Gas engine working, electric motor not working

If there was a drivetrain problem, you would have warning lights in the display. What makes you think there's a problem?

 

what is a brake vent? is it hot in arkansas?

 

If the car moves, the electric motor is working. That is how the Prius works. Now, if the car isn't going into EV mode, that means the conditions aren't just right for it to activate. EV only works when certain conditions are met. If you're not getting any warning lights, you should be ok.

 

how are the mpg's?

 

Car can't move without both electric motors working.

 

As others have said, if the car is running and there are no lights on the dash then the motors are ok. Here is something that you can do to convince yourself though - put the car in reverse. If you can back up then the motor is fine - reverse is not powered by gas, only the electric motor.

It does sound like you have an issue with the vent in the back. Keeping this clear and functioning is very important. If the hybrid battery overheats you can have problems like you mention in your first post.

 

Does the dashboard give you an error message when you press the EV button? It so, what does the message say?

EV mode has several restrictions, including minimum battery SOC, minimum engine coolant temperature, maximum traction battery temperature, maximum speed (which varies with temperature), maximum power or acceleration, and probably some more that I can't remember.

When EV is locked out by by high battery temperature, MPG also suffers. Is your car baking in the sun during a heat wave? A blocked battery cooling vent also contributes this is. Some readers have also reported loud fan noise from this vent when hot. If the battery is hot but the fan noise is absent, that could also suggest fan malfunction.

 

I had this happen to me twice when I was using the car hard on a hot day. I think the battery must have got too hot and the car tried to avoid using it by running the engine with only minimal EV use. In fact the engine was revving at about 2,000 rpm all the time. No error messages and this was only temporary and stopped when I gave the car a rest.

I didn't hear any HV battery fan either.