Check Hybrid Battery

Hello everyone! It's been a while since I last checked in. I apologize for my absence. After encountering some recurring issues last year following the head gasket repair on my Prius, I decided to retire the car and bought another one to serve as my daily driver. (Prev thread: Head Gasket Replacement on Gen 3 prius | PriusChat)

I had been postponing the sale of the Prius to Carvana with the intent of transforming it into a project car. The plan was to address all its issues, replace suspension components, give it a fresh coat of paint, and more. Unfortunately, due to financial constraints, this project has been put on hold. As a result, the car has been parked in a lot since June this year, patiently waiting for its makeover.

In June, I began to notice that my car needed to be jump-started every time I attempted to use it. After diagnosing the issue, I realized that I needed to replace the 12V battery. This replacement was done today. However, when I tried to start the car after the battery replacement, a message popped up on the screen saying, "check hybrid system."

I turned the car off and decided to recheck the new battery installation. During this inspection, I noticed that I had forgotten to connect a cable that should have been attached to a metal bar. After connecting this cable, I attempted to start the car once again, only to find that the "check hybrid system" error persisted.
In an attempt to resolve this issue, I also tried resetting the errors by unplugging the white cable located near the fuses. Additionally, I experimented with putting the car in maintenance mode to initiate the internal combustion engine (ICE). Unfortunately, none of these actions seemed to resolve the problem.

At this point, I'm inclined to believe that the issue might be related to the hybrid battery itself. The symptoms I'm experiencing are similar to those described by other hybrid vehicle owners. I encountered a similar error and check engine light approximately a year ago, a few weeks after I had replaced the head gasket. Back then, I managed to temporarily resolve the issue by unplugging the white wire. However, it resurfaced after about 200-300 miles, prompting me to repeat the process. This time, it only provided a brief respite of 20-30 miles, leading me to give up on this car.

Now, I am determined to fix the car once and for all. However, following the replacement of the 12V battery today, the car refused to start at all, even after removing the white cable for a few minutes. I was able to start the car and drive a couple of miles back in June before I parked it where it currently is. Now, after putting in a 12V battery I’m getting this persistent message and it cannot be reset

It appears that I may need to address both the issue with the hybrid battery and the previously experienced chain tensioner/chain/solenoid error. Here's pretty much where I ended my tinkering with prius Head Gasket Replacement on Gen 3 prius | Page 5 | PriusChat). My plan is to first tackle the hybrid battery problem and subsequently relocate the car to a friend's garage to address the chain tensioner issue.

I've identified a YouTube video for replacing the hybrid battery that I intend to use as a guide (Replace hybrid battery). My preference is to replace only the faulty cells rather than purchasing an entire set. Can you recommend where I can acquire these cells at a reasonable cost? I also plan to obtain or borrow an OBD code reader from AutoZone to identify the number of faulty cells. Does this approach seem reasonable to you?
As always, I am immensely grateful in advance for any assistance and guidance provided. Thank you!

PS: Formatted with ChatGPT, please ignore the overt language :|

 

No, the head gasket replacement went fine. The issues started cascading after the replacement and when I posted the error codes and follow up pics on the previous thread, a user recommended replacing the chain and tensioner. So once I figure out the Hybrid Battery and am able to drive, will resume working on the other issues that might crop up.

I'm still in 2 minds if I want to sell. I am simply trying to get it into a running condition while I decide what I'd like to do with it.

 

Interesting read! Will look more into the charger, hopefully I can loan it from some mechanics near me who specialize in hybrid cars? Or hire their services?

As for gen4 replacement, I'd like to see if I can still get it running. Thanks for the contact, will seek assistance if it's too big a job.