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Discussion Starter #1
So, I drive home in my Subaru yesterday (after a rain storm) and my garage circuit has a tripped breaker, as well as the breaker for the circuit for the crawl space. Weird. My 2014 Chevy Volt has been plugged in while I was gone (but it had already finished charging). Today I wake up and I have the "Service High Voltage Charging System" error on my dash.

I figure that it may have something to do with the "power surge" or whatever happened yesterday, although my Clipper Creek L2 240 Volt wall charger is showing no error codes on it. (It is hooked up to its own dedicated circuit.) I pop the hood of the Volt and check the charging & ECU related fuses, and they all check out OK.

I'm guessing that it may be related to the power issue from yesterday, but then again, maybe not.

Also, all 3 of the coolant fluid reservoirs are filled properly, so it's not a low-fluid issue, although I guess it could be a related sensor.

Any ideas??? I do not have access to read error codes.
 

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Are you able to charge the car? At my work several years ago they installed 6 level 2 charging stations. We used my 2011 to test them. There was a problem with one of the stations which threw a check engine light on my car. I do not recall "Service high voltage charging system" warning, but the check engine light went off in a couple days on its own. I never lost the ability to charge and everything seemed to be fine.
So, if you are still able to charge, maybe it will clear itself?
 

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Discussion Starter #3
I am not able to charge.

BTW, since starting this thread, I re-signedup for On-Star, and they were able to read the fault codes. They send me an email with details about the fault(s) they read, which I have listed below:


The code(s) and explanation(s) associated with this issue is/are:

P1E00 The vehicle's electric system is not performing as expected. The HPCM (VIC) may or may not have another code active. If no other code is found service at your convenience.

U185A The Emissions System is not performing as expected. An issue has been detected in the Evaporative Emissions System which prevents the escape of fuel vapors from the gasoline in your fuel tank and fuel lines. The following may correct an evaporative emission malfunction: - Check that the fuel cap is fully installed. If you determined that the fuel cap was not seated properly, a few driving trips with the cap properly installed should turn the light off. - Ensure that good quality fuel is used. If fuel below vehicle standard, as noted in the owner manual, was used, it may require at least one full tank of the proper fuel to turn the light off. If these conditions do not apply or are not corrected with the recommended actions, please have your vehicle serviced.

P1FFF The Lithium-Ion Battery is not performing as expected. An issue has been detected in the Onboard Charging System which manages your vehicles battery pack charge level.



Based on the results, you should service your Chevy at your convenience.
 

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While under hood how was the battery coolent fluid level ? near the top of the label at the top of the tank ?

U185A The Emissions System error may clear and not part of a "won't charge" problem

Try a few start -drive -stop cycles then get a new set of codes.

and try charging at a second location.
 

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Discussion Starter #6
Yes, the coolant reservoir was filled to the proper level.

UPDATE:

A few days after my first call to On-Star, I called them again and got another diagnostic, as follows:

The code(s) and explanation(s) associated with this issue is/are:

P1E00 The vehicle's electric system is not performing as expected. The HPCM (VIC) may or may not have another code active. If no other code is found service at your convenience.

P0AA6 The Lithium-Ion Battery is not performing as expected. An issue has been detected in the Hybrid Battery System which is a high voltage battery used to propel your vehicle.

P1FFF The Lithium-Ion Battery is not performing as expected. An issue has been detected in the Onboard Charging System which manages your vehicles battery pack charge level.

I brought my Volt into the Chevy dealership, and they:

1.) Reprogrammed the HPCM2 module (free of charge), per P0AA6 fault code.

2.) Replaced the coolant level sensor and connector for about $310, parts and labor, per the P1FFF fault code.

This sounds about right, as other posts I have read on this forum have had the same issues/fault codes, and their dealership recommended and performed the same fixes as mine.
 

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I brought my Volt into the Chevy dealership, and they:

1.) Reprogrammed the HPCM2 module (free of charge), per P0AA6 fault code.

2.) Replaced the coolant level sensor and connector for about $310, parts and labor, per the P1FFF fault code.

