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2012 Service High Voltage Charging System with WOT's Sensor Defeat Plug in place ????

29832 Views 55 Replies 23 Participants Last post by  Rollmann
Kudos to WOT for developing his battery coolant level reservoir sensor replacement/defeat plug. This device essentially mimics the electrical characteristics of a properly functioning OEM coolant reservoir sensor. The stock/OEM sensor is a cheap and flakydevice that can and does fail, causing the setting of fault codes that require dealer level tools to clear the codes.

My early 2012 developed the Service High Voltage Charging System error message months after having installed the WOT sensor replacement. This occurred after a successful recharge while still connected. I scanned for the DTC fault codes with a tablet running the Torque app. Initially the codes were B2AAA, P0AA6, P003E, P1FFF, P1FFF. I tried to clear the codes with the Torque app but as WOT has previously posted only dealer level tools can clear all these codes. The clearing process is in fact a reflashing of the software for the HPCM2 module. After my attempt at code clearing another scan reported P0AA6, P1E00, P1FFF.

I could not charge the battery with either my L2 charger or the stock L1. I uninstalled the WOT defeat plug and reinstalled the original stock sensor prior to bringing the Volt to my original new selling dealer service department. All recalls and servicing have been performed by this dealership. The dealer's diagnosis/repair efforts stopped at square one when they discovered that their Fluke 1587 multimeter was missing and was a required tool in the GM diagnostic procedure. Surprising to me was that the next closest Chevrolet Volt dealer also did not have the required instrument. I guess this is a reflection of how few Volts they service. I had to travel to a dealer a hour away who had the required tool.

I was thinking that there must be some real failure, separate from the reservoir coolant sensor issue, that was casing the faults. Possibly a harness issue as a result of poor workmanship when the battery compartment structural enhancement recall was done a couple of years ago. I had asked the dealer service writer to have the tech perform a reflash of the HPCM2 and Battery Energy Control Module to clear the latching error codes as a first step to see if the faults would then reappear. They refused saying that they needed to follow the documented GM diagnostic protocol steps.

They called a day later to report the Volt was now repaired with nothing other than module reprogramming. The notes on the invoice are:
"Scanned for P0AA6 and P1FFF. Isolation test resistance 250K. Bulletin PIC59206 requires to check coolant level, check moisture in battery as well inspect plugs. No issues found. 2880268 reprogram HPCM2 and BECM"
"The HPCM2 is up to date but not BECM. Programmed BECM and tested resistance. Now at correct specs 3000K. All OK at this time. Programmed CD0D3."

I am glad the Service High Voltage Charging System error message is now gone and I will be able to recharge the battery. But, all of the above is a bit baffling to me. With the WOT coolant sensor defeat plug in place for months without issue and the coolant level at the revised proper level, what triggered the error codes? How could reflashing/reprograming the HPCM2 and BECM cause the isolation resistance measured with the Fluke 1587 multimeter to change form an apparently to low 250K to a proper 3000K? This sound illogical to me. And what is the CD0D3 that was reprogrammed, and what does it have to do with the fault? I cannot find anything about the CD0D3.

Should I know reinstall the WOT sensor coolant defeat plug or leave the apparently correctly functioning coolant reservoir sensor in place?

WOT, if you see this post I would appreciate your take on this and guidance.
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I found part of schematics on German forum it can be seen that connection is on X1 32 33. If I am correct 33 is ground, you can check on conenctor at sensor if ground is ok. here: .opel-ampera-forum.de/viewtopic.php?f=34&t=1830&hilit=f%C3%BCllstand&start=230
I am not able to post image or whole link as i am new here. just add triple w before
Let us know how it goes.
 

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I found part of schematics on German forum it can be seen that connection is on X1 32 33. If I am correct 33 is ground, you can check on conenctor at sensor if ground is ok. here: .opel-ampera-forum.de/viewtopic.php?f=34&t=1830&hilit=f%C3%BCllstand&start=230
I am not able to post image or whole link as i am new here. just add triple w before
Let us know how it goes.
Thank you. Here it is for anyone that finds it useful:

Text Floor plan Diagram Circuit component Line


 

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I found on German forum that there should be 5V on sensor. You can measure that as first thing, so you can se if harness is ok. On page 36 of the forum thread I sent before, you even have instructions that you can redoo what was originally done when sensor was added. as I can see, sensors were faulty because of bad soldering inside of them, so having a spare one instead of just WOT resistor is not bad and price is low. And newer should be without this bad soldering fault. Some reported of dead HPCM2, but this would probably make car dead.
 

