Jeep won’t start after brand new battery

[Grace213]

The main. From my understanding, the auxiliary battery wouldn’t prevent the vehicle from starting.

As much as you would think the aux battery would not cause a no start condition, it actually does. Was in the same boat as you until I replaced the aux battery. It is almost as bad as the TJ computer checking 5 or 6 things before allowing ignition to come on. Replace the aux and you will be good.

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[Rhinebeck01]

@gato

I inadvertently posted some misinformation earlier... Only excuse I have is daaaah, I forgot..

Anyway, do know..

...that the updated 2018 and newer JLs, the first aux battery test failure disables ESS and turns on the error light. As long as it's disabled, it will not test the aux battery and will start the first time with a bad aux battery. If the error is cleared, it goes back to testing the aux battery.

 

[Rhinebeck01]

Thank you so much for taking the time to respond. I tried to read the above thread, but there is simply so much more complex discussion.

I simply wanted to take the Aux out of the picture if it ever fails. Sounds like disconnect the negative and jump N1-N2 (not sure why it needs to be fused though).

I already carry a fully charged NOCO aux battery in all my vehicles in case main battery is dead.

I'm all for eliminating complexity out of my vehicles. I don't use ESS (Tazer disabled).

@gato

Yes, lots of info in that thread I gave a link to earlier...

I've read through that thread so many times. So much information there ... so much to remember.

Do though, if you can, read through it.
Jebiruph's info is very clear and it will sink in after awhile. 8-). The ramblings like in this thread can confuse. things.

Earlier, I should have just said as I usually do.... Go read at that thread..

Anyway, Consider going with the jumper. No way would I do as Russ suggests and have to look at an Evic message all the time. Jumper only costs a few $.

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[Mr. Curti]

Interesting post. I have a 2020 with the 3.0 and I am experiencing a very similar behavior. Now I’m curious as to if I disable the AUX battery, as previously mentioned, if my Jeep will start. Because changing the main battery did not solve the problem.

 

[entropy]

@gato

I inadvertently posted some misinformation earlier... Only excuse I have is daaaah, I forgot..

Anyway, do know..

...that the updated 2018 and newer JLs, the first aux battery test failure disables ESS and turns on the error light. As long as it's disabled, it will not test the aux battery and will start the first time with a bad aux battery. If the error is cleared, it goes back to testing the aux battery.

Yeah I had an aux battery die. This is exactly what happened. And I had a red circle show up on the dash.

Dealer installed one of them GPS anti theft devices. It drained the aux battery till it died.

I had the dealer replace the aux battery, I tried for them to also replaced the main but they said no. Then I ripped the GPS locator off the jeep. I own the jeep so it isnt an issue. If i was making payments, id technically need to leave the stupid thing on.

 

[entropy]

I don't deny your circumstances and am sorry for them. I do want to say that there's a good chance that the GPS device drained both batteries, which are connected in parallel but for an instant during normal cold cranks and ESS events.

Yes I agree. I guess this system couldnt handle the GPS being connected. My batteries were constantly charging until I remove the damn thing. Being that the small battery is well smaller, it went out first. I am going to replace them both soon myself

 

[gato]

@gato I forgot to include another side effect of @Jebiruph's jumpering. At least on the 3.6L JL, after 6 cold cranks, where the vehicle determines that the voltages of the ESS battery and the main battery are identical, I think it turns off ESS and throws up that EVIC ESS off light I mentioned.

At next crank, if I understand correctly, the EVIC light clears for another 6 cold crank cycles.

This is not some "dig" at the hack. Heck, the Genesis Offroad battery kit people love does the same thing.

Using @Jebiruph's jumper, and I don't care what, if any, technique you introduce to take the ESS battery out of your vehicle's operation, you are, simply put, doing one of two things:

1) If you don't disconnect the negative cable on the main battery I discussed, you are putting both batteries in parallel at all times. This is a slight variation from SOP (standard operating procedure) where the batteries are in parallel at all times but ESS events and an instant prior to cold crank.

2) If you do disconnect the negative cable on the main battery I discussed you are removing the ESS battery from use in your vehicle.

