VXDIAG VCX NANO Clear GM Volt P0AFA Code with TechLine

There is a very specific, multi-step procedure to clear the secure high voltage code using vxdiag vcx nano for gm. It's a little tricky and may take more than one attempt.

I suggest buying a short term subscription to the volt shop manual from GM Techline: Techline Connect Diagnostic System Software | ACDelco. The procedure is described in the CLEAR SECURED HIGH VOLTAGE DTC'S section. If you really want to understand your car, this is the best route.

If you want to try it, here's the procedure:

You will be clearing the secured DTC's from two modules. PCM2 and PCM. You will clear PCM2 twice.

1. Put car in service mode
2. Hook up VX Nano
3. Run GDS2
4. Select vehicle
5. Clear all DTC's
6. Go to modules
7. Select Hybrid/EV Powertrain Control Module 2 (HPCM2) control functions list
8. Select "Clear Secured High Voltage DTC's". Follow the on screen instructions, it won't look like anything is happening, but it is. WAIT AT LEAST 45 SECONDS before exiting back to the menu.
9. Select Hybrid/EV Powertrain Control Module (HPCM, not "2") control functions list.
10. Select "Clear Sceured High Voltage DTC's. Follow the on screen instructions, it won't look like anything is happening, but it is. WAIT AT LEAST 45 SECONDS before exiting back to the menu.
11. Now, go back to the PCM2 module (step 7) and clear secured high voltage dtc's again.
12. Go back and clear all DTC's from the vehicle again
13. Now, the car has to go to sleep to finish clearing the codes
14. Turn the car off.
15. Unplug the VXDIAG VCX Nano
16. Don't touch anything, keep the doors shut (I may have opened and shut the drivers door to speed things along) and wait five minutes.
17. Power up the car and the MIL should be out.

If the MIL is still on, try it again. If it is still on... you may have a problem (or problems) that can't be solved by clearing the secured codes and may have to reprogram HPCM and HPCM2 modules and/or replace hardware.

Oh, and one more thing. Service mode will drain the 12 volt battery fairly quickly. Make sure it is in good shape, fully charged and work fast. If you have a high quality battery charger (a "smart" charger for example) that puts out clean power, use it. You will need at least 10 amps to keep everything happy. If the voltage falls below 12 volts or so, strange things can happen.

Good luck.