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I found on German forum that there should be 5V on sensor. You can measure that as first thing, so you can se if harness is ok. On page 36 of the forum thread I sent before, you even have instructions that you can redoo what was originally done when sensor was added. as I can see, sensors were faulty because of bad soldering inside of them, so having a spare one instead of just WOT resistor is not bad and price is low. And newer should be without this bad soldering fault. Some reported of dead HPCM2, but this would probably make car dead.
Will give it a try on the weekend and report back. I appreciate your assistance, specially because I have no dealer to go to, my Volt is the only one in the entire country, only EV actually. I have PV system and got myself the Volt so I could charge it with solar power, but haven't been able due to this problem.

Here is the larger schematic:

[iurl="http://gm-volt.com/forum/attachment.php?attachmentid=145994&stc=1&d=1516141763"]
[/iurl]

 

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I found part of schematics on German forum it can be seen that connection is on X1 32 33. If I am correct 33 is ground, you can check on conenctor at sensor if ground is ok. here: .opel-ampera-forum.de/viewtopic.php?f=34&t=1830&hilit=f%C3%BCllstand&start=230
I am not able to post image or whole link as i am new here. just add triple w before
Let us know how it goes.
I'm checkin the Service Manual for 2012 Volt, HPCM X1 connector, PIN 32 is labeled AC Refrigerant High Temperature Sensor Signal, circuit 732, Color: WH/L-BU and PIN 33 is labeled Low Reference, circuit 452, Color: BK/VT. According to diagram you shared, PIN 32 is circuit 68, Color: L-BU/YE and PIN 33 is circuit 476, Color: BK/L-GN. It might be possible it corresponds to a different year model or Ampera has a different schematics. Nevertheless, I'll try to verify correct PINs during the weekend.

Again thanks for your help.
 

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Just wanted to report I got it done over the weekend. I updated the Battery Energy Control Module as reported by OP and the latched DTCs didn't come back. Guess an updated Hybrid Powertrain Control Module 2 (HPCM2) without updating the BECM results in a conflict issuing the latched Service High Voltage Charging System DTCs.

Since I had paid for the ACDelco subscription I went ahead and updated other modules as well: Battery Charger Control Module, Body Control Module, Coolant Heater Control Module, Engine Control Module and Electric Power Steering Control Module.

Will write up everything at a later date for others to benefit from my research and experience solving this issue.

Thanks for everyone that helped.
 

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Reviewed my chevy dealer paperwork......seems to suggest my "service high energy system" message is related to intermittent battery coolant sensor (they found no leaks and coolant level was fine). I ordered the defeat plug a couple of weeks ago. Decided to install today. I'll sleep better tonight! :)
 

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Good news, now there's a two year subscription for Vehicle Programming Software. It includes: 24 months access to program all modules for one vehicle (VIN) for $40. Too bad this wasn't available when I did mine, I even had to pay twice since I didn't get it the first time ($55 x 2).
 

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Hi Guys,

Here's a question for you - which of the two connectors in the HPCM2 has the pins 32 and 33 that we were after? Is it the one that plugs into the blue gasket type part, or the grey? I'm referencing this photo: http://www.mediafire.com/convkey/6499/ar0ko1vbavf9phzzg.jpg?size_id=7

I think it's the one connected to the blue gasket type part. Looking at the service manual, I can find the connector with pins 32 and 33 described
32 - A/C Refrigerant High Temperature Sensor Signal - colour WH/L-BU
33 - Low Reference - colors BK/VT.
The description for the connector is '80-Way F MX123 Series, Sealed (BK with BU Terminal Position Assurance Lock).' I think 'BU Terminal Position Assurance Lock' is to indicate that colour of the gasket type part is blue. The other connector's description has 'GY Terminal Position Assurance Lock' which to me indicates it's gasket type part's colour is grey.

I'm waiting for a vcx nano so I can clear the codes, but in the meantime if I could wire the defeat plug close, I can rule out other wiring problems. In the meantime I figured I'd post this to see if my understanding is correct.

Thanks all.
 

