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Discussion Starter #1
My 2012 Volt threw the dreaded "Service High Voltage Charging System" message yesterday evening.

The codes that appeared were P1E00, P1F0E & P1FFF. A "consumer" code scanner could clear the P1F0E code, but the other two would immediately reappear.

After doing some research on this forum, I gathered I was likely dealing with the "wonderful" cooling level sensor issues that are in marked sticky.

I also discovered that I my battery system coolant was at the "old" level, even though I had the Volt in for service several times since service campaign 14114 had been published -- so there was a possibility of of a "real" problem.

Given all of that, I took the car into the dealer this morning, and after a bit of a run around, I was told by the service writer that they "took apart all the connections and looked for corrosion and re-calibrated the charger" and that the error was cleared -- but because they did not find a failed component, this was not covered by my voltec warranty.

On the invoice, the notes include "reprogram HPCM2 with updates for modules and retest system". Unfortunately, the invoice includes minimal details and I will have to call for more details in the morning because I picked up the car after the service dept was closed.

Two main questions:
Should diagnosing a "P1FFF" Service High Voltage Charging System warning and reprogramming the HPCM2 have been covered under the voltec warranty?

Do the codes that I report indicate a coolant level sensor issue (and I should be shopping for the bypass plug ASAP) or does this combination of codes point in another direction?
 

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It should be covered under warranty, I would push them on it.

For mine, they had to redo two of the splices on the sensor wiring.
 

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Do the codes that I report indicate a coolant level sensor issue (and I should be shopping for the bypass plug ASAP) or does this combination of codes point in another direction?
FWIW: More than likely WOT's bypass plug would have prevented your unscheduled visit into the GM service dept...
 

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Discussion Starter #4
It should be covered under warranty, I would push them on it.
I intend to and have tried to get to a "volt advisor" (or whatever the correct team label is now) to help, but haven't had any success talking someone with Volt information beyond the "knowledgebase".

Are there procedure codes or documents that would be helpful in this situation? The service writer's handling was disappointing, and the service manager's initial response (before diagnosis was completed) was not helpful. I am hoping that more information will help....
 

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At first blush this was a problem created by the service department at the dealer, and consequently the dealer should handle it. Think about it. You're looking at error codes caused by the coolant level being too low. Assuming the dealer filled the tank correctly when it serviced your vehicle, then the only possible cause of the problem would be a loose connection, leak, or some other problem with the cooling system. However, the dealer has ruled these out, leaving as the only explanation a failure by the service department to to follow protocol and fill the tank correctly. Since this failure caused the error codes and the wild goose chase to find the root cause of the low coolant level the dealer should bear the cost of its negligent service.

Lots of less than stellar dealers out there.
 

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It seems simple enough to me. A Malfunction Indicator Light indicates a malfunction. How could they fix a problem and still claim it was not there?
 

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Discussion Starter #7
So, in doing more digging, it appears (at a minimum) that they did:

2810265 Hybrid Powertrain Control Module 2 Reprogramming

Increased the coolant level from the prior standard seam level to the top of the black label.

I can yet not confirm if they used PI0961 as their troubleshooting aid.

Is labor code 2810265 a "Coverage Code: V" task?
Would the diagnosis under PI0961 be considered a warranty item, or only if a "failure" is found?
 

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I have a 2013 Volt with 56k miles. It coughed up the P1FFF with the "Service High Voltage" message. I topped up all the fluid levels -- they were barely low, and got my non-chevy repair shop to clear all the codes. There were a bunch, because I first tried disconnecting the 12V battery and cross-connecting the positive and negative leads, in the hope that it would clear the P1FFF code.

After clearing the codes, the car was ok for about a day and a half, then the Service HV message showed up again. I had a big trip planned, so went ahead and drove the car in Mountain Mode all the time -- 800 miles. It did fine that way.

Finally, took it to the local dealer. They fixed it under warranty, so it didn't cost me anything. The repair page shows:

"Scan modules HPCM2 has codes. P1FFF and P0AA6 current. Scan check data. Isolation resistance is ok, at 325k ohms. Perform update on BECM and HPCM2 as per bulletin PIC5920. Also replace Coolant level sensor for high voltage battery pack with updated unit for P1FFF. Bulletin PI0961."

So here I am...
Still lovin' my Volt five and a half years in!!
 

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"...Also replace Coolant level sensor for high voltage battery pack with updated unit for P1FFF. Bulletin PI0961."
Glad they fixed it under warranty. This is the first time I've seen that there is an updated coolant sensor.
 

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Thanks for the detailed writeup Premeau. I have apparently the same symptoms so I figured I will share my data and experiences so far.

Model year 2012, ~97k miles on it (so nearing the end of the Voltec ptrain warranty) Car has been mostly trouble free.

Lead-up: Short errand in the morning after being fully charged overnight. Plugged in after errand, but then notification from OnStar that charging was interrupted. Car information display showed "Service High Voltage System". A second startup of the vehicle illuminated the check engine light as well. Code reader reported two codes "confirmed" and also "permanent" P1E00 (Hybrid Powertrain Control Module 2 Requested MIL Illuminated) & P1F0E (Battery Charging System Isolation Lost). It also showed P1FFF (not sure exact code description, but I have been told it's a catch-all that prevents charging while set) "confirmed", but not permanent. Car was driveable on electric, and showed its normal electric range, but would not charge. I didn't experiment with it much before getting it to the dealer. Our dealer is close so we didn't exhaust the battery before it went in for service.

