Engine Revs looses power

usually, the engine revving going down a steep grade means the battery won't hold anymore charge, and the engine is used to burn off the excess regenerated electricity.
what do you mean by looses power and won't change into any gear, can you elaborate?

 

Sometimes when the hybrid battery is full while you are going down a steep hill, no more regen braking (wheels driving generator) is available. At that point the system goes into an engine braking situation allowing the wheels to rev up the engine with fuel and spark off. That provides slowing force. It saves the hydraulic brakes and is similar to the B mode.

When the steep grade is over it should revert to normal hybrid mode, eg engine, ev or both.

What happens if you don’t come to a complete stop, shutdown and restart?

 

gotta admit I'm confused... if you're going down a steep grade, why would you be using power? How would you know you were losing any?

It's normal for a Prius engine to rev high while going down a grade, unless you give it some pedal. Those revs are how it burns off energy once the battery is full.

 

Check the battery graphic when it does this. See if it is fuller than normal.

Don’t use the B mode.

 

it sounds like you're not getting gas after the engine has been used to burn off electrons. but it's just a guess and i don't know why it is behaving like that. tough with no codes.

 

i thought they stayed until erased. did you get any trouble lights on the dash?