Service High Voltage charging system

[tim.moore]

I got this message on my  2012 Chevy Volt.  I humbly offer this mistake to help others I hope.  I  could not charge the car. I searched the message online and found that my coolant level being low caused the message.  I filled the coolant level, but it said I had to get the message cleared.  I learned that O'Reilly and Autozone will not clear the message any more.  I went to Castle Chevy to get it cleared, they said, "the sensor inside the reservoir was no longer working and had to be replaced.  I unfortunately signed off on the work.  Went home to find out that if I drove it for five days it might  reset the computer.  I tried to stop the repair, but because I signed off they immediately did the work.  The cost humbly offer to you to fill your coolant levels.  $1,040 ouch.   

[tim.moore]

One benefit I noticed so far is that the charge range increased from 31 miles to 38 miles.   I wonder if the coolant sensor could have been reducing the charge?

[simon.gibson]

To replace a sensor!!! Wow, is it gold plated shipped direct from Buckingham Palace?
Hence the Right to Repair movement.
Gouging by stealership must STOP now. It's one of the reasons people unnecessarily scrap equipment when a simple repair is the most ecological solution.

[tim.moore]

Yes Simon, I did kick myself for signing off on the repair.  The part was $125 with the labor being over $800, so at least the mechanic got paid, though the dealership probably took most it. Having been a converter of a gas to electric myself, I see again how nice and less expensive it was and I think still is to work on your own conversion.

[ben.schmid]

There is a discussion thread on this topic on the Volt forum.  The coolant sensor is prone to fail, and it then triggers this message.  There is a remedy, with the WOT sensor, which is for sale on the site for about $40.  It functions by removing the ffailure-prone coolant sensor, and replacing it with something that sends a positive signal.  (You have to remove the negative 12 volt battery prior to installing it, so it doesn't trip a message and trigger the SHVCS message again)  Of course you then have to check the coolant level manually, as the sensor is no longer functioning.  I have to confess that I ordered this workaround, but have not yet installed it.  At first I did it because I didn't want dealer technicians noticing it and denying me warranty coverage for other items.  But now that my warranty is expired, I should install it.

[tim.moore]

Thanks Ben.  I forgot that you owe a Volt and a Bolt.  Could send  the link to the Volt forum?  How is your Bolt?  Seems like a good alternative to paying for a Tesla.

[ben.schmid]

The Volt forum is GM-Volt.com.  We enjoy both of our vehicles very much.  I think when comparing the Bolt to Tesla the main Tesla advantage is the network of fast chargers that they have.  This would be good for anyone who makes frequent long trips (approx 3-400 miles or more)..  We don't make that many such long trips.  We can make long trips with careful planning for DC fast charging stops.  The charging speed at DC Fast stations in the Bolt is intermediate, slower than Tesla.  Availability of DC fast stations is improving all the time.  Charging speed is also faster in newer electric vehicles (ex VW ID-4).  So if you get a Bolt make sure it has the capability of DC Fast charging, as this is an option. 

[jeffrey.miller]

https://www.gm-volt.com/threads/wots-coolant-level-sensor-service-high-voltage-charging-system-message-defeat-plug.255506/

Here is a long thread on the topic.  The connector kit Ben described to me came with two parts, a connector that fits into the harness that has some electronic thing (a resistor or capacitor of the correct value I assume) and then a second connector that plugs into the actual sensor to protect it from the elements. 

As Ben described it is a proactive thing, disconnect the battery, and make the change, and don't wait for it to fail because the labor is horrible. 

As far as my experience with the Bolt I like it.  It isn't a Model S, and I wouldn't drive it to Arizona due to it's slow 50KW fast charging, but for all my needs, except vacations, it works perfectly fine.  We use the I-Miev to go to the store or whatever when the Bolt is in use, so I probably drive them about half and half.  For the 24K I spent on the Bolt new and the $2900 I spent on the I-Miev, I really can't complain about what I get.  They are both functional have AC, and work well within what is reasonable for each of them. 

[tim.moore]

Thanks Ben and Jeff, very helpful advise.  My son is the one who might be interested in a used Bolt.  It seems like just yesterday I had him to Triton College for FVEAA meeting and Ted Lowe took him under his wing to think electric.  He is 24 next month, and as he is from South Korea and 55% of  the Bolt was made in South Korea, he is thinking of a used one.