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Discussion Starter #1
My vehicle has had this error off and on for some time now. I'll give some backstory below:

02/2015: Vehicle purchased used from a Chevy dealership. 2012 Volt w/Premium Package. It has about 92k miles on it at the time.

07/2015: SHVCS message pops up. I bring it in to my nearest dealer and they have it for about 2 weeks. They determine that there is a path to ground within the battery system and that the entire battery pack would need to be replaced. I'm now out of warranty so the repair cost was about 12-14k. I decline the service because I could buy a whole new car for that price. I just drove it on gas.

01/2016: I make contact with an individual who put me in touch with the engineers that built the powertrain for the volt. The engineers look over my TAC cases and determine that the car has never received the HPCM update. They also told me that the dealership never opened a TAC case for the SHVCS issue in 07/2015. They instructed me to tell the dealership to perform that update. Once the update was complete, the car charged just fine. The engineers told me that the reprogram might hold forever or might just be temporary.

05/2016: SHVCS message pops up again. I take it back into the dealership and they report again that the entire battery pack would need to be replaced. So I again drive it on gas.

The good news for the rest of you is that the GM engineers told me that my car was the only high mileage volt to need a battery pack replacement. They told me that the SHVCS error was common in the SE USA.

I've since moved to a more populated area which I assume would see more Chevy Volts. Do you guys think it might be worth it to take it to my volt dealership here? The dealership I originally took my car to seemed like they knew what they were doing, but it seemed odd that they wouldn't have opened up a TAC case on the SHVCS issue.

The car still drives well, but I hate that I drive a practically value-less Volt.

Thanks!
 

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I think that dealer is trying to take advantage of you. The new battery is about $3,500. Dropping it and installing a new one is not $10k of labor. Not even close. Maybe 10% of that.
 

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You bought it with 92k miles, so I assume you were outside of the 100k mile Voltec warranty when this happened? Did they charge you for that software update outside of warranty?

I've heard of replacing certain sections of the battery, an entire replacement is rare. Have you taken it to another dealership for a second or third opinion? If not, I would highly recommend it.
 

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Discussion Starter #4
I haven't taken it to another dealer, but I did call another dealership to see what they would charge for a total replacement. They quoted me about the same price. It's been a while since I did that, but I believe they said the GM increased the costs because too many total replacements were getting done because the techs were not troubleshooting the system enough and just replacing the entire unit when it didn't need to be completely replaced. The battery itself is still $3500, but there are a ton of other fees placed on top of it and the install labor.

Yes, I am now out of warranty. I currently have about 129k miles on the vehicle. They did charge me for the software update. I think it was about $140.

I remember when I looked at the service manual for the Volt, it said for my error code basically that if all there troubleshooting steps turned out ok and the error still presented itself, to replace the battery pack.

I haven't had it seen my another dealer. I'm thinking about taking it to my new dealer where I live to see what they suggest.
 

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Yes, I was out of warranty when the issue happened. I'm now at about 129k miles.

I just contacted my dealer here to get an appointment setup. They said they just quoted out a battery replacement for someone and it came in around 8k.
 

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Unbelievable
So you've been driving for 30,000 miles unable to charge?

FYI the SHVCS message has NOTHING to do with your battery - NOTHING!
That message is for 1 thing and 1 thing only- an "indicated" detection of low battery coolant
If the coolant IS NOT low, then the coolant level detection system is flaking out and 99-times out of 100 the issue is the level sensor itself. (on very rare occasions it could be a bad connection at the level sensor or even a wiring issue in the sensor circuit but...)

-see this thread
http://gm-volt.com/forum/showthread.php?13194-quot-Service-High-Voltage-Charging-System-quot-Message

ALL you will need to do is replace the coolant level sensor with the replacement unit I designed, then attempt to clear codes (e.g. using Torque app and an ELM327 or some aftermarket scan tool)

IF they wont clear, then HPCM2 will need to be "reprogrammed" (by a dealer) to clear this annoying message FOREVER!

HTH
WOT
 

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Discussion Starter #7
Yes, I have.

If I put in your replacement sensor, and need to have the HPCM2 reprogrammed, won't the dealer know that I've made an aftermarket change to the car and not perform the reprogramming?
 

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No way !!!!!
 

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Just wanted to follow up and say that I'm back to driving on electricity again. I took it into a dealer and told them that I had a SVHCS issue and wanted them to specifically look at the coolant sensor. They looked at it and said that something was wrong with the wire that went to the sensor. They also said that when the other dealer programmed the HPCM2, that they neglected to program the BECM and that could have caused some issues too since they both should have been reprogrammed at the same time. He told me that he was shocked the other dealer didn't detect the problem right off the bat because it took them 30 minutes to figure out that it was related to the coolant sensor.

This is honestly a little frustrating. I'm not sure if it's related to poor training or what, but the fact that a dealership tried to tell me I needed to spend 12-14k to replace the drive battery when it was a $20 part is just dumb. I drove over 1.5 years on gas due to this.

Anyways, I'm back to charging again and am super excited! I'll be placing an order for WoT's sensor replacement soon!

Thank you guys for your help!

 
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