Hybrid controlling unit overheat

Dear all:

My friend bought a Prius III last year. Today he drove his family, 4 adults and 2 children in total, going up a mountain. The journey was about 39 kilometers, and he drove in “power” mode in the last 10 kilometers. However, just before they arrived at their destination in 500 meters, their Prius refused to move, and the dashboard showed that “the hybrid system is overheated”. 3 minutes later, the warning disappeared and they moved toward their goal once again. While they almost got arrived at the parking lot, the problem occurred again.

Fortunately, they eventually arrived at the destination and they did not encounter the same trouble during their way home.

My friend told me that the cooling water of hybrid controlling unit is full, and the HSD battery blowhole in the backseat was not obstructed by passengers or staffs. He posted this unpleasant experience in a Prius Club in Taiwan but nobody could tell how this could happen. Is anyone here would suggest that what parts should we look over, in what situation this problem might appear, and how to keep off such problem?

 

1. One of the two children is 5 years old, and the other is just two. Prius is capable of carrying 5 adults, so I think they did not exceed the weight limit.

2. My friend said that no sooner had the warning appeared then he immedeately turned his head and inspected whether or not the HSD vent was blocked, and he found that the blowhole was unobstructed.

3. The Chinese manual says that obstructing the blowhole would cause the HSD battery to be overheated, thus reduce its output. However, the manual does not mention that it may cause the hybrid controlling unit to be overheated.

4. The manual says that the cooling water of hybrid controlling unit should be examined if this warning appears. But the car's cooling water is full.

5. One of the member of the Prius Club in Taiwan said that his Prius II has suffered similar problem before: the HSD system would be overheated while go mountain climbing, but it could work smoothly in general use. Finally he found out that the problem was the cooling water pump failure, as Firepa said.

 

My friend drove back to Toyota yesterday, but the maintenance staff told him that there was no problem......

 

1. The Chinese manual says that the driver should examine the radiator fans and the coolant. My friend just said that they were both ok, but I can not confirm whether or not the cooling fans was working correctly in that moment.

2. Both of the engine coolant and the power control unit coolant tanks were full. The car just received a regular maintenance on August 6th.

3. It rained a little on the mountain. And the temperature was 32(flat) to 27(mountain) degrees centigrade. Both of the headlights and the air conditioner were on. The traffic was not that heavy, but while climbing toward the mountaintop, my friend encountered a traffic control. After idling for 5 minutes, the HSD battery ran out of power, and he turned the power off. When the traffic control finished, he restarted the car, turned on the air conditioner and headlights, then drove toward his goal once again. This time after he drove about 1~2 kilometers, the problem occurred.

4. My friend drove his Prius to Toyota today. The technician connected the OBU to a computer, but it did not show any error code. Besides, the inverter cooling water pump was assured being alright too. So the members of the Prius Club are confused that how could this problem burst.