Paul, New 2003 owner runs good but warning symbols come on frequently

I bought an 03 with 58K miles on it. shortly after I bought it the check main battery light came on, after the local Toyota dealer told me I needed a new main battery ( 5 to 6 K $ installed! ) I started looking for an independent mechanic with some Hybrid experience. I was lucky to find a good shop locally (I live in Hilo, Hawaii) with at least as good a diagnostic machine as the dealer. I had a P3000 code, a high voltage leak. It turned out to be corroded buss bars and cables, with 2 leaking cells, $1,450.00 latter the onboard computer said the problem was fixed and my display read normally for about 1,500 miles before I started getting that code and the check main battery light again. I took it back to the shop tat did the work and they ran the diagnostic's on it again, checking the main power cables that led from the main battery under the car to the Toyota Hybrid system, inverter? under the hood they checked all of the high voltage connections, they all checked out fine. The shop then took several days to do an online search for possible causes. This led to the CV trans axle with its electric motors and generators as the possible culprit. The car is running and driving fine, so I did the 60,000 mile transmission oil change, suggested by my mechanic ( apparently the fluid becomes conductive with age) the check battery light will go off if I remove the secondary battery terminal for a minute or so and stayed off for 2 tanks of gas after the fluid change but it did come back on. I can reset the computer easily enough and it will stay off for 3 to 400 miles but I'm looking for any other ideas to get the damn light to stay off. I'm going to change the trans fluid again and then I'm about out of ideas. Has anyone ever changed the drive motor or generator?, can this be done in the car? or at all? It may be that if this is the problem it may end up making sense to just put in a new CV transaxle, I can get one for around $3,500.00 any thoughts or insights?

Aloha, Paul B

 

Thanks for the feedback. This is new technology to me so I am trying to get up to speed' Where might I obtain a Prius aware scanner? I've seen references to a Mini VCI, is that a different type of device? I find it odd that, while the dealers will charge you for running a diagnostic on your car they won't tell you what, specifically, is wrong, just bring it in with a bag of money and they'll fix it!

 

How do you know if the transaxle is overheating? I removed the inverter coolant fill cap and the coolant was burbling away in there. so the inverter coolant pump is good. Is that all part of the main engine cooling system or a separate system? what type of coolant is used, standard antifreeze? I assume the transaxle is cooled by the engine's radiator, Auwe! so much technology!