This sounds about right, as other posts I have read on this forum have had the same issues/fault codes, and their dealership recommended and performed the same fixes as mine.
Will you be installing the WOT sensor replacement to prevent a reoccurrence? GM should have fixed this problem part long ago; some people have replaced the part multiple times.
 

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Discussion Starter #8 (Edited)
No. Not in a zillion years.

A defeat plug on a windshield washer fluid reservoir? Yeah.

A defeat plug on a coolant reservoir that protects a 360 volt battery pack? Not in a zillion years.

It's not just a question of warranty. Its also a question of safety. BIG TIME.
 

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there is a service report on this
Replaced the coolant level sensor and connector "

As ammunition for potential warranty coverage for any necessary repairs to the RESS coolant LEVEL condition, there HAS been a recent preliminary service bulletin PI0961 released that outlines revisions to the diagnosis and repair of a DTC P1FFF.

https://gm-volt.com/forum/showthrea...coolant-sensor-and-module-reprogramming/page2


See the last post in that thread

A couple weeks ago I got the "Service High Voltage System" alert and a CEL. I took it to Reliable Chev in ABQ who immediately told me it was covered under the voltec warranty.

-------------
https://static.nhtsa.gov/odi/tsbs/2013/SB-10052204-6977.pdf

SERVICE HIGH VOLTAGE CHARGING SYSTEM Message Displayed on Driver
Information Center
 

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No. Not in a zillion years.

A defeat plug on a windshield washer fluid reservoir? Yeah.

A defeat plug on a coolant reservoir that protects a 360 volt battery pack? Not in a zillion years.

It's not just a question of warranty. Its also a question of safety. BIG TIME.

The battery has other safety devices to prevent a problem with low coolant. The coolant sensor is a known issue because it is a jerry-rigged retrofit that GM has shown no interest in resolving. Having you make many dealer visits is fine by them and the dealer. And it's known to have the same issue come back after replacement, again, and again, and again. I (and others) have had the defeat on our cars for years, zero issues. But hey, do what you want. There's nothing better than dealer waiting room coffee and the TV set to daytime soaps. :)
 

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The battery has other safety devices to prevent a problem with low coolant. The coolant sensor is a known issue because it is a jerry-rigged retrofit that GM has shown no interest in resolving. Having you make many dealer visits is fine by them and the dealer. And it's known to have the same issue come back after replacement, again, and again, and again. I (and others) have had the defeat on our cars for years, zero issues. But hey, do what you want. There's nothing better than dealer waiting room coffee and the TV set to daytime soaps. :)
Do you know of WOT is still selling the defeat?
Thought I read this was improved so as to not be much of a problem on 2014 and 2015's, and a non issue on Gen 2's?
 

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Do you know of WOT is still selling the defeat?
Thought I read this was improved so as to not be much of a problem on 2014 and 2015's, and a non issue on Gen 2's?
WOT went AWOL. But there are others selling it, they are in that thread toward the end.

This is a Gen 1 issue as far as I know, not Gen 2. Definitely 2011, 2012, whether later years are affected I don't know but would not be surprised.
 

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Concerning the draconian response of the Volt's computers to a low battery coolant signal, I would suggest that GM was probably hemmed in very tightly by some legal contract with LG Chem as to how batteries were protected. My guess is when things get hinkey like this, lawyers were probably involved.
 

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Concerning the draconian response of the Volt's computers to a low battery coolant signal, I would suggest that GM was probably hemmed in very tightly by some legal contract with LG Chem as to how batteries were protected. My guess is when things get hinkey like this, lawyers were probably involved.
We are talking Gen 1 Volt here, not Bolt. And it was politicians not lawyers that were involved.

The sensor was added after the Republicans in Congress held hearings about the safety of this new EV after a pre-production crash tested Volt caught fire 3 weeks later after the junk yard 1) failed to disable the battery, and 2) stored the crash damaged car upside down on its roof. The Republican show boats fanned the flames so to speak, but eventually their "investigation" yielded nothing but creating unwarranted fear.

