Sanity Check Request on HV Battery Trouble Code

Hello All!

Last night, one of our Prii pulled the Christmas Tree warning lights. It was driven to work and back earlier without issue. It kept running, and could be driven, but the yellow engine, the yellow exclamation point, the red exclamation point, and the warning on the MFD were lit. We took it home immediately and I used a handheld scanner on it and found only P0A80. My scanner is a generic one from Autozone, so I don't know if it can grab all the possible codes or not. A quick googling of the code produced "The difference in voltage between 2 of the blocks in the battery pack is too high" Prius PHEV TechInfo - EAA-PHEV and "Replace Hybrid Battery Pack" http://www.hybrids.ru/PriusNHW20/rm/rm1076e/m_05_0665.pdf

The car was behaving reasonably well, so I took it in to Toyota this morning. After examining the car, the service guy told me an HV relay was causing the trouble and was making the car think the battery was hosed. They are ordering the relay, and will put it in tomorrow morning under warranty. I the mean time, I wanted to check in with the collective Prius intelligence force if this is a reasonable explanation, or if I need to push for a more in depth diagnosis.

The car is a 2005 Prius with about 62,000 miles. It was bought used in 2007 with about 26,000 miles. It has smartkey, but not GPS or the multidisk changer. It is driven regularly, at least ten to twenty miles most days. We live in the Phoenix area, and the car is garaged at night. We replaced the 12V battery round about a year ago. The car is sluggish from a standing start, the ICE is racing much of the time, and the battery gauge graphic is very irregular. (goes from empty to full in a single, level stop, ect.)

If you want any other info, feel free to ask. I apologize for not getting the full name of the part they are getting. I didn't think to get a copy of the paperwork today as they will be doing the work tomorrow.

P.S. This is my mom's Prius, not the one in my profile. It is not the one I blew the big fuse on putting in an incorrect 12V with backwards polarity a while back, in case anyone is searching.

 

Alas, I didn't ask what codes they pulled. <face-palm> I would have thought a bad HV relay wouldn't let it start up at all.

The reader was a ~$60 model from Autozone, and less then a year old. It did successfully read several codes from my own Prius when the communication wire came loose from my CanView. It didn't help that the service guy said P0A80 was the inverter water pump, then some generic hybrid system.

My current expectation is once they do whatever they want to do tomorrow morning, the code will come back up and back I go. The symptoms sound alot like a failing HV battery to me, but I'd bet they don't want to start off replacing that. ($) I'll ask for a print out of the codes and a battery diagnostic screen when I go back tomorrow.

 

Well, day two still yielded no fixed car.

Yesterdays service guy apparently didn't talk with the tech and told me to completely wrong part. They ordered a battery ECU, not a battery relay. Well, that makes a great deal more sense. Once they got that installed, though, the lights all came back on and a pack of new codes came up. (I apologize! I didn't write them down again!) They went back to the computer, and found that they should have also replaced the hybrid vehicle ECU. That was, of course, not in stock, but will be in tomorrow. In the mean time, they sent me home with a loaner so I can go fetch the car at my leisure tomorrow.

I did confirm that they did a battery analysis which came up clear. Today's service guy and tech seemed to be rather more on the ball, and everything is still under warranty, so with any luck, the car should be in proper order tomorrow.

Just out of curiosity, for anyone who may have done it, about how long would you figure it would take one properly equipped person to remove and reinstall the battery ECU?

 

Best I could tell was they were working on it about 3.5 hours.

I'll be getting a full read out when they're all done. In the mean time, we've got a loaner, so they can putz around with whatever they want now. Both computers at once does seem a bit odd...

 

Well, waddya know...

They got the computer in and, sure enough, it blew again. They are now saying there is an internal short in the HV battery. Still warranty, and we've a loaner, but it will take until at least next Thursday. I will be requiring full documentation, as a dead battery is way outside of normal. I'll update when I get more info.

 

Hmm. That sounds rather interesting, considering what the service guy said initially. I haven't been in to the shop since Wednesday, when they claimed Thursday would see me a fixed car and the complete paperwork, so I didn't press for hardcopys then. I will see if they'll give me some paper today. (and all DTC's)

Would a damaged SMR cause a slow and intermittent degradation in acceleration? Mom had been complaining for a while about hesitation when starting. I had assumed it was the "lurch" from the traction control when the wheels slipped until I drove it. Instead, it felt like when the battery has drained out of its happy zone and was relying on the ICE to get going. By the time the warning light came on, it was pretty much all the time.

So, do I ask the tech to check on the relays before or after they put in the new battery? <Dr. Evil-pinky-finger-smile> On the other hand, we want to car back sooner rather than later...

I'll see if I can't actually talk directly with the tech. I have a feeling a lot of info is being lost between him and the service reps. I've been getting bounced between a few reps as we go. The last one actually told me the current failure was the "hybrid inverter computer battery." He meant the traction battery, but I sure haven't heard that name before. I'm not sure the computers were actually damaged per say. They seemed to be working with the concept "these codes involve these parts, so lets replace them and see what happens." Don't see a lot of actually troubleshooting and diagnosis happening here. I really need to get those codes...