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Discussion Starter · #1 ·
Curious if anyone else is having the intermittent issue of their Hummer EV not going into drive or reverse? I’ve had mine for about 4 months now and roughly 3000 miles put on it. Every now and then the main 12v battery, just like all vehicles have, that is used to turn on the main battery seems to lose charge. I have read other stories where people were stuck and I had this happen to me when it was first delivered. My local dealer is absolutely terrible and they really have no information so instead of letting it sit there for days at a time to get it back and be told that either they can’t figure it out or it’s fixed, to then happen again I decided to try to figure it out myself. I was told that the main vehicle charger does not trickle charge that 12 V battery which seems odd. This battery is used to run the fans which cool the main battery when it is hot outside which would drain it pretty good I imagine as well as updates, etc. I have noticed that the times have this issue is when it is hotter outside and I‘m using it driving around town to my business locations. I have found that if I use a trickle charger every few weeks to keep that battery at full charge I do not get this issue where it will not go into drive or reverse. It’s just frustrating because we should not have to trickle charge the 12v battery. The GMC dealer hooked up the battery to their battery tester that takes about 20min to give a result and it checked out fine. Since I have been trickle charging that battery I have not had the issue, but if I do not do this, then after a couple of weeks I will randomly go places and not be able to get it in to drive or reverse, sometimes taking 15 or 20 minutes to resolve the issue (I have found locking the vehicle and walking away for about 5 minutes solves it most of the time oddly enough). On days where this happens I just never turn the main battery off once I get it started. When I recharge the 12v fully I will do a hard reset by disconnecting the terminal for 30 sec, after that I will not have the issue at all unless that battery is able to drain down to less than 25%. Surely GMC will come up with a way to resolve that issue, I can’t be the only one experiencing it.. Hope that helps anyone else having the issue as well get by until GM or dealers figure it out. Otherwise if you bring it to your dealership it’s just going to sit there and not get resolved_
 

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Volt, Polestar 2, R1T, Livewire One
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The dealer should be able to diagnose the issue, but they might have to get a GM Engineer to help them out with it. Mine didn't have issues with it killing the 12V batteries but there have been several complaints here.
 

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Curious if anyone else is having the intermittent issue of their Hummer EV not going into drive or reverse? I’ve had mine for about 4 months now and roughly 3000 miles put on it. Every now and then the main 12v battery, just like all vehicles have, that is used to turn on the main battery seems to lose charge. I have read other stories where people were stuck and I had this happen to me when it was first delivered. My local dealer is absolutely terrible and they really have no information so instead of letting it sit there for days at a time to get it back and be told that either they can’t figure it out or it’s fixed, to then happen again I decided to try to figure it out myself. I was told that the main vehicle charger does not trickle charge that 12 V battery which seems odd. This battery is used to run the fans which cool the main battery when it is hot outside which would drain it pretty good I imagine as well as updates, etc. I have noticed that the times have this issue is when it is hotter outside and I‘m using it driving around town to my business locations. I have found that if I use a trickle charger every few weeks to keep that battery at full charge I do not get this issue where it will not go into drive or reverse. It’s just frustrating because we should not have to trickle charge the 12v battery. The GMC dealer hooked up the battery to their battery tester that takes about 20min to give a result and it checked out fine. Since I have been trickle charging that battery I have not had the issue, but if I do not do this, then after a couple of weeks I will randomly go places and not be able to get it in to drive or reverse, sometimes taking 15 or 20 minutes to resolve the issue (I have found locking the vehicle and walking away for about 5 minutes solves it most of the time oddly enough). On days where this happens I just never turn the main battery off once I get it started. When I recharge the 12v fully I will do a hard reset by disconnecting the terminal for 30 sec, after that I will not have the issue at all unless that battery is able to drain down to less than 25%. Surely GMC will come up with a way to resolve that issue, I can’t be the only one experiencing it.. Hope that helps anyone else having the issue as well get by until GM or dealers figure it out. Otherwise if you bring it to your dealership it’s just going to sit there and not get resolved_
Software definitely up to date? One of thr first two updates had 12v maintenance feature in it.
 

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Discussion Starter · #4 ·
Yes, I did update software each time the new ones have come out, 2 I think so far. The last one gave me the Extract Mode. I thought that was it for sure, so I quit charging the 12v battery and it did it again this week.
 

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Discussion Starter · #7 ·
You are probably right, depending on the heat and how long they sat I wonder if it causes the battery issue. I guess I’ll have to bring it back to the dealership at some point or just bite the bullet and buy my own battery. Thanks for everyone’s input.
 
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