2022 Jeep JLU died

[aldo98229]

The higher voltage from the alternator overrides battery voltage, so I'm not sure how battery voltage comes into play on a running vehicle. Could it have been a bad ground cable that was corrected by the battery swap?

Perhaps. But that’d mean every other JL out there has a bad ground cable.

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[mwilk012]

The higher voltage from the alternator overrides battery voltage, so I'm not sure how battery voltage comes into play on a running vehicle. Could it have been a bad ground cable that was corrected by the battery swap?

On modern vehicles, the alternator does not run 24/7, and on our multiple battery setups, its even worse. A voltage fluctuation of any sort can cause spurious faults in multiple systems.

 

[Jebiruph]

On modern vehicles, the alternator does not run 24/7, and on our multiple battery setups, its even worse. A voltage fluctuation of any sort can cause spurious faults in multiple systems.

The alternator is running as long as the engine is running, it's the output that varies based on the PCM control. I'm not sure how a voltage fluctuation that is within system parameters would cause spurious faults, but faults in systems can cause spurious faults in other systems (or cause them to reset). Loose battery grounds can also cause spurious faults. And a side effect of replacing both batteries is that power is removed from the system long enough to power reset any malfunctioning module.

I'm not opposed to replacing batteries as a precaution as I've replaced most of mine (3 out of 4 - JL and JT) before they failed, but not everyone wants to buy new batteries if they are not needed.

 

[mwilk012]

The alternator is running as long as the engine is running, it's the output that varies based on the PCM control. I'm not sure how a voltage fluctuation that is within system parameters would cause spurious faults, but faults in systems can cause spurious faults in other systems (or cause them to reset). Loose battery grounds can also cause spurious faults. And a side effect of replacing both batteries is that power is removed from the system long enough to power reset any malfunctioning module.

I'm not opposed to replacing batteries as a precaution as I've replaced most of mine (3 out of 4 - JL and JT) before they failed, but not everyone wants to buy new batteries if they are not needed.

of course the batteries should be tested before replacement, but it’s simple fact that shorted cells can cause problems even while driving.

 

[Bikemobile]

Many of the factory batteries are poor quality. We’ve jumped and towed towed many many JL’s in the last few years.

Its actually an epidemic across all makes. Gm especially has a major issue with bad factory batteries.

 

[Jebiruph]

of course the batteries should be tested before replacement, but it’s simple fact that shorted cells can cause problems even while driving.

You make a good point, there are some battery failures that no amount of alternator output can cover up, like this Gladiator after having the batteries serviced by the dealer. https://www.jeepgladiatorforum.com/forum/threads/fire-fire-my-gladiator-burned-down.58206/

But in the context of typical battery failures being the result of the increased internal resistance of the battery reducing the ability of the battery to charge/discharge, this type of battery failure should have no impact on a running vehicle powered by the alternator.

 

[AlgUSF]

Many of the factory batteries are poor quality. We’ve jumped and towed towed many many JL’s in the last few years.

Its actually an epidemic across all makes. Gm especially has a major issue with bad factory batteries.

^^^^This

I remember back in the day when a factory battery could last you 5 years. Every vehicle I've purchased in the last 15 years has been lucky to make it to the end of the warranty period on the factory battery. On my Tundra, Toyota gave me so much drama replacing the battery at 32 months.

 

[josh405]

So update is their is NO update. Dealer called me Friday end of day. To tell me they they would not be able to look at it till Monday. No call today going to give till Wednesday afternoon to call if I haven’t heard from them by then.

 

[aldo98229]

So update is their is NO update. Dealer called me Friday end of day. To tell me they they would not be able to look at it till Monday. No call today going to give till Wednesday afternoon to call if I haven’t heard from them by then.

Yeah. That’s how dealers are.

After a month or two, you will be boiling in frustration over something simple that could have been resolved in a couple hours by someone competent.

 

[josh405]

Got the Jeep back yesterday. Tech was gone so was only able to talk to

my service advisor. Was a shorted connector behind the glove box that

took down the whole CAN BUS system so nothing was talking to each

other. The wire that was shorted headed from glove box area to one of the

rear quarter panels not sure which side. So it sucked it happened but dealer gave us

a 22 bighorn crew cab to drive and all seems good to go.

 

[RAIDEDR_JLU]

Any idea how they diagnosed that as the cause? I’m having similar (albeit different) issues with my Jeep dying while driving or not starting after a stop. Have had it towed twice. I replaced both batteries with new ones. Seated all fuses. Running out of ideas and Jeep is out of warranty of course.

 

[josh405]

Any idea how they diagnosed that as the cause? I’m having similar (albeit different) issues with my Jeep dying while driving or not starting after a stop. Have had it towed twice. I replaced both batteries with new ones. Seated all fuses. Running out of ideas and Jeep is out of warranty of course.

No idea unfortunately as the tech that fixed it was already gone for the day. Was only able to speak to the service advisor.

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