GM's response was to add this sensor and beaf up the battery tunnel. In case you are in a crash and are rolled over on the roof, instead of having 3 weeks to exit the car before it may catch fire, you now have may 4-6 weeks to get out of the car.
 

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We are talking Gen 1 Volt here, not Bolt. And it was politicians not lawyers that were involved.

The sensor was added after the Republicans in Congress held hearings about the safety of this new EV after a pre-production crash tested Volt caught fire 3 weeks later after the junk yard 1) failed to disable the battery, and 2) stored the crash damaged car upside down on its roof. The Republican show boats fanned the flames so to speak, but eventually their "investigation" yielded nothing but creating unwarranted fear.

GM's response was to add this sensor and beaf up the battery tunnel. In case you are in a crash and are rolled over on the roof, instead of having 3 weeks to exit the car before it may catch fire, you now have may 4-6 weeks to get out of the car.
Wow. That is some super interesting history, thanks for the post.
 

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Discussion Starter #16 (Edited)
A few years back, I was driving my Volt 70 mph on the interstate and hit a piece of road debris. I pulled over at the next exit, and visually inspected the damage. It appeared to be only superficial to the front of the Volt, so I got back in the car and continued to drive.

Soon after, the "Service High Voltage System" warning appeared on the dash. I pulled over again, and reinspected the car, this time popping the hood. There was more damage than I initially thought, including punctures to some radiators and damaged some other internal hardware, draining the coolant in that reservoir. That "useless sensor" had done its job and sensed that the coolant was gone, thrown a code, and properly cut-off certain functionality to the Volt, including charging.

I really hope people with that bypass sensor don't encounter a similar situation, and charge their Volt with no fluid. I'm guessing the motivation for Chevy installing that sensor was seeing others in my situation, and charging their Volt with no fluid, creating issues, possibly dangerous issues.

Yeah, sometimes lawyers make manufacturers do stuff, but most of the time, necessity and common sense rule judgement and decisions.

I'm an Engineer with years and years of experience working in the automotive industry, including manufacturing, software diagnostics, and aftermarket. I've seen it all over that time.

But hey, do what you want.
 

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A few years back, I was driving my Volt 70 mph on the interstate and hit a piece of road debris. I pulled over at the next exit, and visually inspected the damage. It appeared to be only superficial to the front of the Volt, so I got back in the car and continued to drive.

Soon after, the "Service High Voltage System" warning appeared on the dash. I pulled over again, and reinspected the car, this time popping the hood. There was more damage than I initially thought, including punctures to some radiators and damaged some other internal hardware, draining the coolant in that reservoir. That "useless sensor" had done its job and sensed that the coolant was gone, thrown a code, and properly cut-off certain functionality to the Volt, including charging.

I really hope people with that bypass sensor don't encounter a similar situation, and charge their Volt with no fluid. I'm guessing the motivation for Chevy installing that sensor was seeing others in my situation, and charging their Volt with no fluid, creating issues, possibly dangerous issues.

Yeah, sometimes lawyers make manufacturers do stuff, but most of the time, necessity and common sense rule judgement and decisions.

I'm an Engineer with years and years of experience working in the automotive industry, including manufacturing, software diagnostics, and aftermarket. I've seen it all over that time.

But hey, do what you want.
Are you driving a Gen 2 Volt?

I have no problem with getting a low coolant warning, or with the vehicle shutting down due to these conditions. My problem is with what happens afterwards. So to be clear, this refers to the Gen 1 Volt. More specifically the part that I think was Draconian, was to lock out the vehicle and require reprogramming of a couple of modules by the dealer to resume driving. If I were programming it, I would have warned the driver, and stopped operation, but as soon as the fluid was restored to the proper level, reset the warning, and reset the lockout (or at the very most required the codes to be cleared via ODBII) because with fluid restored to the reservoir the requirements have been met to continue driving or charging. The vehicle already has temperature sensors in the battery pack and will shutdown and lockout if the pack goes over or under temp. The coolant level detection is a redundant component to temperature safety of the batteries. If the illogic of the handling of this seems like some sort of dip s*** politicians got involved, then maybe they did ...
 

