

On the RHD the Washer water bottle is below the PDC. Crawling under I think the Aux battery is immediately below the main battery. Will be pulling that out to see if I can get to it. If so they have built the RHD with much easier access. Will update after I try.

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[correfe]

By all means if you can do nothing else, unplugging the relay may help, but there is a very limited set of circumstances where just unplugging the relay will improve the situation. If the Aux battery is drained, so is the Main battery because they are connected in parallel. Unplugging the relay will have limited benefit here unless you also disconnect the Aux battery negative, then you only have to charge the Main battery to get going. If just the Aux battery is drained, it means the ESS relay is bad or the ESS fuse is blown, isolating the batteries and preventing just the Aux battery from charging. Unplugging the relay won't help here.

It will help the situation where a bad Aux battery is causing sporadic electronic behavior, as long as the Main battery still has a charge. Even then, disconnecting the Aux battery negative removes any possibility of it impacting starting from the Main battery.

So if you're reading this post and learning about disconnecting the relay to increase your odds of surviving a battery issue, realize that having an adjustable wrench or a pair of pliers in the jeep to disconnect the Aux battery negative increases the odds even more. Or replace the Aux battery negative cable nut with a wing nut, so no tools are needed to disconnect it. And no need to tape or secure the battery ground.

Which one is the fuse for ESS and relay for ESS?

 

[Candsevo7]

@Jebiruph or anyone else who has experience , I was wondering if you might be able to shed some light on a problem with the jumper. My wife has a 2018 jLUR export diesel , battery went flat last year and again a few months ago and it wouldn't start , went in to jeep who said there's no issue, however it wouldn't last more than a few days . it happened again late week and like everyone else struggled to get it going , but after an hour on the charger it was fine.


when I got some time I decided to investigate further and drop test the batteries, the aux appeared ok but the main didn't respond too well and showed it was weak, we got a new odyssey ( I have had one in my jk for years and ran multiple odysseys in a few cars I had huge audio systems in )

I left the aux battery in there and disconnected the aux neg connection from the main battery terminal , made a decent jumper and fitted a 30 amp fuse.

all good for a day then during a drive the fuse blew, replaced it with a 60 amp which was ok for a week , then it also blew, both times it was cold here so lights, heated seats, wheel, screen defrost and heater were all on. assumed it was just blowing due to the load at the time . and was tempted to just make a solid link,
As I still had tons of audio stuff kicking about I made a loom with 0 gauge cable and a 150a circuit breaker as the jumper, thinking it should never go.

sadly today a few weeks on the breaker tripped. I'm struggling to understand how. as it must be way over the rating of the items it powers. unless there's a dead short on one of the aux cables which I looked and continuity tested down to earth but couldn't find any damage ,



Any ideas what I may be able to do ?

 

[Jebiruph]

@Jebiruph or anyone else who has experience , I was wondering if you might be able to shed some light on a problem with the jumper. My wife has a 2018 jLUR export diesel , battery went flat last year and again a few months ago and it wouldn't start , went in to jeep who said there's no issue, however it wouldn't last more than a few days . it happened again late week and like everyone else struggled to get it going , but after an hour on the charger it was fine.


when I got some time I decided to investigate further and drop test the batteries, the aux appeared ok but the main didn't respond too well and showed it was weak, we got a new odyssey ( I have had one in my jk for years and ran multiple odysseys in a few cars I had huge audio systems in )

I left the aux battery in there and disconnected the aux neg connection from the main battery terminal , made a decent jumper and fitted a 30 amp fuse.

all good for a day then during a drive the fuse blew, replaced it with a 60 amp which was ok for a week , then it also blew, both times it was cold here so lights, heated seats, wheel, screen defrost and heater were all on. assumed it was just blowing due to the load at the time . and was tempted to just make a solid link,
As I still had tons of audio stuff kicking about I made a loom with 0 gauge cable and a 150a circuit breaker as the jumper, thinking it should never go.

sadly today a few weeks on the breaker tripped. I'm struggling to understand how. as it must be way over the rating of the items it powers. unless there's a dead short on one of the aux cables which I looked and continuity tested down to earth but couldn't find any damage ,



Any ideas what I may be able to do ?

All the interior electronics are normally fed through the 150a N3 fuse, so 150a should be sufficient. I suspect your 150a N3 fuse is blown and either your circuit breaker is tripping at too of current or something is drawing too much current.

I copied the following from a reply in another thread, it applies here.
When installing the jumper as suggested, it works in parallel with the big battery cables and does not replace them. With the jumper installed and the only other modification being disconnecting the aux battery ground cable, the factory battery cables from the main battery positive to N3 (through N3 fuse) to the power control relay to the aux battery positive to N1 are still in place. So the power is split between the jumper and the existing battery cables.

Circumstances that cause the jumper to carry the full load are during the cold start aux battery test and when the N3 fuse is blown. The aux battery test doesn't use enough power to be a problem, but when running with a blown N3 fuse, interior accessories like the heater blower, audio system, USB ports, etc, could combine to over power the jumper.

 

[Candsevo7]

thanks so much for the response , its pretty much what I figured, ill check the n3 fuse , one question tho, why do we need a fuse in the jumper? with the aux battery in there the original cable isn't fused ?

