- Thread starter
- Banned
- #1
Special thanks to @Jebiruph, whose foundations he's made on this subject matter bring me here. I'm sorry this is long winded--especially for those largely in the know. Explaining things clearly often trades off with brevity.
I'm going to use one of his quotes:
(Disclaimer: Theories regarding the 3.6L ESS starting process are educated guesses, here's mine.)
~~~~~~~~~~
This information does not apply to the 2.0L JL. It's electrical system varies from the 3.6L's
~~~~~~~~~~
A scenario: you've come to your 3.6L JL and pressed the unlock button on your working fob... or maybe you've touched the handle of your proximity sensor driver's door with your working fob nearby and nothing happens.
Fortunately, you have a physical key, which gets you inside the Wrangler and out of the elements all while no alarm sounds because your 3.6L has no power.
Or maybe you have a Sport and just turned the physical key to get inside, attempted to start your 3.6L and nothing happens.
The reason why the battery/batteries died...? Who knows. My focus is on getting you going, to dealer service or first home, and maybe with a just a booster pack, and maybe faster.
~~~~~~~~~~~~~~
So you hook up that booster pack you bought, which just for argument's sake is fresh and a really strong one. You connect it to the terminals of the main battery as per the manual and quickly try to crank. Nothing happens, as has been that reported on the forum for those who've tried.
You then realize (or maybe already knew) that the manual says to wait a while when doing such jumps starts from a donor vehicle, and you give that wait a try (as a second attempt or initially) with your booster pack and then try to crank. Nothing happens—only it's for different reasons—again just like that reported on the forum.
~~~~~~~~~~~~~~
Now, it's entirely possible that there are problems with your rig beyond dead batteries that no jump start is going to (alone) cure. It's possible it's just your batteries that are dead, but your booster pack lacks adequate charge.
The point is, if it's just dead batteries, each crank likely failed for different reasons that it's important to understand if you want to increase your chances that you *might* be able to crank from a booster pack.
And there are boosters out there that lack adequate charge no matter what, to crank your 3.6L JL, but others that have enough power might have failed JL owners based on some electrical facts discussed below about the 3.6L.
~~~~~~~~~~~~~~
Your 3.6L JL has two batteries, the main, and the ESS/Aux smaller one. That smaller one is primarily tasked with running all your electrical needs during ESS events. Almost all the time these two batteries are connected in parallel (positive to positive, negative to negative): which increases amperage while keeping voltage constant. In fact the only time these batteries are separated is during an ESS event, and an instant before the engine is cranked: be that crank at the end of an ESS event, or when you press the brake and push the start button (i.e. a "cold" crank.)
And it is during that instant, that the ESS/Aux battery is tasked, all on its own, with telling the starter to crank the engine. The actually energy to effect this work of the starter comes from both/either batteries, as just prior to the starter turning, the 3.6L reconnects the two batteries in parallel.***
I should qualify that statement. Based on some testing Jerry did, what can definitively be said is that the ESS/Aux battery must have power to crank your 3.6L. Whether that's because the ESS/Aux battery tells the starter all on its own to turn, or because the 3.6L first tests the ESS/Aux battery for power, and won't proceed to attempt a crank if it doesn't, still remains unclear. The point is the prior paragraph should be thought of conceptually, as in what "appears" to happen if not actually what does happen or the exact explanation of the rig's observed behaviors. I'll note that with *** .
The implication of this is that the ESS/Aux battery must have some basic level of power all on its for you to start your 3.6L. You could have swapped your main battery for 12V cables coming off a nuclear power plant: if that ESS/Aux battery is dead (and those cables haven't been given time to charge the ESS/Aux battery or can't because the ESS/Aux battery is defective,) you're not cranking or going anywhere.
@Jebiruph's N1-N2 jumper workaround of other posts addresses this by insuring the batteries always remain connected in parallel, but comes with its own caveats IMHO, specifically that I'd be inclined to turn ESS off if using it. (Some of you may consider that a feature!)
The reason why I feel this way is that ESS won't engage or remain in ESS mode IF engaged, if the ESS battery lacks adequate power to enter ESS, or loses enough power during the ESS event in the process of solely energizing your 3.6JL's appliances.