Resolution: Dealer addressed the issue quickly, and at no cost to me. Invoice is fairly sparse. It says "reprogram the HCPM2 and the BECM". Technician found updates per bulletin DIC5920G. Reprogram modules HCPM2 code #CB157969179, and BECM code #CD15797388. I also spoke to the technician briefly who seemed to me to be pretty knowledgeable. I asked if battery coolant level had been okay: he said it was. I asked if isolation resistance was okay, he said it was. I asked if they removed the battery pack drain plug to check for leaks/moisture: he said he had and it was dry and good. I asked if he had any concerns with the wiring harness rework done as part of campaign 11342: he said he had inspected and it was good. I asked if he had any concerns with the coolant level sensor: he said it was okay. He explained that the issue was a false detect of low coolant, and that update/reprogramming was both to update code and also to recalibrate the limits for the modules(s) to avoid this nuisance detection.

I'm very happy they covered it and we didn't have to have uncomfortable conversations about warranty coverage. I'm happy they made their technician available for me to ask questions. I am a little uneasy that the issue could come up again, so I'm hoping it does not.

Final note: I did buy a defeat plug, but like a couple others I've seen on here, I hadn't installed it yet. I was concerned that installing that plug could cloudy the waters if I had any type of warranty claim in my last few thousand miles of coverage. I'm half glad I didn't install the plug yet (because if the issue occurred, I would definitely be scrutinizing the plug or my install procedure), but I'm half annoyed I didn't, because if the issue is truly a sensor that is failing then the plug would have prevented this issue.

-Arthur
 

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Discussion Starter #13
Glad it worked out for you. It ultimately did for me as well, but in my case it took standing behind the service manager as he looked up the task, and talking to the general manager of the dealership. They finally agreed that that they were seeing something different than the usually saw on a programming task that they called their GM rep, who quickly confirmed it should have been covered under the Voltec warranty.

It was the first (and probably only) time that I got a dealership to cut me a refund check.

I relocated across the country, so I invested in the usb interface (and the subscription from GM) to allow me be more self-sufficient in this times of "computer only issues. I installed my sensor defeat plug after I crossed 100k miles -- was fully prepared to reprogram the HPCM2 myself.

(I probably would have gotten the tools if I had not moved, but the move made me realize how important it is to be self-sufficient when there is not the opportunity to build a mutually trusting relationship with a dealer.)

Steve.
 

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One possible info point:

"that update/reprogramming was both to update code and also to recalibrate the limits for the modules(s) to avoid this nuisance detection. "

the limits may be ONLT the voltage issolation and not the resistance of the float switch IE a battery tank level float switch can still trigger a CELL lock out

++++ UNLESS this new software makes it a NON lock out error needing a re-programming each time .
 

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Thanks for the detailed writeup Premeau. I have apparently the same symptoms so I figured I will share my data and experiences so far.

...

-Arthur
Got this error today and went grave digging.

Now ~95K miles on the meter. I'll post my experiences later when the car is serviced.

Somewhat luckily I've already put out a service time for the car as in the spring time it developed the "Propulsion Reduced" symptoms when battery was just drained when car was stopped and then restarted 15mins later. Just wondering if these might be linked (or just random timing).. 28th that is, if the car still starts at that point.

Additional note is that the battery got changed to a refurbished one few years back.
 

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Now fixed, two software updates. First the paper pusher tried to charge me for it, but after me noting the VolTec warranty charges were dropped. Paper pusher did not show me the mechanics notes, just noted that (translated from Finnish) "High Voltage Battery Controller" and "Transmission unit controller" were upgraded.
 

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Hi, Russella, do you or anyone have a copy of that TSB # DIC5920G that you mentioned? I cannot find it anywhere online, but I believe I just had the exact same problem with my 2012 Volt, and was charged by the dealer for repair. Would love to get my hands on a copy to go back to the dealer with. Thanks!!
 

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The dealer didn't give me any more information on that bulletin. I saw it on the work order and posted it here, but unfortunately that's all I have. Sorry!
 

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Update: Now at 96300 miles and the error is back.

Next available service time is somewhere in August (as Volt techs are on summer vacation) :p
 

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Now the car is at dealer for problem diagnostics. Let's see what the find out.


While dropping it in I got also record from previous service:
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Coolant level check - little low, added (no mention that leakage test would have been done or even drain-plug check. Shouldn't this be done if level is low?)
Floater movement check - ok
Sensor removal & check - open 3.53V, closed 2.1V
Sensor circuit input/ground check - ok
Sensor wiring check
HPCM2 vs B258 = 55W test ok / ground ok / voltage ok / insulation 100V ok (wiring ok)
HPCM2 data (isolation test 1200kohm)
HPCM2 data list saved
HPCM2 sps reprogram (clears the dtc P1FFF)
Test drive with empty battery = no problem
Re-test drive + charge battery + re-test drive
dtc check = no-codes / no issues with gas engine
HPCM2 (isolation test 1150kohm)
BECM reprogram = ok
Battery heater check = activating heater did not raise voltage difference between main busses = possibly ok
Isolation test = 3000kohm = ok
DTC check = ok
Charging test = ok
Test drive = ok
-------------------------
 
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