Well, only a few days later I'm back with a new problem.
The car was finally charging and driving fine, but two days ago my dad thought about using the radio on accessory mode until the car shut itself down, right after charging the HV battery to 100% and unplugging the car... then yesterday we tried to turn it on and the EV system warning plus the turtle mode lights turned on, as well as the red low 12V battery light... I thought immediately about plugging it to charge, but there was no beep, no dashboard lights, no green "plugged in" light, nothing, just the "flick" sound that something makes inside the port after plugging it in.
I tried rebooting the car several times, by disconnecting the 12V battery and connecting it back after several minutes, as per the usual method. But the EV system warning and turtle lights won't go away, and the car won't charge.
LeafSpy keeps showing 2 errors only: P3196 and U1000, specifically as follows:
>P3196-00 0B EV/HEV CAN Error EVC-274
>U1000-00 0B EV/HEV Can Comm Circuit
U1000-00 4E HV BATTERY CAN Comm Circuit
P3196-00 4E HV BATTERY CAN Error EVB-99
They cannot be cleared, even after repeated reboots.
I checked P3196 on the service manual, and it seems to be directly related to low 12V voltage. It says:
"When VCM detects an error signal that is received from PDM (Power Delivery Module) via CAN communication" and "Make sure that 12V battery voltage is 11 V or more."
Otherwise, if it's not that, it could be the PDM or VCM, according to the manual.
So I checked the 12V battery with a multimeter and it was falling from just over 12V to 11.6V when the car was turned on. Also, it was clearly not charging. As you know, this battery was already previously deeply discharged for a long time, then just the day before it was discharged as well. Then we know that the Leaf's 12v battery charging system isn't that good. So I took it again to Autozone to recharge. I couldn't get it replaced by warranty as they seem to have mistyped my phone number when I bought it.
Well, today I took the battery home, which according to them had been charged to 13.38V at that moment. As you can tell it wasn't topped to 14V or more. I installed it on the car, and nothing. The EV warning and turtle lights are still there. There still doesn't seem to be any reaction from the car when the charging cable is plugged in. I retried deleting codes with LeafSpy, rebooting many times, even using my other Leaf's known-good battery on the problematic car (that one actually showed less voltage on the multimeter than the bad battery), but nothing changed.
I tried requesting ECU versions via LeafSpy and to my surprise "CHARGER" does not show up anymore. Due to this, and the fact that there's absolutely no reaction from the car to plugging in the charger, except for that "flick" sound, it seems that there's an actual lack of power, or at least very important communication to the PDM.
I really don't think the PDM is dead again, as it had been charging fine just before that, the error did not show up immediately after charging, and my EVSE is well-protected against power surges. Plus, when it actually dies, it tends to be detected by the VCM, there are beeps when the charger is connected, but electrical problems are detected inside the PDM and charging is prohibited. But, what could it be then?
Is there any fuse or relay I could check? Maybe the PDM harness has a faulty connection with intermittent issues? Is the whole car so sensible to low 12V power that now I need a brand new battery charged up to 14V to get the PDM to work? But if so, then how does my other Leaf work perfectly with seemingly less voltage? Maybe something triggered somewhere and needs to be reset physically?
The case is open again. Any help will be appreciated.