Fixing bricked LEAF due to drainage of 12v battery

[Sanjuanderer]

I recently avoided towing my 2020 LEAF SV over 90 miles to the nearest dealership by using Leafspy Pro to un-brick it. After complete inadvertent draining of the 12v battery and subsequent AC trickle charging to reestablish 12v of charge the car was still bricked. The screen read something to the effect that there was "very low main battery charge", precluding shifting the car into gear. I could only shift into neutral. I repeatedly tried charging the main battery on 120v and 240v. It stopped charging after about 20 minutes each time. [I ultimately learned that the main battery was fully charged, hence stopping after 20 minutes of charging time]. I then used the app to identify DTCs (diagnostic trouble codes?) within the 'Service Menu' of Leafspy Pro. There were 3 pertinent error codes labeled basically as MOTOR CONTROLs (please see attached). I copied the report and then removed the error codes within the Leafspy app. This was followed by disconnecting the negative cable to the 12v battery for greater than 5 minutes. Reattaching the battery cable and pressing the start button revealed the routine screen messaging and the ability to put the car in gear. Although some of my preferences were lost, I was able to drive the car normally and have done so for more than 24 hours. Moral ... do not allow the 12v battery to die completely (if you can avoid it), as it likely will require a reboot of the computer system (probably at a Nissan dealership). I hope some poor stranded soul finds this helpful!

 

[cornbinder89]

Disconnecting the 12 volt clears the trouble codes, many can also be cleared with Leafspy. Either way that shouldn't require a trip to the dealer.
It resets to "factory" and yes your pre-sets will be lost, along with timer settings etc.
Just disconnecting the 12 volt and charging, then re connecting would likely do the same thing.

 

[Sanjuanderer]

Before disconnecting the battery, it's a good idea to take a screenshot of any trouble codes, as disconnecting the battery deletes them. If subsequent service is needed, the recorded trouble codes will help the service provider diagnose any problem(s) that need fixing.

 

[carconnection1]

Disconnecting the 12 volt clears the trouble codes, many can also be cleared with Leafspy. Either way that shouldn't require a trip to the dealer.
It resets to "factory" and yes your pre-sets will be lost, along with timer settings etc.
Just disconnecting the 12 volt and charging, then re connecting would likely do the same thing.

I recently acquired a 2015 Leaf with the 12v battery extremely low, and the traction battery showing zero charge. I disconnected the 12v battery and charged it up to max charge... Then an electronic battery tester showed it was a good battery. I reconnected the 12v battery, then slow-charged the traction battery overnight to 100% charge. Now the red 12v battery warning light is still illuminated, as well as the red/yellow triangles at the top left of display. I can't get the car to go into the ready position.
I tried 12 the 12v battery for minutes again, but still no green ready light. The 12v battery still tests at 12.4 volts with 100% charge.
Any help would be greatly appreciated

 

[cornbinder89]

1st make sure you didn't reconnect the battery backwards! There is a procedure on how (when) to disconnect the 12 volt battery to minimize the chance of setting a code, IIRC you turn the car on, then off then close the doors and wait 5 minutes for the car to go to "sleep" before disconnecting without opening any doors or turning anything on. So have the hood open before you start.
Other than that, we need to see DTC's to go further.
A car purchased with a very low 12 volt points to a pre -existing problem.

 

[Stanton]

I recently acquired a 2015 Leaf with the 12v battery extremely low, and the traction battery showing zero charge

START A NEW THREAD. Your issue likely has nothing to do with the thread you posted in (and this thread was more of a "good to know"--not a problem to be solved).
The first question will be: who/where did you acquire your Leaf from and why did you purchase an EV that was (apparently) "dead".
I'm not going to add any more to this thread.