With the batteries connected together all the time with Jerry's jumper, both batteries can be taxed during an ESS event, the ESS event can happen when it normally wouldn't be allowed by the 3.6L to occur because the ESS/Aux battery alone lacks the power (but the 3.6L doesn't see this because it's connected to the main battery at all times by Jerry's jumper,) and/or ESS could remain on longer than it should at a red light because the main battery is helping to power the ESS event, than were it isolated from the ESS/Aux battery during the event as per factory spec. In such cases the JL would have sensed a depleting ESS/Aux battery during the ESS event and terminated the ESS event early, so the ESS/Aux battery still has enough power to tell the starter to engage.
This could rob the main battery of power it needs to crank the engine: a process it bears most of the work of along with the ESS/Aux battery. In fact the role of the ESS/Aux battery is to let the main battery sit idle during an ESS event so it has adequate charge to crank the engine (along with the ESS/Aux battery.)
This is NOT a stab at Jerry's brilliant solution but rather an indication for its usage. By analogy, just as some life saving medicines have contraindications (e.g. some can't be taken with grapefruit juice,) Jerry's hack might best not be run with ESS able to engage. This is not to diminish the hack's worth.
~~~~~~~
In the second situation with your dead 3.6L JL you've waited for a while with the booster connected to the main battery. Because both batteries are connected in parallel with the 3.6L at rest, some of that booster's power went to charge the ESS/Aux battery (and the main battery too) but in so doing, you may have robbed the booster of adequate power to crank the engine--much as giving the ESS/Aux battery (if not your main one) a basic charge is no less essential to turning over your engine than an adequately powered booster: the why's of which discussed above.
You are wasting what little power your booster has on charging the main battery. A fully charged ESS/Aux battery, or one connected in parallel to a strong enough booster may have the energy to tell the starter to crank, and then actually turn the starter.
This is because while the ESS/Aux battery solely tells the starter to fire***, and the 3.6L JL connects both batteries in parallel just before this happens*** , and you can (fact) crank your 3.6L on the ESS/Aux battery alone if that battery is adequately charged, but not the main battery alone. The main battery will not signal the starter*** (that's solely the ESS/Aux battery's job***) unless you've hooked up Jerry's N1-N2 jumper.
(Again this is conceptual. It's the behavior we see, whose causes and events are not 100% clear.)
~~~~~~~~~~
@Jebiruph has addressed this wasted charge on the main battery from the booster. He has shown us how disconnecting all the cables to the main battery's negative post, and hooking them up to the negative lead of the booster pack, while connecting the positive lead of the booster pack to the positive post of the main battery gets the booster pack to solely charge the ESS/Aux battery. But this approach may require the booster to charge the ESS/Aux battery somewhat (depleting some of the booster's strength).....
https://www.jlwranglerforums.com/fo...y-consolidated-information.25377/#post-602294
because at crank, that ESS/Aux battery may be isolated from the booster for an instant, just like it is the main battery in factory operation.
And while that basic charge to the ESS/Aux battery is necessary because once you attempt that crank, the 3.6L is going to isolate the ESS/Aux battery from all else, including your booster***.
Or maybe there's another approach.
What may be both faster and possibly more likely to work (because it is faster, allowing the booster pack to be depleted less before a cold crank is attempted) is as follows. I have not tried it. It could be wrong, but it is based on the 3.6L electrical schematics.
https://www.jlwranglerforums.com/forum/threads/3-6l-ess-cold-start.28297/
In the Power Distribution Center (PDC), located under the hood close to the fire wall on the passenger's side, when uncovered, lies a high powered fuse bar on its driver's side. I am theorizing that it may be better to connect the positive side of your booster pack to the N1 terminal, closest to the grill, than the positive post of the main battery.
(I get that it may be hard to connect solely to N1 without a properly thick and fused wire that distances your booster's positive side from it. )
Doing this may hard wire the booster pack to the ESS/Aux battery for the duration of the connection so the two batteries act as one. This might (near) immediately provide the power the ESS/Aux battery needs to continue with the crank, as seen by the 3.6L test of the ESS/Aux battery Jerry describes (conceptually notifying the starter) AND energize that starter.
This is moot with Jerry's N1-N2 jumper in place. I believe this the case because he has you connect the positive of the booster pack to the positive terminal of the battery, which is connected to N2, which is jumpered to N1--so the juice gets to N1.
But if you want to run ESS as designed, this suggests another slightly modified approach.
It may be necessary for the ESS/Aux battery to have some of its own power, but perhaps less than the waiting period that charges it and paradoxically may rob the booster of its ability to energize the load intensive starter to crank.
