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Toyota Prius Software Problems
The Prius uses computers to a degree not seen before in a production vehicle. Pardon the cross post, but to start out the discussion, I wish to repeat part of post 134 from the "Problems and Solutions":
md_sailor, "Toyota Prius Owners: Problems & Solutions" #134, 22 Feb 2005 11:15 am
I was driving home last week in my 04 Prius, watching the mpg reading creep up to 48.0, when I stopped at a stop sign. Immediately after starting up, my dashboard lit up with multiple failure warnings, including "VSC", the red triangle around an exclamation point, a yellow circle with exclamation point, etc. The car continued forward, but just on battery power. Since I was only 2 miles from home I decided to continue, and made it into my driveway by coasting the last 1/2 mile.
The car then stopped and would not move forward. I turned it off and read some of the manual. After a few minutes, I pressed the "ON" button and this time the gas engine started, although the mass of warning lights stayed on. I got the car into the garage, where I left it running to charge the battery (garage door open of course). While I called Toyota, the car stopped.
After having it towed on a flatbed to Toyota the next day, the car was fixed by reprogramming the ECM (engine control module). So far there is no explanation from Toyota for the failure, I'm trying to work my way up to someone who actually knows something about the computers. My confidence in this car, and Toyota, was badly shaken by this incident.
The problem here is that there was a software error in the Prius. What most people do not realize is that it probably wasn't fixed by the dealer.
What happened: The Prius in question hit a point in the software code that caused the whole program to crash.
How it was overcome: The Toyota dealer installed the same program back into the car. There is no way that Toyota made a program modification and then put it back into the car.
This means that the Prius will fail again if those exact circumstance occur again. It also means that every Prius with that same software version may fail in the same fashion
There are only a couple of possibilities here:
1. Toyota already had a fix for the problem, and hadn't installed it in all cars. Possible, but unlikely.
2. Toyota simply put the old code back into the vehicle and hoped for the best. Probable.
Hopefully, Toyota at least had the smarts to download the entire memory contents (or enough code to troubleshoot the problem). A simple error code is not usually enough to determine why the code failed, only where it failed.
I find this troubling because the basic HSD technology and programming is now about 7 years old. It should not be hitting failure points like this.