2006 Squealing noise on start up and shut down

Has anyone tried putting it in Ready, opening the hood and listening while the engine comes on and turns off to hear about where the sound is coming from? How about the water pump belt on the engine? Has it been replaced recently? Is it tensioned properly? (Do not check that with fingers while in Ready mode.) Has the engine compartment been washed lately? When did the squealing start? What changed on the car just before it started? Did it start all at once or gradually? Does it happen everytime the engine starts and stops or everytime you push the Start/Stop button? The more details you can think of about the conditions surrounding the sound the more we have to work with.

Does it sound like a small electric motor running for a few seconds?

 

You should inquire to Toyota about getting reimbursed for the inverter pump as it is under recall.

 

The inverter pump runs all the time that the Prius is READY so it is highly unlikely that was the cause of the noise reported in your subject.

A sound produced only upon startup and shutdown is probably produced by the coolant heat recovery pump, located in the driver's side wheel well. Unless you have the check engine warning light on, you don't need to worry about replacing the pump - unless you dislike the sound so much that you are willing to spend money to get rid of it.

 

Ok, found out it's the "coolant heat storage water pump." It's in the drivers front wheel well. It was not the inverter pump. It's anywhere from $75 used to $140 online to $175 at the dealer. Doesn't sound like anyone wants to put it in and if they do they want $600+ (and no kisses). Anybody attempted to do this themselves. ALLDATA repair scares me with the battery diffusing and insulated gloves. Come on....it's 3 bolts, 2 hoses and 1 electrical connection. How hard can it be?? Anybody been toasted? Is it a PITA? Momma hates it and thinks it'll strand us on vacay to Canada. Any info helpful!

 

^^^
There was a TSB at Attention: If you have a squeaky CHS water pump! New TSB | PriusChat. I had my squealing CHS pump (pumps coolant into and out of thermos) replaced under warranty via this TSB long ago. Unfortunately, you're almost certainly out of powertrain warranty, as I am.

 

Not very hard. There is no shock hazard there.

However, if the only problem you have is that the pump is noisy, you don't need to worry about it. Most likely, the pump will continue to operate indefinitely and just make noise.

Worst case, the pump fails and the check engine light turns on, but this will not affect the powertrain reliability or performance. All that will happen is that the engine will emit slightly more emissions during its warmup cycle.