If this thread has me fall on my face in critiques, the point is we'll all learn.
Cheers
I'm going to use one of his quotes:
(Disclaimer: Theories regarding the 3.6L ESS starting process are educated guesses, here's mine.)
~~~~~~~~~~
This information does not apply to the 2.0L JL. It's electrical system varies from the 3.6L's
~~~~~~~~~~
A scenario: you've come to your 3.6L JL and pressed the unlock button on your working fob... or maybe you've touched the handle of your proximity sensor driver's door with your working fob nearby and nothing happens.
Fortunately, you have a physical key, which gets you inside the Wrangler and out of the elements all while no alarm sounds because your 3.6L has no power.
Or maybe you have a Sport and just turned the physical key to get inside, attempted to start your 3.6L and nothing happens.
The reason why the battery/batteries died...? Who knows. My focus is on getting you going, to dealer service or first home, and maybe with a just a booster pack, and maybe faster.
~~~~~~~~~~~~~~
So you hook up that booster pack you bought, which just for argument's sake is fresh and a really strong one. You connect it to the terminals of the main battery as per the manual and quickly try to crank. Nothing happens, as has been that reported on the forum for those who've tried.
You then realize (or maybe already knew) that the manual says to wait a while when doing such jumps starts from a donor vehicle, and you give that wait a try (as a second attempt or initially) with your booster pack and then try to crank. Nothing happens—only it's for different reasons—again just like that reported on the forum.
~~~~~~~~~~~~~~
Now, it's entirely possible that there are problems with your rig beyond dead batteries that no jump start is going to (alone) cure. It's possible it's just your batteries that are dead, but your booster pack lacks adequate charge.
The point is, if it's just dead batteries, each crank likely failed for different reasons that it's important to understand if you want to increase your chances that you *might* be able to crank from a booster pack.
And there are boosters out there that lack adequate charge no matter what, to crank your 3.6L JL, but others that have enough power might have failed JL owners based on some electrical facts discussed below about the 3.6L.
~~~~~~~~~~~~~~
Your 3.6L JL has two batteries, the main, and the ESS/Aux smaller one. That smaller one is primarily tasked with running all your electrical needs during ESS events. Almost all the time these two batteries are connected in parallel (positive to positive, negative to negative): which increases amperage while keeping voltage constant. In fact the only time these batteries are separated is during an ESS event, and an instant before the engine is cranked: be that crank at the end of an ESS event, or when you press the brake and push the start button (i.e. a "cold" crank.)
And it is during that instant, that the ESS/Aux battery is tasked, all on its own, with telling the starter to crank the engine. The actually energy to effect this work of the starter comes from both/either batteries, as just prior to the starter turning, the 3.6L reconnects the two batteries in parallel.***
I should qualify that statement. Based on some testing Jerry did, what can definitively be said is that the ESS/Aux battery must have power to crank your 3.6L. Whether that's because the ESS/Aux battery tells the starter all on its own to turn, or because the 3.6L first tests the ESS/Aux battery for power, and won't proceed to attempt a crank if it doesn't, still remains unclear. The point is the prior paragraph should be thought of conceptually, as in what "appears" to happen if not actually what does happen or the exact explanation of the rig's observed behaviors. I'll note that with *** .
The implication of this is that the ESS/Aux battery must have some basic level of power all on its for you to start your 3.6L. You could have swapped your main battery for 12V cables coming off a nuclear power plant: if that ESS/Aux battery is dead (and those cables haven't been given time to charge the ESS/Aux battery or can't because the ESS/Aux battery is defective,) you're not cranking or going anywhere.
@Jebiruph's N1-N2 jumper workaround of other posts addresses this by insuring the batteries always remain connected in parallel, but comes with its own caveats IMHO, specifically that I'd be inclined to turn ESS off if using it. (Some of you may consider that a feature!)
The reason why I feel this way is that ESS won't engage or remain in ESS mode IF engaged, if the ESS battery lacks adequate power to enter ESS, or loses enough power during the ESS event in the process of solely energizing your 3.6JL's appliances.
With the batteries connected together all the time with Jerry's jumper, both batteries can be taxed during an ESS event, the ESS event can happen when it normally wouldn't be allowed by the 3.6L to occur because the ESS/Aux battery alone lacks the power (but the 3.6L doesn't see this because it's connected to the main battery at all times by Jerry's jumper,) and/or ESS could remain on longer than it should at a red light because the main battery is helping to power the ESS event, than were it isolated from the ESS/Aux battery during the event as per factory spec. In such cases the JL would have sensed a depleting ESS/Aux battery during the ESS event and terminated the ESS event early, so the ESS/Aux battery still has enough power to tell the starter to engage.
