2005 with Rebuilt Pack, now Codes C1241 and C1310

I'm hoping one or more of the experts can help with my mom's Prius problems.

At 98K (on the Prius, she's 89), she fell, broke her wrist, and didn't drive for two months. After the car was put back in use, the hybrid battery was dying. I kept the Prius limping along for the hot two months of summer, and then it finally wouldn't back up, but I just managed to get it going and got it home.

I found a set of 2010 modules, 89K miles on them, from Bernie at eLearnAid. Bernie is a spectacular guy, completely honest, and very helpful. The modules arrived, perfect condition with meticulous packing. I pulled the pack, replaced the modules, put the pack back together and installed it.

I promptly had all the problems with the safety plug, even though I was careful. I took it out and reinstalled it several times, and it finally seemed to be fine. I was celebrating like it was 2010!!!

Until I drove it for about 25 miles. The red triangle came on, the little (!) light and the VSC, so I got it home. Turned it off, but trying to restart it wouldn't go into READY mode. Disconnected the 12V, and drove it again. This time it didn't make it out of the driveway. I repeated the procedure, and got it to Advanced Auto, where they pulled the codes. It indicated ABS. I once again cleared the codes, and tested to see if it happened when i was stepping on the brake pedal. I found out it could happen whether or not the brake pedal was being pushed.

I got the 12V tested, and it checked fine. I had heard one somewhat unusual story where they had similar codes, emptied the tank, and it was fine. I've got half a tank left, and would be patient enough to drive it to empty and refill it, but for the NEW problem.

Today, the dashboard went completely dark. I'm not sure if this is somehow related or not, or if a fuse has blown during the 12V reconnection, but this still seems like a secondary problem.

So, is it also somewhat just a coincidence that the C1241 and C1310 showed up after reinstalling the battery pack? Or is it more the time factor of the Prius not being driven, bringing on all the problems?

I'd hate to start replacing parts blindly. I've looked into the Torque app, but don't know if that should be the next step to help with the diagnosis.

 

I disconnected the 12V overnight, and it did not help with the dark dashboard. However, I did the FOB procedure (Foot on Brake, Lock, Lights On, Lock again, Start) and it now works!!! I'm not sure for how long, but it works.

So, that turns the attention once again to the C1241 and C1310.

I've tried to do a bit more experimentation, as I'm thinking about the person who said with new gas the problem went away and has never returned. So I've tried to drive it daily, going a bit easy on the braking. I've gone to 29 miles without the codes, I've gone on several short trips of 6 miles or so, no codes and restarts fine, only to get the code at 26 miles. Finally, it seemed driving in B mode it wouldn't come on, it was only when I forgot and went into D, although that too could be just coincidental.

So I'm wondering, is the C1241 and C1310 codes enough to cause the Prius to go dead on the road, or into some reduced power mode? Can I burn through the rest of this gas and refill it before I'm absolutely positive I've got to go to the next steps?

I worry a bit because the other day I stopped to help a dead Prius on the road. She said she was just able to coast into the turning lane, and then it wouldn't restart. I tried with the FOB inserted, and it seemed a bit like the dark dash, as it was just flashing squares where the B,D,N,R would be. I would have tried to disconnect her 12V if it had been pulled off the road, but it was impossible sitting there in the turning lane. If you can believe it, the car not moving, the hazard lights flashing, and people would still pull up behind her, wait and wait, then beep their horn. I was wishing I could have helped her, but even pushing the car to the shoulder wasn't an option across all the lanes of traffic.

 

I have done more testing and research, and I'm hoping one (or more) of the experts might give their opinion.

First, I don't really understand why one code C1310 can be related to so many different problem areas. It seems it can range from a bad 12V to bad gas to a loose nut on one of the hybrid battery cells to the ABS ECU to possibly even a failing transaxle that needs replacement.

So, what is confusing is that the code, along with the C1241, doesn't appear with any consistency. I've driven 29 miles, 26 miles, and now just 2 miles with the code coming on. I've driven in B mode, and the code will come on. It has come on when I've been pressing the brake, and when I'm just driving. It has come on when the car is cold, and after it has been warmed up.

I've somewhat been trying to use up the remaining gas in the tank and refill it, not that it has a high probability of success, just that it seems a bit easy to do, and in the intervening time I can do more research.

I've had the 12V tested, and it has tested fine. It is an Optima, just over 14 months old. It was tested while in the car, although the technician who tested it stated he'd have rather had the battery out of the car when he checked it.

I have rebuilt the pack with replacement 2010 cells, which tested fine. I did not have an easy time putting it back together, as it takes just that bit more strength than I have to push the cells together to get the end plate on. Somehow I finally did manage it, but not until I redid all the cells several times trying to keep them as close together as possible when assembling it.

Now, according to this thread: 2007 Prius with C1259 and C1310 - any ideas? | PriusChat , it could be a loose nut for a cell sense wire. I was extremely careful. I even purchased an inch-lb torque adapter to be sure. But then I start to wonder. But I wonder more and don't understand why there wouldn't be a code indicating a sense wire wasn't reading properly.