Leaf does not start :(

Good afternoon
My Leaf is naughty, I've been suffering with it for a week and I can't figure it out. The machine does not start, but there are two conditions under which it starts.
1 - The 12v battery is fully charged and shows more than 13v. (Battery installed new)
Yesterday I noticed that even on an old battery that is not charged, it starts up if the car stands for a while.
2 - More than 30 minutes pass between launches.
After starting, the machine runs normally in normal mode, after turning it off again it does not start.
Attached is a photo from Leafspy. Interlock near the BSM connected to the battery, but the error does not disappear!
Maybe someone knows where to dig, already broke his whole head!

Thanks for the help and support friends. Sarcasm

We don't recognize this particular problem and group of error messages. I understand your frustration, but please be polite here.

CAN'T SWITCH ON, BECAUSE ALREADY ON (READY)

This is just my fantasy (I am not an expert) based on the following logic:
When an alternator charges a 12V it puts 13+ volts on the poles of the 12V
An EV uses a DC-DC converter to convert HV to 13+ to put on those poles.
You only will measure 13+ volt on an ICE when it is driving, but a lot of people have been measuring 13+ volts on their Leaf while stationary (while investigating EV System messages). The DC-DC has to get its power from the HV bus and thus is the LI-ion in 'READY' mode.
When switching the car on, it assumes that the status is UN-READY (a dead HV bus, dead DC-DC and thus 12V's 12 volts). I believe that some lines in your DTC refer to HV leaks, I guess it is interpreted as: the HV bus is not dead so there is a leak. And for safety the 'switch on' procedure is aborted.
What your car keeps doing for half an hour after shutting down, I have no idea, but at least it finishes the procedure properly by UN-READY the LI-ion in the end.
In the half hour : can you start charging (SMART and/or Granny) ?
If this fails; is the message 'Already cable connected'?
Can you always start the car if 12 volts is measured just before?
Can you never start the car if 13+ volt is measured just before?

The only other way to switch OFF (into UN-READY) is by stopping to charge. And off course the good old disconnect and connect hardware. Decades ago we had to take the battery out of our phones to reset. This was sooo stupid that now almost all electronic equipment has a reset button/menu option/procedure to HARD SWITCH OFF. It is a shame that the car mechanics at Nissan didn't think it prudent to supply. You would expect the Li -ion to be switched OFF by the system very pro actively. As for example in an accident you would not like 400V Live cables hanging around. But instead we can not even manually switch to UN-READY It is just my fantasy, but in this fantasy some EV system msg survivors have been poking under the bonnet while the 400V is Live and that includes you. So to end on a positive note: you are still alive.

I hope you are healthy and well, so that you are just wilfully not replying.

Can someone please debunk my premise, that:

Anyone who thinks they are working on a 12V battery, which generates 13+ volts , is in fact working on a system where the 13+ volts is supplied by the DC-DC and thus the HV has to be live.

Cheers

Yes, that is basically correct. The 12V battery is nominally at 12.x V and this value will vary a bit based on the state of charge of the battery, the load on it and its temperature. The DC-DC converter charges the 12V battery (and indirectly supplies power for all the 12V systems) while the car is operating, just like the alternator does in an ICE vehicle.

I don't know the exact protocol for when the HV battery is disconnected when the car is powered down but there actually is a physical HV disconnect switch in a Leaf. It is located behind the front seats in the middle of the car under a cover. You can remove the connector to physically break the circuit from the HV battery. This is rarely needed and is designed mainly for maintenance work on the car that is well beyond the scope of normal operation.

As I mentioned, I don't know when the HV battery is disconnected from the DC-DC converter after the car is switched to UNREADY but I do think that if the 12V supply measures 13+ V then the DC-DC converter is supplying that power, either from the HV battery or from its own capacitance storage.

If the 12 volt battery is disconnected when measured, then it can read 13+ volts if fully charged recently. This is especially true of AGM and lithium batteries, although I don't know if they can read over 13 volts while connected and the car is Off.

Good point. I guess I was referring to SLA batteries and forgot about the other types used today. And yes, I guess it could stay above 13V for a while but it should drop down to around 12.7V eventually. I don't know how long that typically takes and it probably varies depending on whatever....but those are the numbers I'm used to.

Thanks for the quick reply. I ignore, for the time being, all of the great info.

If we consider the premise valid, then the interpretation of these 2 sentences in the original post are very scary.

The 12v battery is fully charged and shows more than 13v.

Maybe someone knows where to dig, already broke his whole head!

Cheers

A lot of the errors shown in the OP are related to CAN Bus communication problems and/or low 12V battery voltage. The AGM battery in my 2019 LEAF will drop below 13 volts as soon as the car is turned off because the computers draw power for a short period of time before sleeping. After the computer modules drop into their low power (sleep) states, the battery recovers to between 12.7 and 12.8 volts before dropping very slowly over time. It takes about 3 hours before it drops below 12.7 volts.

Regarding the OP's problem, the DC-DC converter must be on if the 12V battery is above 13 volts (if measured with an accurate meter). The main DC contactor opens when the car is turned off unless something is wrong. The main DC contactor is closed by applying 12V power to its coil and it opens when 12V power to the coil is turned off. The high-voltage battery disconnect described in one of the replies (in the center of the car under a cover in the floor in front of the rear seats) is a manual disconnect used to disable the high-voltage system during maintenance/repair of the EV system.

Yes, live is easy.
When the car is ON (READY) the voltage is >13
When the car is OFF (UNREADY) voltage is <13
Car OFF and still voltage>13 means malfunction.
There should be no current on the HV bus, but there is resulting in P31E1
service manual "
VCM receives the connection malfunction signal via EV system CAN communication sent from Li-ion battery controler
potential causes :
• Harness and connector (Connection detecting circuit within Li-ion battery)
• High voltage harness
• Service plug

Unfortunately these are only hardware causes. The possibility that it is just software is not even considered. Only because the car thinks it is OFF is the current a malfunction else it is simply the DC-DC supply for for the 13 volt. And it is unlikely an hardware problem as each time after half an hour everything is OK.

The scary bit is still that the car is READY and the HV is live, while we think that the car is OFF (and UN-READY)
Is there no more sophisticated way then connecting and disconnecting hardware to reset a piece of electronics?

“Anyone who thinks they are working on a 12V battery, which generates 13+ volts , is in fact working on a system where the 13+ volts is supplied by the DC-DC and thus the HV has to be live.”

This has not been debunked for over 2 weeks. The Leaf did do the start-up procedure and found a malfunction (P31E1) in the HV system,. It is inexplicable that the software engineers at NISSAN deemed it prudent to end the procedure and brick the car WITHOUT switching off the HV.

Am I going insane or is this a problem?