This could rob the main battery of power it needs to crank the engine: a process it bears most of the work of along with the ESS/Aux battery. In fact the role of the ESS/Aux battery is to let the main battery sit idle during an ESS event so it has adequate charge to crank the engine (along with the ESS/Aux battery.)
This is NOT a stab at Jerry's brilliant solution but rather an indication for its usage. By analogy, just as some life saving medicines have contraindications (e.g. some can't be taken with grapefruit juice,) Jerry's hack might best not be run with ESS able to engage. This is not to diminish the hack's worth.
~~~~~~~
In the second situation with your dead 3.6L JL you've waited for a while with the booster connected to the main battery. Because both batteries are connected in parallel with the 3.6L at rest, some of that booster's power went to charge the ESS/Aux battery (and the main battery too) but in so doing, you may have robbed the booster of adequate power to crank the engine--much as giving the ESS/Aux battery (if not your main one) a basic charge is no less essential to turning over your engine than an adequately powered booster: the why's of which discussed above.
You are wasting what little power your booster has on charging the main battery. A fully charged ESS/Aux battery, or one connected in parallel to a strong enough booster may have the energy to tell the starter to crank, and then actually turn the starter.
This is because while the ESS/Aux battery solely tells the starter to fire***, and the 3.6L JL connects both batteries in parallel just before this happens*** , and you can (fact) crank your 3.6L on the ESS/Aux battery alone if that battery is adequately charged, but not the main battery alone. The main battery will not signal the starter*** (that's solely the ESS/Aux battery's job***) unless you've hooked up Jerry's N1-N2 jumper.
(Again this is conceptual. It's the behavior we see, whose causes and events are not 100% clear.)
~~~~~~~~~~
@Jebiruph has addressed this wasted charge on the main battery from the booster. He has shown us how disconnecting all the cables to the main battery's negative post, and hooking them up to the negative lead of the booster pack, while connecting the positive lead of the booster pack to the positive post of the main battery gets the booster pack to solely charge the ESS/Aux battery. But this approach may require the booster to charge the ESS/Aux battery somewhat (depleting some of the booster's strength).....
https://www.jlwranglerforums.com/fo...y-consolidated-information.25377/#post-602294
because at crank, that ESS/Aux battery may be isolated from the booster for an instant, just like it is the main battery in factory operation.
And while that basic charge to the ESS/Aux battery is necessary because once you attempt that crank, the 3.6L is going to isolate the ESS/Aux battery from all else, including your booster***.
Or maybe there's another approach.
What may be both faster and possibly more likely to work (because it is faster, allowing the booster pack to be depleted less before a cold crank is attempted) is as follows. I have not tried it. It could be wrong, but it is based on the 3.6L electrical schematics.
https://www.jlwranglerforums.com/forum/threads/3-6l-ess-cold-start.28297/
In the Power Distribution Center (PDC), located under the hood close to the fire wall on the passenger's side, when uncovered, lies a high powered fuse bar on its driver's side. I am theorizing that it may be better to connect the positive side of your booster pack to the N1 terminal, closest to the grill, than the positive post of the main battery.
(I get that it may be hard to connect solely to N1 without a properly thick and fused wire that distances your booster's positive side from it. )
Doing this may hard wire the booster pack to the ESS/Aux battery for the duration of the connection so the two batteries act as one. This might (near) immediately provide the power the ESS/Aux battery needs to continue with the crank, as seen by the 3.6L test of the ESS/Aux battery Jerry describes (conceptually notifying the starter) AND energize that starter.
This is moot with Jerry's N1-N2 jumper in place. I believe this the case because he has you connect the positive of the booster pack to the positive terminal of the battery, which is connected to N2, which is jumpered to N1--so the juice gets to N1.
But if you want to run ESS as designed, this suggests another slightly modified approach.
It may be necessary for the ESS/Aux battery to have some of its own power, but perhaps less than the waiting period that charges it and paradoxically may rob the booster of its ability to energize the load intensive starter to crank.
If this thread has me fall on my face in critiques, the point is we'll all learn.
Cheers
Sponsored
