Not sure where to put this but .... My 2018 Prime started displaying the "Hybrid System Malfunction- visit dealer" message a bit about 2 weeks ago. Given it still had the original 12V and a weak 12V can cause that error, I replaced it about 10 days ago. All good for the drive home. Next drive, message came back. I made an appointment at the dealer for this morning. Today they looked at it and said it had severe rodent damage to cell blocks 3-4 & 5 and the battery and its computer need to be replaced. Comprehensive insurance will cover it less the deductible. So I asked the service lady how long it would take to get a battery. She checked with the parts dept and the answer was (sit down) There are none in the country (USA) and Toyota isn't making them any more. Weird since the same battery is used all the way through the '22 model year. Now we wait for the dealer and Toyota to find some resolution to this "issue". No idea what that might be, she said it usually takes 24-48 hours for Toyota to get back to them. I have no idea how a rodent can get into the battery case, seems like that would be sealed up really well. This is especially painful given 1) I like my car and it has only 57K miles on it and 2) we have been waiting 5 months for a replacement battery for the Leaf. There are 2 people who had been waiting (and still are) 3 months when ours started to fail in Dec (cold temp while under load, runs fine in the warmer weather) and 6 more have been added to the "you'll rot in hell before Nissan comes up with a battery" list since we were approved back in January. I had (inaccurately) assumed Toyota would be in better shape than Nissan.
Sorry to hear that. Mice can get in through the battery cooling intake and exhaust vents. An alternative path would be to install a battery pack from a wrecked gen4 or find a facility that's willing to do a repair. Dealerships mainly do assembly swaps, they don't do real repairs. Some place that does traction pack rebuilds should be able to fix it. I doubt the traction pack ECU was actually damaged. I used to work on large battery UPS systems and would occasional find a rat that bridged the wrong two power bars. That never resulted in any damage to the control or charging circuits. They sometimes popped fuses, which is what they are suppose to prevent. Hope this helps - Good Luck...
