[Barry]

So I have the P1E00, P0AA6, and P1FFF codes and SHVCS warning. Battery coolant level is at the bottom of the black label (not top, but pretty far above the seam), so I’m guessing guessing it’s the sensor. I’ve purchased the Canbus SHVCS Defeater plug and the VCX Nano. I’ve read all the instructions and everything seems pretty straight forward. However... the instructions say I need to clear the codes before installing the defeater plug. Wouldn’t they just come right back on if I did it in that order? Wouldn’t it make more sense to first plug in the defeater plug, then clear the codes out?

What you are saying is logical. I think the instructions assume you would get the codes cleared by the dealership, in which case you would not want the defeat plug installed for that, because it would disrupt their troubleshooting steps and cause them to blame your aftermarket part for the trouble. But if you are clearing the codes yourself, then doing it after installing the defeat plug seems like a sensible approach.

 

[jbakerjonathan]

Why not clear the codes first? Then, disconnect the 12V battery, and finally install the bypass plug. Re-connect the battery and you should be good to go. AFAIK the codes would only come back if you were to power up the car and/or drive it. What year is it? The 2011/2012 models were re-wired for the sensor by the dealerships under a recall program. Some dealers didn't do a very good job splicing the wires and the harness gets corrosion which will set the codes. The defeat plug will not help in that situation.

To correct your post slightly, GM completed the engineering of the additional sensor during the 2012 model manufacturing cycle. Some of the late 2012s came out of the factory with the additional sensor factory wired in. At least, that is how I remember it.

 

[TheYonderGod]

This link is really great, jbakerjonathan, thank you for posting. Barry, I agree that's good it appears to be accessible. They mention wiggling the coolant tank out of the way, but I'm hoping I wouldn't have to do that. Hopefully I just have to redo some splicing within easy reach.

Here's one question that is probably obvious to everyone but me: Did they cut out the refrigerant sensor right out of the system and never connect it again? I'm looking at page 16, figure 10.6. This is how I understand what they've done with this line:

1 - the refrigerant sensor line is cut
2 - the battery coolant tank sensor wires get crimped onto this line
3 - the original end of this line which connected to the refrigerant sensor contacts is discarded
4 - they cover up the refrigerant sensor contacts so they won't corrode now that there isn't any connector on them (page 19)
5 - they connect this line which now has the coolant tank sensor on the end, to the white housing under the coolant tank
6 - the programming update makes it ignore the fact this refrigerant sensor is no longer connected, and instead consider the signal on that line to be from the battery coolant tank

Does that sound remotely close?

Thanks guys for your help so far.

When updating the calibration on HPCM2 with SPS on a 2012 (and presumably 2011), you are asked during the update process if the car has the updated coolant reservoir (it actually references the bulletin/recall number). There is even a picture telling the tech to look for the locking ring on the reservoir.

If the car never had the recall performed, then a different calibration is flashed. So, presumably GM has been maintaining parallel code trains. I've actually been curious if flashing the recall-not-performed calibration would just disable the coolant sensor.

This was posted a long time ago and maybe I'm just late to the party, but has anyone considered reattaching the refrigerant sensor and reflashing, selecting no reservoir update. Seems much more simple?

 

[Tacoma]

This was posted a long time ago and maybe I'm just late to the party, but has anyone considered reattaching the refrigerant sensor and reflashing, selecting no reservoir update. Seems much more simple?

I would be interested in seeing how this is done. Can you post pics and details of doing this?

 

[TheYonderGod]

This was posted a long time ago and maybe I'm just late to the party, but has anyone considered reattaching the refrigerant sensor and reflashing, selecting no reservoir update. Seems much more simple?

I would be interested in seeing how this is done. Can you post pics and details of doing this?

I'm just theorizing, asking if it makes sense to anyone else or if I'm overlooking something. Definitely not suggesting anyone do it at this time.
Has anyone even tried just selecting 'no-update' without changing any wiring?

 

[stup70]

Hi

I'm in the UK, just got the SHVCS code(s) on my 2012 Ampera. Is the defeat plug still available for purchase? Thanks.

 

[Btravelen]

https://canbustools.com/products/chevy-volt-2011-2015-shvcs-defeat-plug

Sent from my LM-V405 using Tapatalk

 

[stup70]

Thanks, yes I saw that page. There's no contact details at all shown and thought it a bit iffy just making payment to an unknown source. Have you dealt with the site?

 

[Btravelen]

Yup. Good guys. Great product and quick shipping.

Sent from my LM-V405 using Tapatalk

 

[stup70]

Great, thanks for that.

 

[Btravelen]

[email protected] is the contact email if you care to ask them about it.

Sent from my LM-V405 using Tapatalk

 

[stup70]

Thanks will give it a try.

