I have a 10 month (15,000 mile) Prius and the " check hybrid system" warning light came on while driving on the interstate. 17 miles later the car quit running. I had it towed to the local dealer and after taking a looking at it I was told the error code pointed to the water pump (which they plan to replace). Does that make since? Has this been a problem for the Prius IV? Thanks.
The flawed water pump was replaced and shipped somewhere for examination. There was no determination at the dealer of why the pump failed (no coolant leakage). Lessons learned - The warning light does not tell you to stop the vehicle immediately. You don't find that out until you read the owner's manual sometime later.
There have been threads where people were berated for not pulling over immediately once the warning light came on. Many live in rural areas where there is no towing or cell coverage and this simply isn't an option. My '82 Corolla made it over the Grapevine and into LA with a bad distributor cable. I was in the slow lane with the pedal to the floor but I made it. Some trips I took back then, out to the Mojave in 115 degree weather on roads that averaged one car every 3 days, could have ended fatally if I'd been driving anything that stopped running without warning and couldn't be re-started to go at least go 50 miles.
There are two water pumps on the Prius, one for the engine and one for the inverters. On the Gen 3 both are electric. I suspect your failure was the inverter water pump and may have been electrical in nature, thus no leakage. It would also let you keep going until the inverters overheated. Somewhere on this site is at least one (maybe more) other report of an inverter water pump failure. There have also been several engine (ICE) water pump failures and there is a TSB on that one.
