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Several months ago I brought my 2013 Volt in for service because the "Service High Voltage Charging System" warning was displayed, which it turns out was due to low coolant. So they fixed that and did some other software updates under warranty.

After I got the car back, I immediately noticed a loss of range, starting that day. I commute the same route every day, and I went from always getting 39-40 miles of all-electric range, to getting 32-35 miles. That's a 12-15% loss of range! This has remained the same since I got the car back. It has not varied with temperature, tire pressure, or other factors. (The climate here is very mild year round.) No CEL or other error messages.

Has this happened to anyone else after service, particularly software updates?

I will spare the details of my many conversations with both the dealer and the Volt advisor line, except to say that all the "customer service" reps I've spoken to are sure that the car is working right, and I just doesn't know what I'm talking about...

Service that was performed:

Program HPCM2 as directed by PI0961C.
13202 Power Inverter Module Reprogram Campaign S1B37
14617 Unintentional Engine Running Campaign BCM programming/setup S1937 FD66D

Probably unrelated:

Radio software update 805E7
Brake software update 28A97
14522 Emissions Noncompliance update
 

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Actual miles or are you referring to the dash battery range estimate?
 

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I tend to refuse to have software updates done, here in the UK. If I am happy with the way my car is, why change it? Whether or not something changes, you will always have that suspicion.

In the US, do you HAVE to have the updates, or can you refuse them?
 

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I tend to refuse to have software updates done, here in the UK. If I am happy with the way my car is, why change it? Whether or not something changes, you will always have that suspicion.

In the US, do you HAVE to have the updates, or can you refuse them?
I have refused #14617. But you need to refuse it on any and all future service visits or they will do it as S.O.P.

The one that started this for the OP was due to soft neglect of the battery TMS fluid level. Checking your fluid levels monthly is easy and fast. Especially in the 2011 and 2012's, the battery TMS fluid can slowly drop over time due to boil-off. Regardless of the year, if it's allowed to go too low (as in this case), the error is triggered and you can no longer charge the car. At that point, you MUST take the car in. On the other hand, if the loss of fluid is fast, there may be a leak. Another reason to check fluid levels regularly. If the error is triggered and fluid level is fine, chances are its a bad sensor or sensor wiring.

As far as I know, no one has seen a loss of actual driving miles after having the updates done. I cer
 

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Discussion Starter #6
This is loss of actual driving miles, not estimate. It's been driven through dozens or even more than 100 full cycles since the service (it's been many months.) The coolant loss was slow, no leaks were detected when they serviced it.
 

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I commute the same route every day, and I went from always getting 39-40 miles of all-electric range, to getting 32-35 miles.
Drive it through several full charge/discharge cycles http://gm-volt.com/2013/02/26/a-tale-of-two-volts-the-summary/ If you still have crappy range, take it back for service.
RVolt: This is critical.
We don't know your usage. Do you routinely run out of battery and go to gas? Or is your trip all electric?

The computer needs the car to exhaust the battery several times to "learn" what the battery's actual capacity is. If you don't run the battery all the way down, the computer cannot correct its math to give you the true battery range.
 

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There was a thread on here the other day about a bad HpCM flash process and that caused issues with range loss. Search for that.
 

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Drive it through several full charge/discharge cycles http://gm-volt.com/2013/02/26/a-tale-of-two-volts-the-summary/ If you still have crappy range, take it back for service.
^^^This^^^ A search of past postings will reveal to you that this is a normal occurrence. Your car has to learn anew your driving characteristics and the limits of the battery. A few discharges to CS mode should regain your true capacity and range.
 

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^^^This^^^ A search of past postings will reveal to you that this is a normal occurrence. Your car has to learn anew your driving characteristics and the limits of the battery. A few discharges to CS mode should regain your true capacity and range.
Several months ago...
How many month(s) of discharges should OP expect in order to regain his former range!?:confused:
 

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How many month(s) of discharges should OP expect in order to regain his former range!?:confused:
I think 'discharge to CS mode' is the critical issue. I haven't had that in several months myself, perhaps the OP has not either.
 