 

[stup70]

Made my own defeat plug and used ODB2 but can't clear the codes which are latched. I have a VCX Nano which I connected and used GDS2 which also didn't clear the codes so I'll have to reprogram the HPCM2 module. It seems the ACDelco page has changed as it now says it doesn't support Vauxhall/Opel programming which may be a problem for my 2012 Ampera
So a couple of questions -
1. Would the Chevy Volt s/w programming be ok for the Ampera
2.If so what do I select on the ACDelco page for SPS programming - is it the SPS prog 2 Hours 35.00 €?

 

[Alkers]

Does anyone have the part number for the faulty sensor which causes this error in the first place?
I have the SHVCS error currently and the only dealer is 2+ hours drive. I want them to clear the codes and replace the sensor so that the error doesn't return before I get home again to install the defeat. Does this make sense or does the dealer clearing the codes keep the car error free for a while even with the original sensor in place?

 

[dvancleve]

Howdy folks. I read through a lot of this, but I obviously not all of it. I have the SHVCS error now, with no leaks that I’ve seen and a full coolant reservoir. I took it into one of two recommended Chevy dealers, thinking it was probably going to be $300 or less. I’ve been quoted $733, which I gather is completely replacing the reservoir because they say “the float is sticking“. There is no way I can install this bypass and skip this repair? I’d really like to not spend that money… Thanks, Doug

 

[BillG]

Howdy folks. I read through a lot of this, but I obviously not all of it. I have the SHVCS error now, with no leaks that I’ve seen and a full coolant reservoir. I took it into one of two recommended Chevy dealers, thinking it was probably going to be $300 or less. I’ve been quoted $733, which I gather is completely replacing the reservoir because they say “the float is sticking“. There is no way I can install this bypass and skip this repair? I’d really like to not spend that money… Thanks, Doug

There's a recall program which reprograms the battery control module and which will clear these codes. This a a N/C fix, which I just had done while flushing the three coolant systems. I had been dealing with the SHVCS error for about 6 months, clearing it with the Torque app and recharging the battery, but the error codes would come back. Bythe way, I had the WOT bypass lug installed, but removed it before taking it in. I have not reinstalled it yet.

I don't know if this will fix your problem, but if your car hasn't had the rebalancing fix applied, I would ask them to try that first.

 

[BillG]

"WOT bypass lug"

That should read "WOT bypass plug". Where is the "edit" button??

 

[dvancleve]

I don't know if this will fix your problem, but if your car hasn't had the rebalancing fix applied, I would ask them to try that first.

Thanks BillG

The previous owners of my car were very diligent, I am certain it has had all the patches/fixes applied to it. I think the float probably is stuck in the reservoir, my issue is that the switch bypass would fix that as well (wouldn’t it?). I don’t know why I didn’t call him first, but a mechanic that worked on my Prius a bunch and told me he also worked on Volts said he could fix this and definitely for less than $733. My current plan is to have the Chevy dealer reset all the codes, pay the one hour diagnostic fee and drive the car home. If the code doesn’t come back right away, I’ll let the car sit until the bypass switch arrives and install it myself. If the code comes back, I’ll take it into my independent shop, have him reset the codes and install the bypass switch. Replacing the whole reservoir for that kind of money is bonkers if I can avoid it...

Doug

 

[JuneBug]

Thanks BillG

The previous owners of my car were very diligent, I am certain it has had all the patches/fixes applied to it. I think the float probably is stuck in the reservoir, my issue is that the switch bypass would fix that as well (wouldn’t it?). I don’t know why I didn’t call him first, but a mechanic that worked on my Prius a bunch and told me he also worked on Volts said he could fix this and definitely for less than $733. My current plan is to have the Chevy dealer reset all the codes, pay the one hour diagnostic fee and drive the car home. If the code doesn’t come back right away, I’ll let the car sit until the bypass switch arrives and install it myself. If the code comes back, I’ll take it into my independent shop, have him reset the codes and install the bypass switch. Replacing the whole reservoir for that kind of money is bonkers if I can avoid it...

Doug

Go to this site and order the plug:

Chevy Volt 2011-2015 SHVCS Defeat Plug

In Stock. Product normally ships within 24-48 hours. We are shipping during covid. Supported for Chevy Volt 2011-2015 models (Service High Voltage Charging System) issues from poorly designed GM battery coolant sensor or retrofit models (2011-2012). Compatibility 2011-2015 Chevy Volt...

canbustools.com

I did it and it's very well made and easy to install.

 

[Steverino]

Thanks BillG

I think the float probably is stuck in the reservoir,

Doug

?? None of the fluid reservoir tanks in my 2011 Volt or my 2017 Bolt have a float that I have seen. For sure the battery coolant reservoirs do not.