Call OnStar and ask them to give you the codes it was throwing.

 

Yeah, hopefully it ends up just being a software update for ya. Thanks for testing for the rest of us too ;-)

 

A few Hummers have had issues with "hybrid battery system" I wonder if they are still working out the kinks on the wireless communication between modules.

 

I appreciate the information. This is much more helpful than than my call to the service department. Thanks!

 

I’ve read recently that some codes are distance and time related. Thus a charging error could have been caused previously, if that was a catalyst at all. Also you would receive an email or message if there was a charging error.
Love this truck more than anything else I’ve owned, and I’m not a truck guy. This one’s hard to beat…

 

Thank you for the prompt response! The error code is: U359B (“hybrid battery system”).

 

Thats the “check engine light” basically. Needs diagnostic but if it wont go past 80% possibly module issue in battery pack

 

The vehicle ended up staying at the dealership service center for a week. The technician communicated back and forth with engineers at GM corporate and no issues were found. They reset the light and were able to charge and drive the vehicle normally again. My fingers are crossed that the light does not come on again.

 

Got to remember the Hummer is the first truck with a wireless BMS... 24 of them. So it might be a firmware issue where it doesn't get as strong a signal as it expects and tosses errors.
Something that will be refined over time.

 

Back around Nov 10th got the vehicle indicator light and codes P1E00 & P0F3B. When I took it in I was told the heater needed to be replaced, which was taken care of at that time.
Last night when I was running to the store got the same indicator and called OnStar and got the exact same two error codes as before.
Needless to say I wasn't thrilled to have the same issue twice in a months time span. I checked it again this morning and the light was still on. I decided then that I would take it to my shop to pick up my other truck till I could get it looked at. I remote started the hummer for about 10 minutes and when I got in the indicator light was gone and called OnStar and there are no longer any codes in the system.
The constant between these issues is the outside temp was below 45F during the start up of the vehicle. OnStar did recommend pre-conditioning the vehicle in cold weather and hot weather to get everything to optimum condition. They said they weren't sure what caused it to go away since there was no service done to it the second time.
I am waiting to see what happens this weekend as it will be the first extended period of time with freezing temps for my area.

 

I got the same codes from OnStar. It sounds like your hummer is experiencing a software glitch or anomaly. I initially disconnected the ground for 15 minutes to reset the vehicle, and it worked. However, two things I learnt that you need to be aware of.
Disconnecting the battery could cause your infotainment system to go into Theft Locked mode. I took mine into two different dealerships and I do not believe they know what to do. It limits several features, speed limited to 56mph, zero use of the infotainment system, suspension stuck entry/exit mode. I have tried every possible option including removing both negative and positive terminals from the battery for about an hour. Did not work however unsure if leaving it disconnected for a longer period would work. I purchased an OBD device that should solve this theft locked issue, receiving it tomorrow.
The second thing that would potentially cause the software anomaly is the charger itself. If the charger doesn’t get the proper amperage/voltage, it would send signal to the vehicle that may cause these redundant codes. You need to ensure that the removable plug on the charger is seated perfectly inside the port of the charger. Press it in using force against another object. That worked for me more than once. Good luck.

 

I know this is an older thread but this happened to me today with my Hummer EV at 3500 miles. Not always the solution, but I followed the steps on this page and it resolved it for me. Good luck. Site Maintenance

 

I know this is an older thread but this happened to me today with my Hummer EV at 3500 miles. Not always the solution, but I followed the steps on this page and it resolved it for me. Good luck. Site Maintenance

I get the warning light about 1x a quarter, not frequently enough to draw any correlations.
otherwise truck is flawless

 

Just got this warning light myself and am waiting to take it in. Was the fix minor or substantial?

 

Thanks for the reply. I am hopeful that is my result too. The vehicle seems fine aside from the light being fine, but we will see…

 

I would have liked to know the codes it is throwing.... @JackBurton you can call Onstar and request the codes.

 

P1E00

The Drive Motor Control Module is not performing as expected. An issue has been detected in the Motor Control System which monitors and controls the electric motors used to propel your vehicle.

P0F3B

The Lithium-Ion Battery is not performing as expected. An issue has been detected in the Battery Conditioning System which provides heating and cooling for the battery pack on your electric vehicle to ensure efficient operating conditions.

 

I'd take that in, check if there are any firmware updates and have them check the coolant levels...

 

Thank you. Taking on Monday (my first opportunity). Not looking forward to letting it sit there forever while they scratch heads, but will pass your suggestion along!

 

As a Stop-Sale waiter I'd trade positions with you.

 

Keep me posted as I have the same warning light. Local dealer says there were communication errors according to GMC. Initially they were going to change the battery pack but now dealer says GMC think it’s a firmware issue. I really don’t know honestly. My truck still drives and charges fine so I have been driving it and waiting.

 

An orange warning light showed up this week. The manual said something about “Propulsion System Failure.” Initially, the light came on intermittently and now it is constantly lit. The service dept said they can not look at the vehicle until next week. Also, my vehicle has not been charging to 80% the last two days. Any advice would be appreciated! View attachment 3330

I was just doing the same Saying. Do you know if it's gonna hurt to drive Yet are we supposed to park it or what ? will it charge

 

I got the same error code and CEL as of today. Had it plugged in charging at my house, and then when I went in to drive it, saw the CEL. Called OnStar and they diagnosed and gave me those codes as well. Mine is a 2022 as well

 

Just got the light, Onstar confirmed the following codes (1900 miles):

1.) P1E00
2.) P294F -

The Lithium-Ion Battery is not performing as expected. An issue has been detected in the Battery Conditioning System which provides heating and cooling for the battery pack on your electric vehicle to ensure efficient operating conditions.

any color on if this is just software, or more invasive?
Also looking for a trusty/decent dealer in Denver area, not a fan of Alpine

 

The same happened to me a couple months ago. Are you guys using the provided Ultium charger?

 

How was your issue resolved?

I am using the provided charger, I don't drive much so I tend to plug in every 3-4 nights.

 

Thanks @kevlutch - appreciate the response. my truck wasn't plugged in overnight, so i can rule out that potential cause (assuming today was the first day the light came on, it's fairly inconspicuous).
I waited an hour, then started the truck and the light was still on, I pulled out then immediately returned because I forgot something at home. I turned it off, ran inside, then back to the truck, when I restarted, the light was gone. Maybe 1-2min passed.

Another owner mentioned it could be temperature related, and our overnight low was ~45f, but my garage was certainly warmer than that.

I'll keep an eye on it, and check the pre-conditioning settings (I believe I have that set to on bc i don't care about max range). Maybe I also need to make sure its plugged in more often, and/or on cold nights.

Sorry about your troubles after disconnecting the battery, it sounds like when I try to take on a project at home... best intentions leads to weeks of headaches.

 

It happened to me also 2400 miles. truck had 700 miles at the dealer since June 2023.
we use 48 amps at home to charge. I floor it all the time! I have not called for the codes yet,
But i bet it is the same. It doesn't sound like anyone really knows yet? except i have not seen
anything catastrophic mentioned yet.

 

Got it on mine yesterday while out. 6 months old with about 5K miles on it. Drives normal, charges fine and everything seems normal. Onstar cant find codes and nothing is else is popping up with any info. Seems like an eroneous light at the moment.