stay open to the idea of a reprogramming of the HPCM2 and/or BMS and relearning of the cells and capacity.
If you could explain to me how this works I'd appreciate it. Is this something that I can do with the VX-NANO? I'm still learning how chevy works compared to my 500e.
I found a volt owner that had the same problem, he ran a isolation test to get the car charging. How do I run an isolation test on SPS2?
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Ok so I got the nano to work and I am connected to the spark in SPS2. What module would I have to reprogram to get the car charging?
Update. Didn't have to do the test. Just reprogrammed the HPCM2 and then plugged it in. The car is now charging. I'll check on it after work to see if the 2 weak cells balance or if they are damaged.
First of all, congratulations on unbricking your Spark EV. You powered through all the uncertainty and familiarized yourself with the VCX nano.
To answer your first and second posts, there are procedures to reprogram the BMS and relearn cells, it should be detailed to some extent in the service manual. There are also functional commands as you've noted, including isolation testing.
Chelmu, the Chevy Volt owner in the example you gave got lucky essentially pushing buttons as a last-ditch effort and hoping for the best. What he had in common with you is that he has a Chevy Volt that uses the exact same parts as the Spark EV, save for having the extra engine/generator hybrid parts.. You both also received a set of no-start condition codes, P1E00 and P0AFA for the HPCM2. These codes are "serious" codes that will put the high voltage pack in lockout, preventing all charging and discharging activities.
Chelmu initiated an isolation test. I'm not versed on the specific sequences of this test, and nobody besides GM and maybe Dr John Kelly at Weber University would understand the various sequences it goes through. During this test, the controller determined isolation was sound after looking at voltages in key areas and proceeded to look up specific secured/permanent DTCs to clear, one or both P1E00 and P0AFA were on that list. Once Chelmu crossed their fingers and started the car, more tests were conducted during startup, and the HPCM2 released its lockout of the high voltage systems.
Actually Prof. John Kelly does have a video on this at the 32:08 mark.
Here he uses GDS2 to clear high-voltage DTCs and then proceeds to run an isolation test:
It's Always Something DIY demonstrates fixing a no-start DTC from P1FFE caused by low battery coolant, or sudden bumps causing sloshing that would unsettle the float magnet inside for long enough. He resolves this by simply doing a Secured DTC Clear.
He made a second video where he used an AC Delco TDS subscription to gain access to module reprogramming and reprogrammed the HPCM2 to clear Secured DTC errors for "Service High Voltage Charging System"
So how come reprogramming lifts a lockout as others have demonstrated online?
My understanding is the HPCM2 stores, tests, and manages all the high-voltage trouble codes by querying all the modules and their sensors through GMLAN communication. If you reprogram the HPCM2, you wipe its memory until trouble is reported to it again. This happens while driving, and isolation is always tested after contactors open. The one flaw with this system is there is no way for the HPCM2 to test if isolation recovers after time because it locks out the high-voltage system and battery pack. High voltage is scary and dangerous but not having a vehicle to rely on is just as dangerous and damning, these systems don't account for intermittent issues and glitches. I'm sure you'd object and say it's to prevent a failed isolation test from causing a battery fire or electrocuting someone, but to that, I would simply say the 2017-2020 Bolt EV recall catastrophe demonstrated there are far larger risks out of the system's control, nobody who has owned an OEM EV has ever been electrocuted, and more importantly, GM has an economic model that is designed to generate revenue on malfunctioning vehicles, and brick them for that revenue.
I will say that just because you lifted the lockout doesn't mean this couldn't happen again as you are understandably wary of the previously unbalanced or degraded cells. They may generate a code in the same way, and that's where babying it under 20% could come in consideration. That being said, a loss of isolation by moisture ingress could brick your spark in the same way, as well as geomagnetic ion storms, solar flares, high energy cosmic rays, etc (space weather), and of course, real component failure. It's worth it to monitor the cells as you have been doing over the next several charges to see how the system is behaving. Keep your VCX Nano and a laptop nearby in case you get stranded too.
100PercentJake recently tried to unbrick their Spark EV from an auction and decided to drop the battery and replace the BECM and try to re-learn the cells instead of the HPCM2. They encountered an error and believed they fried the BECM. However, there was no solid evidence to suggest the BECM was fried, and they simply were dealing with a HPCM2 issue like most everyone else.
Good for you for doing your due diligence.