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How many month(s) of discharges should OP expect in order to regain his former range!?:confused:
Since the OP has not replied to the several times this has been asked, we don't know.
RVolt: This is critical.
We don't know your usage. Do you routinely run out of battery and go to gas? Or is your trip all electric?

The computer needs the car to exhaust the battery several times to "learn" what the battery's actual capacity is. If you don't run the battery all the way down, the computer cannot correct its math to give you the true battery range.
 

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Discussion Starter #14
Sorry for the slow replies, I'm a new poster so my posts have to be approved by the mods (edit: now it seems I'm past that)

I frequently do a full discharge cycle although not every day. But at least 2-3 times a week so definitely in the past several months it's happened many many times.

I had read some other posts referring to the peak capacity reset procedure and wondered if that might be a factor. My documentation from the dealer said they did the HPCM2 update but didn't specify if the reset was done. I also don't know if the peak capacity reset is needed every time the HPCM2 is flashed?

Full disclosure, I'm a software developer who writes embedded code for industrial systems (human and sensor input determines operating parameters... sound familiar?) So I am all too familiar with the pitfalls and challenges of updating such software, probably should have opted out in hindsight, although some of these updates did resolve other issues I was having.
 

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Sorry for the slow replies, I'm a new poster so my posts have to be approved by the mods
Sorry, forgot about that.
I frequently do a full discharge cycle although not every day. But at least 2-3 times a week so definitely in the past several months it's happened many many times.
Ok, that rules out that failure mode.
Sounds like you need to go back to the dealer, with a copy of the post about resetting the peak capacity.

Thanks RVolt, and welcome.
 

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Discussion Starter #16
Thanks for the suggestions. I found some other references to "Hybrid/EV Battery Pack Capacity Learn procedure as per GM global service document ID 2560214" which I think is the procedure.

Unfortunately my service write up doesn't say one way or another whether they did this procedure after updating the HPCM2. Also I couldn't find anything that said this is required when updating the software, only when replacing the HPCM2 which is a different thing. More info in this post here
 

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My guess is temperature change , sun exposure and ac usage . Here in TX , the past few months went from cool partly cloudy days to 97 degree sun drenched 14 hour days . My range dropped from 48 miles to 35 miles .
 

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My guess is temperature change , sun exposure and ac usage.
The dealership and the Volt advisors also used this reasoning to dismiss my concerns, unfortunately it ignores three rather important facts which I mentioned:
1. In the three years before getting the service done, the car never had this problem.
2. Over the past several months it hasn't varied with temperature - maybe a mile different on the coldest day but not 15%.
3. My climate is very mild - a "cold day" and "hot day" aren't that different in San Francisco...
 

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Not sure if this issue still exists, but there WAS bad software code out there for a while whenever a reflash of HPCM#2 occurred on 2013s. My car was the guinea pig in figuring out this problem.

The tell-tale sign is that you'll lose 5-7 EV miles when parking the car, unplugged, after driving for a bit. For example, I would park the car with 29 miles left for 30 minutes, come back and it would indicate 22 EV miles left. I was getting substantially less overall range and the kWh used was only showing 8-9.

More frequent stops, more frequent drops in range 5-7 miles (one day I actually only got 29 EV miles in CITY driving because I was making frequent stops, shutting off the car, and getting back in.

There are several threads on this, but here is the one with more information from my miserable experience figuring it out. At least GM took care of me in the end: http://gm-volt.com/forum/showthread.php?198114-Going-to-dealer-any-ideas-on-my-Volt-s-strange-issues
 

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Just throwing another possibility into the mix. You mentioned a brake system update. It could be that something was done to the brakes that resulted in a brake that is not fully releasing and is causing some drag as you drive.
 
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