2002 Prius HELP PLEASE

Hey there,

I've got a 2002 Prius and here's my problem. Last summer two warning lights came up, one was the main triangle with an "!" and the other on the screen was the car with a "!"

After driving a little bit, I noticed that the display started to dim, and then my screen started to flash like crazy and the car literally just "died" and stopped. We didn't really do anything to check the car once we bought it (used) except for an oil change and small clean up. Then we decided to check the spark plugs and most of them looked black so I bought new ones from Toyota and replaced them all. I also noticed the coolant level was pretty low so I bought Toyota's super coolant and filled it up. It seemed to be fine but every now and then the light kept coming up and sometimes it would still die when I started it up. I suspect it might be the use of A/C.

The car had been fine through the winter and up until now. Recently I checked the main battery and it turned out it was pretty weak, and I guess it DOES make sense since it's a 10 year old battery (not the hybrid battery of course, would NEVER touch that). So I replaced the battery and as soon as I started the car up yet again it stayed on for 20 seconds or so and went off, with the same lights coming up.

I guess it's still a win for me to buy a new battery since the old one was weak but can anyone help? Has this ever happened to anybody else?? I was reading this discussion and noticed people saying something about the "coolant inverter pump" and on hot summer days that could be to problem.

Any help is much appreciated!