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Here's an update so far:
I inspected the car and was able to access and remove the HPCM2 module, but I decided against cutting into anything thus far because that wiring looks quite good... I checked the sensor leads with a meter, and moved the line around the crimped part but didn't see any deviation from 4.99V. What I did find, were some dents under a small metal panel on the right side. That was taken off to look at what it covered, but no signs of damage were found on the smaller metal pipes underneath. I'm assuming these are high voltage wires but I don't know.
In parallel, I have the vcx nano on the way. I bought the 40$ subscription, and when I look at it, I have 3 options:
Vehicle 1
More...
Add VIN (button)

When I click 'Vehicle' it takes me to the pages where I can access SPS but it keeps saying activeX has been blocked. I did as it said and added it to my browser trusted sites, but it keeps saying this. I think this is a warning message at this point. Using 'More' lists the subscriptions and says that the VIN is 'available' - which leads me to a question. Can I set this now or will it get set when I do my first program? I can't find an option to set it now, but I thought I was supposed to do this. If they sell a subscription for just one VIN, shouldn't it be us who enters that VIN number? Anyhow, not sure... if anyone can advise that's great, if not I'll see what happens when I get the programmer... I'm paranoid of some java error or something getting in the way...

Add VIN takes me to the same workflow where I can purchase another VIN number.

Just wanted to update about this in case anyone can advise.

Thanks.
 

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Here's an update so far:
I inspected the car and was able to access and remove the HPCM2 module, but I decided against cutting into anything thus far because that wiring looks quite good... I checked the sensor leads with a meter, and moved the line around the crimped part but didn't see any deviation from 4.99V. What I did find, were some dents under a small metal panel on the right side. That was taken off to look at what it covered, but no signs of damage were found on the smaller metal pipes underneath. I'm assuming these are high voltage wires but I don't know.
In parallel, I have the vcx nano on the way. I bought the 40$ subscription, and when I look at it, I have 3 options:
Vehicle 1
More...
Add VIN (button)

When I click 'Vehicle' it takes me to the pages where I can access SPS but it keeps saying activeX has been blocked. I did as it said and added it to my browser trusted sites, but it keeps saying this. I think this is a warning message at this point. Using 'More' lists the subscriptions and says that the VIN is 'available' - which leads me to a question. Can I set this now or will it get set when I do my first program? I can't find an option to set it now, but I thought I was supposed to do this. If they sell a subscription for just one VIN, shouldn't it be us who enters that VIN number? Anyhow, not sure... if anyone can advise that's great, if not I'll see what happens when I get the programmer... I'm paranoid of some java error or something getting in the way...

Add VIN takes me to the same workflow where I can purchase another VIN number.

Just wanted to update about this in case anyone can advise.

Thanks.
If you have it connected properly the vin will populate for you one the java program starts and you begin. See my other post where you asked the question.
 

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This just happened to me. I installed the defeat plug and reflashed my Hybrid Powertrain Control module (HPCM2) and my code went away. The next day it's back! How did you end up fixing this? Wiring it directly to the HPCM2 or something with the BECM?
 

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This just happened to me. I installed the defeat plug and reflashed my Hybrid Powertrain Control module (HPCM2) and my code went away. The next day it's back! How did you end up fixing this? Wiring it directly to the HPCM2 or something with the BECM?
I ended up not re-wiring anything. After I reprogrammed it with the vcx nano, the problem did not re-occur. I have not however, let it charge for days on end, like I did when I saw the problem. Did your SHVCS message appear when you were driving or after charging? If the latter, one point of interest may be how long of a charge time reproduces the problem.

One other data point for me was that I had some damage on one of the bottom shields (don't ask me which one, IDK, just a flat grey metal shielding a little way back from the passenger side) which I straightened out.
 

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I have not however, let it charge for days on end, like I did when I saw the problem.
The car has no issue being left plugged in for days. If yours faults in that scenario, there is a problem.
 

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The car has no issue being left plugged in for days. If yours faults in that scenario, there is a problem.
Yes, there could still be a problem I just haven't reproduced. I honestly can't think of why a 2-3 day period of being plugged in would provoke something an 8 hour charge wouldn't. An 8 hour charge would be the phase where there's more current, which is where problems would become apparent, or so I would think. The 2-3 days sitting around on the charger is a common element I had when the SHVCS message appeared so I took note.
 
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