I drove for 20 minutes this morning. It was around 65 degrees and I didn't use heat nor airconditioner. After the engine was warm (a little below half on the idiot dial) I had a few red lights and sat for 30 seconds, or more. The engine ran for about 8 seconds and shut down.
Later on, I drove another minute or two. The car was freely going in and out of the blue.
The non-NAV diagram showed almost full battery. I coasted down hill for about 3/4 mile and the car was in the blue. As I slowly coasted to a parking spot (when you're first person in, you can do that), the diagram showed wheel>engine.
The engine turned on (I was coasting ~10 miles per hour). I pulled into a spot and put the car in park.
I sat in park and waited for the engine to turn off. It idled (in park) for about 2 minutes.
Now, here is the question...why, with a full battery, warm engine and after a few lengthy red light stops would the engine idle for that long?

 

I also have experienced this weird hybrid type problem. Mine happens usually in the large Walmart parking lot here in town. The TCH seems to get hung up with the engine running even though it's mostly level and some areas where I can coast. All this with a near full battery.

Now that I think of it, the parking lot problem is after we get in the car to drive home. This is after being in the store for near a hour. Some nights it's 85 degrees at night when we walk back to the car. Even though the engine is still warm, could be the temp level is not yet up to a full operating temperature.

haroldo, yours was already at operating temperature with the stopping at a few red lights then entering the parking lot. It only takes about 3 to 4 miles for the car to get to full heat.

I have seen this similar problem on the way home where the car should go to the EV mode but don't. Thats even with the engine at normal operating temperature.

I have noticed that toyota likes to run the cold or cool engine till it's completely heated. It seems to hold heat better once at full heat once it starts it's shuting down.

I sometimes wish I had a manual switch to switch it to EV Mode only when we see the battery over 60% full.

 

I've had my TCH do something similar in a couple of different situations.

1) In city driving if I'm in EV mode and the ICE kicks in I will just lift off the gas and let it go back in EV mode. If I do this 2 or 3 times within a short amount of time the TCH will refuse to go into EV mode until the car gets to a speed of 60kmh/40mph. Something in the software resets and I can get into EV mode again.

2) Driving to a cabin over a very rough path I was trying to let the car get up an incline in EV mode. It was barely crawling as we reached the top and then the ICE kicked in. I could not go faster than 30kmh/20mph on this 'road' so hitting 60Kmh was out of the question. But even turning off the car and restarting would not get the car to go back into EV mode. I am guessing that letting the car crawl in EV mode (high load on the incline) may have got something hot and the ICE was running to let it cool but that is just a guess on my part.

 

I've had the same thing happen to me. This past weekend I went to the IL Renewable Energy Fair and met up with members of the Chicago Prius Group. I was describing this problem with another Prius owner and he (an engine designer/builder) said that at times like that the engine is actually using little gas and is cleaning out the cylinders prior to shutting down. That's not technical but that's the basic explanation that he gave me. He said it is normal and is just something that the engine needs to do at times even though conditions are ideal for it shutting off.

 

What accessories did you have on - AC, lights, etc?

 

Lights, radio (AM...WFAN)...that's all

 

I'll add my 2 cents as I've seen that as well. I've had this happen and under the same circumstances as others have mentioned, slow driving between 10 and 15mph thru a parking lot that triggered an engine start, and then coming to a stop the engine just won't shut off. If there would have been room to get the car up to 30 to 40mph then coasting/braking surely the engine would have shut down no problem.