Vehicle: GM Volt 2012 or other Gen1 models
I experience the “reduced propulsion power (PPP)” message if I make a stop after switching to the ice on my way home.
The message that required the update was “service high voltage charging system”. The range change was instant, immediately following the update。
To enable hardware replacement, the Hybrid Powertrain Control Module 2 can be placed into a fast learn mode with the scan tool.
Here is the fix for this problem. ( Gen 1 Volt )
Purchase a used HPCM2 module from Ebay or an auto wrecker the same year as your Volt.
You can use another year Volt providing the used HPCM2 module has the same part number as stamped on your existing HPCM2 module label.
Next, purchase a vxdiag vcx nano programmer from the following web site:
Download the free software to run the VXDiag programmer into your laptop running Windows.
Disconnect your 12 volt battery, ( in the trunk compartment ) and swap in the used HPCM2 module ( module is located under the passenger front seat ) it is easier to remove the 2 torx bolts and lift the seat out of the way to swap the HCPM2 module out.
Reconnect the 12 volt battery. Power up your Volt. Next plug in the VXDiag programmer into your OBD2 port ( under the steering wheel ), run the downloaded program ( from VXDIAGSHOP website ) and “reset” the HCPM2 module in the menu. ( You need to scroll down the various menus to find this “reset” option )
Once you reset the HCPM2 module, turn the Volt off and back on again. Now charge your Volt. Your battery range will come back to the original 10.3kwh ( or whatever it was before the GM dealership HPCM2 firmware update ) per full charge range.
This method works 100% because I successfully performed this on my 2012 Chevy Volt car after a GM dealership reprogrammed my HCPM2 module and subsequently I lost 1.2kwh per full charge. ( 9.1kwh )