Can anyone help with a dtc C1259 on 01 model?

I recently bought an 01 model that I knew had bad batteries. It has 246,000 miles. The codes that were in it when I looked at it said that the hybrid battery was bad. It had a bad aux. battery as well. There were a couple of C codes that I couldn't get much info on. Thanks to Prius Chat and those that have contributed, I already had a battery pack for it reconditioned with gen 2 modules.
NOTE: When I pulled the traction battery out, it had been so hot that it burnt the wiring harnes up that plugs into the ECU and melted a lot of the plastic that covers the terminals and wiring harness. It even burnt the sheet metal around the ECU end and burnt a hole in the carpet that covers the battery pack. This car could have burnt to the ground. I'll try to post the pics here.
I installed the HV battery and new 12V Saturday evening. The car started up, ran a few seconds, and then the warning lights lit up like a Christmas tree and the engine shut off. So I hooked the laptop up to it this morning and retrieved the codes.
They were:
P3191, 3101, 3140
C1521,1522

I bought a subscription to Alldata DIY to see what the codes meant. I then went straight to the safety disconnect plug, removed it, put it back in, and made sure it was latched. I cleared the codes and ran another health check. This time all I got was a C1259 and just the "brake" light lit in red. Alldata suggests it could be 1.) a votage of 10.5V or more for 1.5 seconds or 2.) a regenerative malfunction occurring on HV ECU side. I don't know enough about this car to know what "normal" is for everything. So I drove the car and all the drive train seemed to be working properly, including the braking position (regenerative braking). The front left brake sounded like I need to inspect for brake wear or something, it made just a little noise as the wheel turned. Could worn brakes cause this code? I haven't pulled the rotor off yet. I tried to clear this code out a couple of times and it just stays there and the brake light stays on. So I tested the brake light to make sure I could turn it on and off via techstream. It worked. There were several other tests available in techstream but I just didn't know anything about what they were. I've never messed with any other parts of a prius other than changing a rear wheeI hub assembly on my 01 (thanks again PC!). I couldn't get any more info from Alldata on how to proceed with the diagnostics so I am at a brick wall.
HOPING someone can help me out!

 

I didn't notice any codes in the individual sections. I have the mini vci with techstream but I don't know everything I can do with it. I don't play around on it too much. Someone sh

I'll check again but I don't remember seeing any codes in the individual sections. It may be possible that something is broken or burned. I'm not sure how to trace it down. How much does the techinfo.toyota cost?

 

Not sure if the previous owner kept driving after the warning lights came on. He said the car just quit one day. After I first cleared the codes this morning it started and ran fine. I don't know what maintenance it's had done. But it drove OK. Just couldn't get rid of that code.

 

I can't remember how to put TS into "test mode". Someone showed me how last year but I haven't needed it til now. He said it increased the sensitivity so it would pinpoint the problem when you drive it.

 

All I can say is God is good! I hooked the laptop up this morning, cleared the code again, and ran another health check. It was gone! I drove it about 5 miles and still no code. My guess is that when I first put the safety lock in I didn't get a good connection and it just didn't like it. Whatever it was, I hope it's gone for good.

 

The car I started this thread about is the 2nd 01 model I've bought, since my wife liked my car better than her 06 model (why, I'll never know!). I bought the 1st one with 122,000 miles on it and bad batteries since I had already rebuilt my wife's 06 battery pack. The last module, #38, had a hole burned in it and the ring terminal on the sensing wire that should have been on there was completely gone. It also melted the casing of mod # 37, almost completely through. I pitched those 2 immediately and 2 more after I started the reconditioning since they didn't want to cooperate. Since I couldn't get the capacities close to 6000 mAh I bought a used pack out of a front-end wrecked car. That pack only had about 4500 miles on it as verified by the invoice from the dealer. The dealer had to put new batteries and tires on it to sell it and the guy that bought it had it less than 6 months when it was wrecked. So I bought the batteries (HV and aux), tires, and a marker lamp lens on the front bumper since that was exactly what my car needed. The 12V battery only had 1.36V when I brought it home. I never expected it to come back to life but I figured what the heck, it can't hurt to try it. I put it on the charger and for 4 or 5 hours it didn't do anything. I was about to pull the plug on it when I got sidetracked for about 3 more hours. When I came back it was charging! I left it charging overnight and the amp guage was back to 0 the next morning. It was alive!! I definitely believe those are good batteries (GS YUASA).
Since I still have an original 1st gen pack in my car now, I have decided to check my bus bar/wiring connections at 175,000 miles. I expect I will remove the bus bars and clean all connection as a preventive maintenance. Whenever this battery fails, though I hope it's a long time from now, I will replace with a retrofitted pack of gen 2 mods like I did on the car that I bought for my wife. So far I've put 23,000 miles on mine with no battery problems. I just had to replace a rear wheel hub and I didn't know if it was coming out or not. It got pretty ugly, but I was able to persuade it with 2 shop hammers.