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Discussion Starter #18
It is a 2014 Gen 1 Volt.

Yeah, it would be nice if that sensor and detection alert system was more like the windshield washer reservoir sensor. You could simply check for and repair any leaks, fill the reservoir back up, the dash light would go away, and you are all set.

But this is a very different scenario. Chevy makes it difficult to work on and reset for a reason. It is safety-related. Just look at the lock-device on the cap for the reservoir. It makes it much more challenging to even fill this reservoir. A way for Chevy to say "The typical person shouldn't be working of this system, as it is much more important/safety-critical than other systems."

I've seen this type thing on other manufactures as well. For example, to simply release the calipers to install new brake pads on some Mercedes-Benz cars, you actually have to write a specific 300+ byte string to the module that controls the brakes in order for the calipers to release enough to install new brake pads. They don't want these safety-critical things being done by just anybody. You may say to yourself "this is just a way for a manufacturer to ensure that only they can work on their own cars and make more $$$" but notice they don't put this procedure on all repair/maintenance items. You may say "it is so easy to replace brake pads" but believe me, not everybody that performs this task is up to the job, and screws up a very important safety-related thing on a car.
 

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For example, to simply release the calipers to install new brake pads on some Mercedes-Benz cars, you actually have to write a specific 300+ byte string to the module that controls the brakes in order for the calipers to release enough to install new brake pads. They don't want these safety-critical things being done by just anybody. You may say to yourself "this is just a way for a manufacturer to ensure that only they can work on their own cars and make more $$$" but notice they don't put this procedure on all repair/maintenance items. You may say "it is so easy to replace brake pads" but believe me, not everybody that performs this task is up to the job, and screws up a very important safety-related thing on a car.
Yes. Recently I was watching one of Scotty Kilmer's videos where someone asked about some of the strangest repairs he had seen in the shop. He said one was a brake problem and what he found was whoever replaced the brake pads had installed them backwards! They had the metal backing plates up against the rotors!! So I can understand M-B's justification. Some DIY'ers should let somebody else do it.
 

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Chevy makes it difficult to work on and reset for a reason. It is safety-related. Just look at the lock-device on the cap for the reservoir. It makes it much more challenging to even fill this reservoir. A way for Chevy to say "The typical person shouldn't be working of this system, as it is much more important/safety-critical than other systems."

The lock device is so uneducated people don't put the wrong fluid in the battery coolant reservoir.

Some think that water, purified water, soda water, and distilled water are all the same as deionized water for example. They think you can just top off a low battery coolant tank with anything that has the word "water" in it. They would be wrong. So Chevy made it harder for them to do something stupid.


Regarding the sensor defeat,
it "mimics" a properly operating sensor at the correct coolant level, PERMANENTLY mitigating the possibility of ever getting the dreaded SERVICE HIGH VOLTAGE CHARGING SYSTEM (SHVCS) message.

Unfortunately, it's likely not a matter of IF but WHEN as these level sensors have been failing left and right (IMO due to a combination of temperature and vibration) and currently there's no plans to redesign the sensor. (apparently content on letting the dealers replace the sensors in some cases almost bi-annually! lol) LOTS of documented cases in our main SHVCS thread here: https://gm-volt.com/forum/showthrea...ice-High-Voltage-Charging-System-quot-Message

The only real caveat in using the WOT's Coolant Level Sensor (SHVCS Defeat Plug) is that the owner must visually check their battery coolant level at least monthly (as outlined in the owner's manual) just as car owners have been doing for over 100 years! lol

Additionally, there's no real concern that using this device could result in a battery overheat issue as those are completely different DTCs (based on the battery temp sensors) and all have fail-safe behavior that utilizes "reduced propulsion power" to protect the battery even if there's zero coolant (keep in mind on many EVs, such as the Nissan Leaf, coolant isn't even used to cool the battery).

This device will not affect your warranty as it is an "aftermarket replacement part" as stipulated under the Magnuson Moss Act.
 
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