Reprogramming 2012 Chevy Volt HPCM2 with VXDIAG VCX Nano

I recently decided to fix an issue on my 2012 Chevy Volt: a bogus code about low coolant in the high-voltage battery coolant reservoir. It doesn’t happen often—maybe once a year or once every six months—but it’s really annoying when it does. I’ve tried a few quick fixes, like hardwiring the resistor, cleaning and re-soldering the sensor leads, but it still trips the code from time to time. When it happens, I need to reprogram the HPCM2 (Hybrid Powertrain Control Module 2). I got tired of taking it to the dealership every time, so I decided to give the VXDIAG VCX Nano a try and here’s how it went.

I used a Windows 10 computer for the process (Windows 11 should work too, but I didn’t test it). I ordered the VCX Nano from vxdiag offcial web, downloaded the latest VX Manager software, and followed these steps:

1. When installing VX Manager, I checked the J2534 Passthru driver box, NOT the manufacturer-specific ones, and definitely NOT the GM ones.
2. I went to acdelcotds.com, created an account, and purchased the $45 1-VIN software subscription for 2 years.
3. After buying the subscription, I went back to the subscriptions page, logged in (you have to log in every time, which is a bit annoying), and clicked the "Add VIN" link to download the Techline Connect installer.
4. I ran the installer, let it finish, and closed Techline Connect. The username and password I created on acdelcotds.com didn’t work for logging into Techline Connect, so I didn’t bother trying.
5. Back at acdelcotds.com, I logged in again, clicked “Add VIN,” and then launched Techline Connect. The software detected that there were a ton of updates it didn’t have, so it went through them all and installed a bunch of new files.
6. Once everything was installed, I ran Techline Connect again, clicked on the SPS option, and selected the VXDIAG device. The VIN was automatically detected and I was able to keep clicking "Next" until I reached the list of modules.
7. I found the Hybrid Powertrain Control Module 2, clicked it, and kept hitting "Next" and agreeing to everything until the process finished.

After programming, if the check engine light is on, you might need to turn the car off and on again to clear it.

The whole process took me around 1 to 2 hours depending on how fast I was. For a pretty reasonable cost, I now have the ability to clear codes, whether it’s a real issue or not.

Updated: I also tried it on Windows 11 and it worked just fine, following the same steps. In about 2-3 hours, I cleared the DTCs, and my Volt was charging again with a green light. I’ve never been so happy to see my Volt charging again.

If you're facing a similar issue, this method might save you a lot of time and money.

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