ICE starts then shutters to a stop

I've been trying to figure the problems with my wife's Prius. Its an '02 with 59k miles and has had all regular dealer service performed. Recently she had the engine... (best described by quoting an older post from Green in CA):
Car starts right way
Within 5 seconds, he gets the red triangle of death
It says "Problem" and then the engine shudders to a stop

I finially experienced this problem today for myself. Only for me it wasn't cleared by just shutting off the car and restarting. I must have tried that 4 or 5 times and it shuddered and died each time right after "Ready" appeared. The vehicle was in Park the entire time. Since I was getting parts to replace the 12v battery (yes, the original GC one) I had the felt door off. I pulled the large wire plugged into the connector on the positive side and plugged it back in. The car started and ran fine, no check engine light either.

The car has been to the dealer twice to be checked (total cost about $150.) Each time they can't find any problem though they can find error code P3191 (failed to start.) I'm replacing the 12v battery because its about time and its resting voltage is only 12.50 with the car off (after a drive to get it charged, measured on the battery.) I don't think the dealer knows how to do much more than check codes :-(

Thanks for your help,
Paul G.

 

<div class='quotetop'>QUOTE(Paul G. @ Oct 7 2007, 02:45 PM) [snapback]522513[/snapback]</div>

I wanted to add that replacing the original battery with a U1-R AGM (like a Miata battery) seems to have cured the P3191 will not start problem. Hopefully I can get back to working on real electric vehicles (and working overtime, and working on the house...) Days are far to short!