How to Clear SHVCS Fault Code on a 2012 Chevrolet Volt Using VXDIAG

Model Information: 2012 Chevrolet Volt (European version)

Fault Background:

As a 2012 Chevrolet Volt owner, I've recently encountered an annoying charging issue—SHVCS (High Voltage Cooling System) problem. This issue is a common problem among Volt owners, so I decided to share my solution.

My initial solution was to create a 24.7kΩ virtual load plug, which worked fine for a long time. However, one day, I returned home and plugged in the charger. The vehicle initially started the charging process normally, with the green indicator light on the dashboard, but after five seconds, the green light went off, followed by the SHVCS warning.

My first thought was that the virtual load plug I made had failed. I took the plug out and tested it. The resistance was 24.6kΩ, which was within the normal range. I even used a blow dryer to heat the plug, simulating extreme working conditions, but it still worked fine. So I ruled out the possibility of the plug being the issue.

Later, I realized the problem might lie in the wiring between the coolant sensor and the control module, especially in the K114B module. This 5V line is very sensitive, and even a small contact issue can trigger a fault. To completely solve the issue, I decided to connect the virtual plug near the K114B module to eliminate any interference from the wiring.

Previous Attempts:

The company has a Launch diagnostic device, so I decided to try clearing the fault code using it, hoping to restore the vehicle’s charging function. After checking, I found the following fault codes:

• P0AA6-00: Hybrid Battery/Insulation Loss.
• P1FFF-00: System Isolation/Coolant Sensor Fault, Hybrid Battery Charging Disabled.
• U0140-00: Lost Communication with Body Control Module (likely because I disconnected the 12V battery, which can be ignored).

I attempted to manually clear these fault codes, but while the fault lights briefly disappeared, they quickly came back on, and the issue was not resolved. Later, I noticed that the resistance of the coolant sensor fluctuated abnormally after clearing the fault codes, changing from 0Ω to around 250kΩ, which was clearly not normal.

Someone on a forum suggested that long drives might solve the problem. I tried a 150km family trip, but unfortunately, this didn’t clear the SHVCS fault either.

Final Solution:

After trying various solutions without success, I decided to directly reprogram the K114B module. This is considered the final solution for the SHVCS issue, but it requires the proper equipment and software. Here are the steps I took:

Tools and Preparation:

• VXDIAG VCX Nano GM Cable: Make sure to buy the GM version as it supports necessary programming features for Chevrolet.
• Laptop: The laptop should have a fully charged battery to prevent any accidental power loss during programming. It is best to install a fresh and clean Windows 10 system, ensuring that the system and drivers are updated, with at least 15GB of available storage.
• Network Connection: A stable network connection is required during programming. Ideally, make sure there is WiFi coverage at the parking location or have a mobile hotspot with sufficient data.

Detailed Steps:

1. Install VX Manager: Download and install VX Manager from vxdiagshop.com. During installation, select only the “PASSTHRU - J2534” option. After installation, ensure the cable is properly connected and recognized by the device.
2. ACDelco Account: Go to acdelcotds.com/subscriptions, register an account, and purchase a 1-hour programming access (costs 4 Euros). Ensure you're doing this near the vehicle because the timer will start immediately once access is purchased.
3. Install and Configure Techline Connect: Use the link on the “Service Information (SI), Programming Software (SPS2)” page to download the Techline Connect software. After installation, make sure to launch the software using the TLC tab for successful login.
4. Programming Process:
   • Connect the VXDIAG device to the vehicle's OBD2 port.
   • Start the vehicle and enter service mode (press the start button for 5 seconds without pressing the brake pedal).
   • In Techline Connect, select the K114B Hybrid Control Module (HPCM2) and click “Start Programming.”
   • The programming process will take about two minutes. During this time, the dashboard may display a "Service Anti-Theft System" warning, which is normal. After completing, clear the fault codes and disconnect the device.
5. After Completion: After completing the programming, turn off the vehicle, disconnect the cable, and start the vehicle as usual. The SHVCS fault notification should now be cleared.

Important Notes:

After reprogramming, all charging-related settings will be reset. For example, the vehicle may re-enable the power-down reminder and other settings. Be sure to adjust these settings in the menu to avoid unnecessary alerts.