Stumped

New to Prius chat. Been reading for a while, but my Prius has been so reliable, that I have not stopped by that often.

I have a 2005 Prius. It has 120K miles on it. It has been the picture of reliability until 5 days ago. We went on a trip and left the Prius in the garage for 5 days. It was hot while we were away, but nothing Phoenix-like – just 100 degrees each day – here in Oregon.

I came back and was ready to do some errands and started the Prius. Triangle of death, plus a few other lights came on. Did the check the 12 v check and it was low – 11.6-11.9 volts. Turn the car on and it popped right up to 14.2 volts. Ok – I thought I had been on borrowed time on the 12V (it drained a couple of times and I needed to charge it with my Jackery) – so I replaced it. I also purchased OBD plugin monitor and downloaded Mr Prius and paid the $13.99.

Mr Prius came back with just one error code P03000 or something similar, which I think is just that the triangle and check engine light are on.

I was able to clear the codes and start the car, but the symptoms started to change and things were spiraling downhill a bit.

Mr Prius showed pack voltage of 230.28 volts, #1 was highest at 16.71, #2 was lowest at 15.19. All others were 16.49 to 16.65 volts. All the internal resistances were 19 m-ohms. 12 volt battery showed at 14.2 with the car running. (With the car off the new battery went from 12.1 when installed to 12.4 after driving around the block.)

Here are the symptoms that concern me.

1. I have never heard the battery fan running before, but now it is constantly on – presumably on high. Regarding that, Mr Prius showed 131-142 Deg F on the 3 areas in the monitor. Earlier, this had been 85, which was close to ambient temp. (The jump in temp has me worried, along the fan running, when I have never heard it before.) I just checked it again and they were higher 140-160F.

2. There seems to be more clicking at the start than I remember – like connections closing or trying to close. I might be overthinking this.

3. When looking at the hybrid level in the car display, the battery level would jump around, going down as low as 1 bar and then slowly work its way back to all bars except one. I never noticed it jump down, just that it was down. This is new.


I can run whatever tests folks think of value and take screen shots.

The car seems to run ok, but I did not like it that more things seem to be going off.

I don't want to lose faith in the car.

Ok - last - completely different item. Every time I get the car checked, the mechanic comes back with that the brakes are at 45-55%. I have never had them worked on. Same with my old Highlander Hybrid. If I brake slowly, do the brakes shoes last forever?

 

Thanks for the info. I have reviewed your whack-a-mole and that gives me some pause regarding the replacing just the lousy module. I can buy modules for ~$35 each, or a remanufactured battery for $1500 (2 year warranty and including shipping) or ... I have reviewed videos on replacing the module and replacing the battery. Both are well within my DIY abilities. I am now asking for a suggestion. We have been running this car 400 miles per week during the summer (20 miles per week during the winter), specifically for its great gas mileage (46-52 mostly depending on the wind direction.)

I am now looking for suggestions. If I can get 2 years out of whack-a-mole, I would be happy - if I (or my wife) will not get stuck on a highway somewhere in the middle of the night.

Still a bit concerned about the battery temperature readings. But I went out there today and just monitored the battery without starting the car and Dr Prius was saying 112.12, 119.59 and 108.40 and the garage temp was 75, so the thermistors might be out of calibration. I have cleared the P3000 error and the car runs normally, but 3 miles in, the triangle warning light would come on, along with the P3000 error code - no others. And the battery fans would come on.

We wanted this car to be stick around for 5 more years as a bridge until electric and self driving cars are further refined.

 

Thanks to those that wrote. Here is an update. With the 99% certainty (see above comments) of a bad cell in one of the modules, I called Hybrid2Go and they quoted $1499 for a rebuilt battery with a 3 year warranty. They said it would be 2.5 weeks to get a person out there. Ok - so rather than wait (and potentially have this later be pushed back further) so I bought 3 modules from eBay and thought I would give it a go with the whack-a-mole method. As I am waiting for the package from eBay (2 day delivery), Hybrid2Go called back and said they could be over the next day. Ok - I wasted 80 bucks on the 3 modules, but it would be done.

The Hybrid2Go person showed up and got to work. Great guy with lots of insights. Best part to me was that he showed up in a Gen 2 Prius - like mine and he loves Priuses and rebuilds them. Some comments of his: I had already disconnected both the 12 volt battery and the hybrid battery. The tech was disappointed in that he could not run his diagnostic program as I had eliminated potential codes. I said that I had Dr Prius - which he gave good scores for, but only on the battery - and I only had a Code P3000. So if you are thinking about having someone fix your car, consider leaving it alone so they can check the codes.

Second comment, he noted corrosion on the hybrid battery fan connector. He said this is from a little leak in the body frame and I should watch this. He suggested sealing the roof with some sealant. The corrosion was minimal - green on the plastic connector housing - but I thought it worth noting here.

FYI - while I was waiting, I disconnected the Hybrid battery fan and cleaned it. I took it completely out of the car and had it on the work bench and with 100 Q-tips, got all of the blades clean. It was not bad at all - kind of like a room fan that needs cleaning, but not much more. I was hesitant to open it up as there was a foam gasket at one end that would have ripped (glued in place). The Tech told me I did not need to worry about that - just slit the gasket - it was only to help with airflow and not really important - and take the whole thing apart. That would have been good to know. I took 60 minutes cleaning each fin through the discharge chute, when 10 minutes with an open assembly would have been nice.

After a small hiccup, the tech had the new battery in and everything fired up just fine. The battery temperatures were reading ambient. One small concern is that the new battery had higher internal resistances ranging from 23 to 26 milliohms versus the old battery at 19-20 milliohms. New battery voltages ranged from 15.56 to 15.78 volts. (Dr Prius's autoranging scale display made this look bad. I had to look carefully.)

I did have a problem with Dr Prius and Lifetime checking. The app would simply close in the middle of the 800 second test of battery life. Did this 3 times.

We took the car for a short test drive and now for a longer (200 mile) drive. Need to develop that sense of reliability back. It will be interesting to see if the gas mileage will be similar - I expect it will be.

Thanks again to those that commented. Hopefully, I can update this in 1 year.