In either case, any test of either battery by the vehicle returns one composite voltage that is a by product of both batteries connected in the first case, or just the main battery in the second case.

When the vehicle "sees" both batteries as having the same voltage, after 6 cold crank test occurrences, it assumes that there's a problem, i.e. a short between the batteries.

To the vehicle's computer, in either case, you haven't removed the ESS battery. In the first case you've simply hooked it parallel to the main battery, and in the second case, you've rerouted the ESS battery to only the main battery.

While I believe the above fact, I know the following opinion. I prefer to keep the vehicle with both batteries as per factory specs and put a trickle charger on the vehicle at rest. That isn't for everyone, especially those without access to external power where they park. But that's my way of addressing the fears we share in the ESS battery being the weak link here. I completely respect others opting to remove the ESS battery from the vehicle's electrical circuits, if not also literally and physically from its location under the PDS (Power Distribution Center.)

Thank you so much for taking the time to write this explanation. I share your view of not wanting the vehicle throwing unnecessary codes or stray from SOP.

Sounds like the best thing it to leave it hooked up, with ESS disabled via Tazer and carry a portable power pack (which I do) in case the battery gets pulled down.

 

[Jebiruph]

I think there's consensus here that in all but early model 2018 3.6L JLs without TSB 18-092-19 that

* once an initial failure to cold crank has occurred, and
* the vehicle has determined that the ESS battery (or what it thinks is the ESS battery given the various/alterative rewiring solutions offered above) is dead, and
* turns on the "ESS off" button in the EVIC,

that subsequent attempts to crank require one operator request and don't repeat this cycle.

What I question is how, once a working (or what the vehicle thinks via rewiring is the) ESS battery is reintroduced, how this cycle is broken, and the normal cold crank steps of testing the ESS battery are effected--which at least was my test finding and concurred by others here.

Does, for example, adequate voltage on the ESS cables tell the vehicle to restore normal crank steps on next operator request, or does the cold crank test of the ESS battery always occur, but the vehicle remembers that the test failed last time and as such immediately moves to a crank attempt against the main battery, or yet is some other mechanism at play?

TIA

@Jebiruph

I have no idea how that would work. Since the main battery is monitored by a battery sensor, the system has a good idea of it's status. The aux battery is not monitored by a battery sensor and as long as the batteries are in parallel, the status of the aux battery can't be determined. So you can't know the status of the aux battery without isolating it, but when it's isolated, it is the only source of power for the system electronics. If it doesn't have enough power to power the system electronics, the electronics shut down, which is basically how the cold start test works.

I didn't do extensive testing on mine, on both the updated JL and the JT, once I observed they were able to start with the aux battery disconnected and that the ESS stayed disable after the aux was reconnect, I cleared the error with a code reader or disconnecting both batteries. I did not test if there was some amount of time that the error would clear itself.

 

[NickV]

I am having the same problem. Replaced the battery, started, next time didn't start. Got a jump didn't start. Got a jump from roadside, it started but had a bunch of warnings. Went online and found the resetting the modules by turning the steering wheel left, right, left. back to center. That worked but 2 days later will not start. Hired a mechanic, replaced the Aux Battery and it started right up. Did not have to jump the main battery! I drove it for an hour, next day battery dead. Mechanic came over and got the car running, but it will not start after turning off. Got it started again and got these error codes: P1DD2, U1428 and P0562. Please help with solution

 

[mwilk012]

Check fuse N3

 

[andy29847]

The main. From my understanding, the auxiliary battery wouldn’t prevent the vehicle from starting.

Did you test the aux battery when you were replacing the main? I'd bet the aux is bad. Generally, you shouldn't put a new battery in parallel with an old battery.

My Jeep is a 2020, so I don't know much about your Jeep. Seems like I have read that there was a wiring change in mid year 2018 because owners were having trouble with starts.

 

[NickV]

Did you test the aux battery when you were replacing the main? I'd bet the aux is bad. Generally, you shouldn't put a new battery in parallel with an old battery.

My Jeep is a 2020, so I don't know much about your Jeep. Seems like I have read that there was a wiring change in mid year 2018 because owners were having trouble with starts.

I replaced the main and not the aux. I replaced the aux a week later. PS my Compass is a 2019.

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