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Discussion Starter #1
I know there are other threads about this problem, but I thought I'd ask for advice here since my dealership is being boneheaded.

Yesterday as I was leaving work (64 degrees out), my car repeatedly flashed the "battery too cold, plug in to warm" message. I drove half a mile to a charger and plugged it in (seeing this message flash up several times on the way), knowing full well it was not too cold. Charging stopped after 0.24kWh due to an unspecified interruption.

Onstar was unable to run a diagnostic. They tried twice.

I made it home with no issues other than the MIL and occasionally seeing this message. I plugged in and it charged for a while and then it stopped taking a charge. I re-plugged it and it finished charging successfully (240V).

My diagnostic dongle showed several DTC's:

7E0 P1E00 PowerTrain Confirmed Manufacturer Defined
7E4 P0A9E PowerTrain Confirmed Manufacturer Defined
7E4 P0A9C PowerTrain Confirmed Manufacturer Defined
7E0 P1E00 PowerTrain Pending Manufacturer Defined
7E4 P0A9C PowerTrain Pending Manufacturer Defined
7E4 P0A9E PowerTrain Permanent Manufacturer Defined
7E4 P0A9C PowerTrain Permanent Manufacturer Defined

Additional Information

PID Description Value Units
SAE 0x21 Distance traveled while MIL is activated 14.91 miles
SAE 0x30 Number of warm-ups since DTCs cleared 255
SAE 0x31 Distance traveled since DTCs cleared 6192.59 miles

The dealership just called me back and said it's fine and not showing any issues. Well of course not, it is an intermittent issue. It happened while I drove the car over there this morning. My fear is they will try to send the car home with me and I'll have to waste another day going back over there. Any advice on getting them interested in actually servicing the problem? I presume it's a bad connection in the traction pack, expensive to work on, and they want to avoid doing anything.

Thanks!
 

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Get a Volt Advisor involved to explain the issue to the dealer. I think they have the ability to read the past codes about it in the car, even if the engine light isn't on, so long as it happened "recently".

See here: http://www.dmaxcentral.com/fm1/index.php?threads/diagnostic-trouble-code-list.1481/
P0A9C - Hybrid Battery 1 Temperature Sensor Performance
P0A9E - Hybrid Battery 1 Temperature Sensor Circuit High Voltage

I had this temperature sensor issue with my wife's Volt. During colder weather (but nowhere near cold enough) it would very occasionally give this message. It typically boils down to an intermittent Voltage sensor in the pack that ends up reporting its maximum negative temperature value instead of the correct temperature. So the car gets confused and you get this message to appear. Other times it can be a control board causing it.

Either way, to get it fixed the battery gets opened up. Usually a section of the battery gets replaced which is apparently the only way to replace the faulty temperature sensors. It would be nice if there were a way to just replace the offending sensors and leave all the good LiIon in there, but that's not what happens. In my wife's case, this occurred twice, both times were faulty sensors from different parts of the pack. Each time they had to replace 1/3 of the battery pack. If it happens again, I'm mandating a new battery. ;)

Hope this helps!
 

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Discussion Starter #3
Thanks. I haven't dealt with any Volt advisors so I'm not sure what to expect there, but if the dealer gives me any more friction I'll get one involved.

As an engineer, I can appreciate the difficulty of diagnosing intermittent problems. You'd think if the pack has multiple sensors in each section and they deviated more than a certain amount, the control module would know a particular sensor (or connection) was bad, particularly if it failed open or closed. Expecting it to fail while on the shop floor seems like a bit much.

When I checked on the vehicle last night, the charge status light on the dash had turned back to orange. I'm not sure if that indicates it started to heat the pack rather than charge the vehicle--if so, that'd be really bad in the long term. All I did was unplug it and plug it back in and it went back to green.
 

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Usually orange means it is not charging and trying to negotiate a charge. I don't think it would be heating the pack; the other sensors wouldn't want it to do that.

I'm an engineer too, and also appreciate the issues with diagnosing intermittent problems. The thing that irks me is that the dealer often doesn't seem to want to bother to troubleshoot. Had they plugged in their code reader they would've seen the codes you saw, and would've been able to look up details about this sort of intermittent problem and the procedure to correct it.
 

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Discussion Starter #5
I don't generally watch my vehicle charge, so I can't say if it's normal for it to go from green to orange during the course of charging. It's the same behavior I observed at Whole Foods, only I didn't get a charge interruption notification from OnStar when I saw it at home. I've noticed that charge notifications are hit or miss though. I went about three months without a single one and then, for the most part, I started getting them again. I wonder if it's related to the problem OnStar had trying to diagnose the MIL? Or is this typical of what other people see?
 

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Orange light is not charging. Normally you get orange 1-2sec, followed by green and a short honk when charging starts.

Open the door and see what the cluster says, Not able to charge?

There's been several people who have had the pump or the battery heater intermittently fail.

The battery should be able to warm itself, it doesn't need to be plugged in to warm unless it's very cold or low on charge.

I'd say to take it in with a written statement. Take pictures of the errors with your phone.

If the car doesn't throw a code the dealership will just ignore it. That's how it is, they don't troubleshoot anything unless the computer tells them to, or you have compelling evidence that makes them need to do the work.
 

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Discussion Starter #7
The dealership insists the problem has to be reproducible in their service bay or they won't repair anything. They've charged it and driven it twice with no issues.

I tried to contact a volt advisor, but I get a DNS resolution error when I click the advisor chat link on MyVolt.

I guess I will just take it back when it happens again. This is maddening.
 

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The dealership insists the problem has to be reproducible in their service bay or they won't repair anything. They've charged it and driven it twice with no issues.

I tried to contact a volt advisor, but I get a DNS resolution error when I click the advisor chat link on MyVolt.

I guess I will just take it back when it happens again. This is maddening.
Call the advisor on the phone. Volt Advisor 877-486-5846
 

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Discussion Starter #9
Thanks for the phone #.

I got the car back and plugged in my OBD2 dongle 4 miles from the dealership and it already has a pending code. I called them back and they told me to bring it back to them once the MIL is illuminated & leave it running (that sounds completely unnecessary, but ok.)

They drove it 40 miles and could not make this happen? Amazing.

Does anyone know if this problem would be covered under the powertrain warranty? I'm still under a CPO bumper to bumper warranty, but I only have 4k miles left on it.

At least they washed it.
 

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I would think it is covered under the Voltec drivetrain warranty.
 
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