Charging System Voltage High Code Keeps Popping Up

[Not2Late]

Happy Friday - here's a weird one and looking for some insights!

I have a 2021 Mojave, 26k miles. About 3 months ago, it started up fine and I went to the store. When I started it again after shopping, it fired up, but the dashbard lit up like a Xmas tree. Seems like all the yellow trouble lights were on and there appeared to be no ryhme or reason - some were traction control, others where warnings about lane departure not available, etc. The radio screen was blank and the jeep would not shift out of park. I turned it off ("Hello, this is IT, have you turned it off and on again?"). When I started it up again, everything seemed fine with the exception of the check engine light. Code was P2504 - Charging System Voltage High.

Took it to the dealer. They checked it out and checked the charging and starting system and noted that all checks were clear. Cleared the code and gave it back to me. Well, today it did the same exact thing, same code, and I have an appointment to take it in again. I should have taken a picture of the dash, but I was momentarily pissed and didn't before shutting it off again. I am anticipating a similar dealership finding(s) as the last time and I am worried this is going to be a continuing issue.

The jeep has had all of the power control module and software recalls/updates.

So, my question is has anyone experienced this and what was the ultimate fix/outcome. Want to be armed with this information when I visit the dealer again next week. Any information would be really appreciated.

Thank you!

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[Mr._Bill]

Have your batteries tested. Low voltage causes odd computer errors. Battery problems will cause the charging system to run at maximum.

 

[Lunentucker]

2.5 years on mileage that looks like a daily driver in Kansas. You need two batteries.

 

[Lost1wing]

Do we have smart alternators on our JT's? Output of that type is controlled by the ECU. Someone talked about this before and the voltage supplied to the battery could be quite high. Just an idea, what do I know.

 

[Rusty PW]

Do we have smart alternators on our JT's? Output of that type is controlled by the ECU. Someone talked about this before and the voltage supplied to the battery could be quite high. Just an idea, what do I know.

We have "smart alternators".

 

[ShadowsPapa]

Do we have smart alternators on our JT's? Output of that type is controlled by the ECU. Someone talked about this before and the voltage supplied to the battery could be quite high. Just an idea, what do I know.

Not high enough to trigger that sort of issue. They will max out at about 15 volts.
The ECU controls alternator output based on battery temperature, the amps out vs. amps in history, engine torque and other factors.
If it's high, there's a problem. There will be a maximum regulated voltage - sounds like his has exceeded that. It won't keep cranking up the voltage until things blow.

 

[ShadowsPapa]

We have "smart alternators".

Naw, some idiot blogger started calling them that. They are puppets - the ECU is the real puppet-master. The alternator has no brain.
But ok, fine, whatever the dopes that write for the auto magazines say - they are "smart" (but really, it's the ECU that's smart - my Delco 10si from 1982 is smarter)

 

[ShadowsPapa]

Do this - take the IBS off the main battery. Charge the batteries with a good AGM battery charger.
As long as the IBS is off for 10 minutes or so, it will reset.
See how that goes.

 

[Lost1wing]

We have "smart alternators".

I just found where I saw that here. You were in that thread too. It was regarding a question of the ecodiesel and if it had a smart alternator.

It was mentioned that the PCM controls the alternator. From what I read about these alternator types, voltage could get up to 18v on a cold start in cold weather. A weak battery or shorted cell could cause high charging voltage.

 

[Lost1wing]

Naw, some idiot blogger started calling them that. They are puppets - the ECU is the real puppet-master. The alternator has no brain.
But ok, fine, whatever the dopes that write for the auto magazines say - they are "smart" (but really, it's the ECU that's smart - my Delco 10si from 1982 is smarter)

Yes, the pcm is the control and the alternator is doing what it is told.

 

[Not2Late]

2.5 years on mileage that looks like a daily driver in Kansas. You need two batteries.

Yeah, I am starting to think this may be the case. I can't believe though only 2 years in. But, I have seen others posting about batteries not lasting long. Can't wait (in a wierd sort of way - I mean who pines for getting past the warranty period??) until I am past the warranty period someday and I can try to ditch the dual battery ESS system. Seems to be the culprit in more than just a few electrical issues as some folks have observed. I do miss the last "simple" versions - pre '18 wranglers! Ok, old guy rant over.

I am going to specifically ask them about testing the batteries. Not sure when they reported that "everything checked out" when I took it in the last time included that.

 

[Not2Late]

Do this - take the IBS off the main battery. Charge the batteries with a good AGM battery charger.
As long as the IBS is off for 10 minutes or so, it will reset.
See how that goes.

I am going to ask the dealer to do something like this - test the batteries to make sure they are good. I figure as long as it is under warranty, I am going to let them mess with it. But I may be a "helpful" customer with some suggestions. I am sure they will love that! Wouldn't it be nice to have a forum app where you can have 4-6 of us on video looking over the shoulder of one of us when we go into the dealer. Ha!!, I've brought my committee in with me today

 

[Lost1wing]

Is there a dealer service center score card? That is what we need to create here on this site.

I would certainly try what Shadowspapa suggested before heading to the dealer.

 

[Uparms]

Any rain, puddles or water involved either time?

 

[Not2Late]

Any rain, puddles or water involved either time?

No water involved at all - besides my tears of rage

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