Mysterious Hybrid System Light?

Hello Everyone!

Been awhile since I last posted...

Last time, I was talking to you guys on what to do with the Prius and if I should do an engine swap here: 2010 Prius Blown Engine - What are my options? | Page 2 | PriusChat

After almost a year, I finally decide to act (I know, I procrastinated quite a bit but wasn't in a rush...). About a week ago... my dad was able to move the Prius just a little bit while in EV mode so then the car would then be towed to the car repair shop (Cichy's Garage) in Williamsburg, MA that someone recommended in the above thread. The EV mode worked perfectly fine (no errors) though we the car was kind of left untouched for about a year on the drive way. Only thing that kind of kept the car on life support was some charger to keep the 12V car battery powered so it wouldn't go flat.

Car was towed to the repair shop but I was not present so I let the mechanic handle it from there so he can perform the engine swap. Today, after talking with the mechanic over email, he told me that the Prius had a hybrid service light come up when he moved the car to the garage before performing the engine swap though he did say that it did not impact the operation of the car? He did test drive the car and did not seem to mention any other problems other than this hybrid service light though. He also said that he would not be handling this kind of issue and would refer me to another place to have it fixed. I will be going down to the repair shop tomorrow morning to check out the car since I want to take a look but I am wondering if anyone here might be able to chime in or may have a guess as to why.

Seems like reviews for Cichy's Garage are good so I wouldn't believe he would pull a fast one on me but just curious why this happened...

I'm also assuming this is something you cannot simply check with a OBD II and need Toyota equipment to check specific Prius hybrid computer warnings? Hopefully I am wrong about this one.

 

That is very true. I did check the reviews of the place and people brought their prius here so not just me. Of course, doesn't mean they may be pros at fixing them but then again, there weren't many options around and they offered the most reasonable price. Another place nearby wanted to charge 2-3x as much just for the labor alone so that was definitely a no go. They also said they have plenty of experience with fixing Toyota Prius but that's what they claim.

Check Hybrid System with the yellow triangle on the left

I should probably bring it to a Toyota dealership to see if they could check the code for me.
The battery SoC when I started driving it after my dad brought it home from auto repair shop was around 75%. I noticed that when I cycle through the displays, it does not show the charging or power flow direction in the hybrid diagram and it appears that I cannot change driving modes (ECO or Power) during mid drive. I can select them in the beginning though but then the light indicator for the modes on the dash disappear soon after driving. I can still enter EV mode when I initially turn on the car though.

Not sure if I understood your statement "towing to the shop where you got the engine transplant would have been a better option" but I believe that was what we did. I apologize if my story above was a bit confusing. My dad used it to move the car just a bit in the drive way so he can get it in place so it can be towed by AAA to the auto repair shop. It would have been a good idea to take a picture or video recording of the state of the car as we delivered it to the auto repair shop but guess too late for that.

The battery SoC mini diagram does not seem to change as much as it used to. Before, the battery bars would change quickly if I use the car in EV mode when I do my pulse/glide technique but the bars still change though so I guess the hybrid battery seems to kind of work? Also, the reported MPG by the car seems to be in the 40s so I'm assuming the hybrid system works unless it's calculating the MPG in an inaccurate fashion.

Lastly, noticed that the rear windshield wiper cannot shutoff anymore (happened after it started raining). Looked on the forums and see that this problem isn't very isolated. I guess I'll just have to check in the morning to see if has dried enough or may have to pull the corresponding fuse to have it stay off.

 

Thanks for the possible causes. I'll have to take a look at that.

Also, would you guys know if there is some equipment out there that I can use to decipher the hybrid system warning light? I am hoping that there might be some reader tool that I can get my hands for that isn't too pricey online so I don't have to go to the dealer or to some hybrid repair specialist only to find out it's something minor.

 

Thanks! Will try that out and will report back with my results!

 

After receiving the cable and trying it out, it appears I have the P0AA6
Hybrid Battery Voltage System Isolation Fault.

Funny though.. that the day I got the cable, the car refused to get into Ready mode when I start the car so all of the lights on the dashboard are on like a christmas tree. I was able to clear the fault with Techstream and make the car drivable again. Fault came back soon after but at least the car is drivable for now...

Also, the Techstream software appears to be buggy (crashes when I do Data list or try to save the data during the health check up mode) but maybe it's because I'm running version 13 and running it on Windows 10 64 bit and it constantly nags that it requires Java 6 everytime I start it up. I will have to try running it on Windows XP virtual machine and maybe with an older version of the software.

Anyway, after doing a bit of research into this fault, it appears it could be related to a water problem. I'm with my dad right now and after further inspection of the rear area of the car, there was indeed some water by the hybrid battery. Hoping nothing too serious beyond that though.

I'll probably try to inspect the hybrid battery and check the cells as well since we're in there. Thanks for the help everyone!