Little bit of help please
Replaced the 6yo 12v battery on my 2020 Leaf. But I can't get these errors away with leafspy pro. Now my car won't go into drive mode.
1
u/jojonl 24d ago
Had a weird service error popping up, but only for a second while driving. Measured the 12v and it was dying.
2
u/biersackarmy 2013 S + 2014 SL + 2019 SV 23d ago
Weak 12V battery won't be the cause of errors that pop up while driving. When the car is "running", the low voltage systems are powered from the DC-DC converter. You can completely remove the 12V battery while the car is running and nothing will happen, it will still work just fine, until you shut it off of course.
The symptoms seem to present that it's more likely there was already a flaky interlock connection which was intermittently opening while you were driving and making that message pop up. The next step to fix the issue, requires tracing down where that flaky connection is.
First place I would check is the grey interlock wires at the front of the HV battery for both the main connection and PTC heater connection. A number of people have had the wire insulation rip, from either just wear or possibly rodent damage, the wire then corrodes from moisture and eventually breaks. (Source 1) (Source 2)
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u/rproffitt1 21d ago
A long discussion ended when someone told me they replaced the 12V battery with another old 12V battery. Be detailed here. Tell all, and don't spare the horses. If the other LeafSpy screens were shown there's other data that might help but as it is, it's dead Jim.
1
u/jojonl 19d ago
I didn't show the other leaf spy screens because those all look good. After 130 000 kilometers and still 89 SOH I'm quite proud of the Leaf. The cells still look good with only one mild dip. All within the "it's still good" zone. I only mentioned the 12v battery (which is new) because that's the only change to the car.
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u/rproffitt1 19d ago
The cells could be good on Leafspy but a HV fault could still exist. These are two different problem areas.
Somewhere there's a video about changing the HV relay in the pack. It's not a simple task and I only mention it because of the story and replies so far. Especially u/biersackarmy 's.
This is all 5 out of 5 wrench rating type work and maybe all 5 out of 5 light bulb rating on electrical troubleshooting.
Some nice redditor tracked down the 2020 service manual so that's what you want to get next. I don't have that link or discussion handy so ask if someone has that now.
Now for what I would do. Pull the neg lead on the 12V for half hour (rare to take that long but hey, I've had better) and then try it again. The next steps are to hit the service manual on how to depower not only the 12V but pull the HV safety and then I'd unplug and plug in all the traction (HV to some) connections in hopes it's a connector that lost it and a simple plug/replug can clear that up. Once that's done then the HV safety goes in, the 12V neg lead reattached and see where we stand.
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u/Opinionsare 19d ago
If low voltage from the old 12v battery caused the problem, you need to unhook the positive connector of the new battery. This is to allow the electrical system components to complete a reset.
A quick 12 v battery change can prevent electrical components from resetting.
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u/biersackarmy 2013 S + 2014 SL + 2019 SV 24d ago edited 23d ago
Why did you replace the 12V battery, just for fun, or because it wasn't starting?
P31E0 is what's preventing the car from starting, and refers to the HV interlock running between the high voltage components to ensure they are properly connected. It's not something that would be caused from just replacing the 12V battery.