 

[Jebiruph]

thanks so much for the response , its pretty much what I figured, ill check the n3 fuse , one question tho, why do we need a fuse in the jumper? with the aux battery in there the original cable isn't fused ?

The aux battery connects to the alternator/main battery through the 150a N3 fuse. The jumper also connects the aux battery to the alternator/main battery and also needs fused.

 

[Candsevo7]

ok so an update , ive removed the high power fuses and N3 is indeed blown . so that makes sense why the link trips with the 150 amp breaker .
now the hard part will be finding the high power fuses in the uk , jeep here are terrible with people here often waiting for months for the simplest parts .
thanks again , your help is much appreciated.

 

[Jebiruph]

ok so an update , ive removed the high power fuses and N3 is indeed blown . so that makes sense why the link trips with the 150 amp breaker .
now the hard part will be finding the high power fuses in the uk , jeep here are terrible with people here often waiting for months for the simplest parts .
thanks again , your help is much appreciated.

You should be able to move the wire from the N3 terminal to the N4 terminal and run off of that 150a fuse, there's usually nothing connected to the N4 terminal.

 

[Candsevo7]

@Jebiruph so can't get one for a week !! great service by jeep in the uk .

so as I basically have zero volts on the n3 terminal due to the blown fuse and the jumper is connected fro n1 to n2 I am bypassing the pcr and terminals on the aux battery wiring from n1 to n3 .
if I was to use an inline fuse from the batt + via a 150A fuse ( car audio kit I have) and connect that to the N3 terminal as well as the n3 wiring it should be the same as having a 150a fused supply at N3 .
the load is then shared with the breaker and fuse .

or I just use it as it was and don't have the heated seats etc turned on until my replacement fuse turns up ?

thoughts ?

 

[MMcClain]

Read the entire feed, still need some advice: 2019 JLUR 3.6 non-etq. Issue started with needing to jump battery to crank. Replaced AUX battery. Soon after, main needed to be replaced, so I upgraded to Genesis dual battery, used Optima red top (I know...). Still developed same issue needing to be jumped. Replaced IBS, no change. Replaced Zbar fuse array, no change. Replaced PCR, no change. My alternator is and has been putting out a constant voltage that will be different with each crank. However, whatever voltage is starts putting out (14.2, 13.8, etc.), it will remain constant throughout my 40 minute drive to/from work each day. I'm out of ideas based on this and other threads. Other aftermarket electronics installed are: JL Tazer (been on the Jeep for almost 3 years and 30K miles), RSE step sliders (not a new install), winch (not a new install). All else is stock as far as electronics goes. I'm sure there is a guru here that may point me to my next step. Thanks in advance.

Mike

 

[Jebiruph]

Read the entire feed, still need some advice: 2019 JLUR 3.6 non-etq. Issue started with needing to jump battery to crank. Replaced AUX battery. Soon after, main needed to be replaced, so I upgraded to Genesis dual battery, used Optima red top (I know...). Still developed same issue needing to be jumped. Replaced IBS, no change. Replaced Zbar fuse array, no change. Replaced PCR, no change. My alternator is and has been putting out a constant voltage that will be different with each crank. However, whatever voltage is starts putting out (14.2, 13.8, etc.), it will remain constant throughout my 40 minute drive to/from work each day. I'm out of ideas based on this and other threads. Other aftermarket electronics installed are: JL Tazer (been on the Jeep for almost 3 years and 30K miles), RSE step sliders (not a new install), winch (not a new install). All else is stock as far as electronics goes. I'm sure there is a guru here that may point me to my next step. Thanks in advance.

Mike

The Genesis dual battery system is supposed to protect the main battery from draining down and needing jumped.
I would reach out to them for help.

 

[MMcClain]

The Genesis dual battery system is supposed to protect the main battery from draining down and needing jumped.
I would reach out to them for help.

I reached out to them, problem is the system is meant (and does) to disconnect the AUX (forward) battery from the main to protect the main. However, the main battery is the one getting drained and keeping the Jeep from cranking. The Genesis system is working as advertised, unless I’ve missed something…

 

[Jebiruph]

I reached out to them, problem is the system is meant (and does) to disconnect the AUX (forward) battery from the main to protect the main. However, the main battery is the one getting drained and keeping the Jeep from cranking. The Genesis system is working as advertised, unless I’ve missed something…

There are a few threads that deal with the batteries draining, those threads might be helpful. It seems a common problem is the radio staying fully powered up and not going to sleep, which can run the batteries down.

 

[MMcClain]

There are a few threads that deal with the batteries draining, those threads might be helpful. It seems a common problem is the radio staying fully powered up and not going to sleep, which can run the batteries down.

Could absolutely be an issue of cycling… it is very intermittent…. Let me find those threads, thanks. Never have liked the uConnect units.

 

[OldGuyNewJeep]

Could absolutely be an issue of cycling… it is very intermittent…. Let me find those threads, thanks. Never have liked the uConnect units.

If you have the 8.4, make sure you are on latest software (39.6). There’s a thread with link to download. Known to fix parasitic drain.

As a quick test, just pull fuse F97 for a few days.

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