Mysterious Faint and Intermittent Squeak/Whining Noise from Front Driver's Side

Others will have better details, but it's likely the dash or the triangle piece on the A-pillar.

 

The screw holes on the underside of the exterior mirror?

 

bllockwood,

:welcome: to PriusChat.

I can't say with certainty what the noise is that you're hearing. I take
it though that you are aware that the Prius makes all kinds of unusual
sounds that are a liitle scary at first to new drivers, but are in fact
normal for this car.

So, I'm going to do a little speculating here, with the hope that one of
the longer term owners comes up and sets us both straight.

If the noise occurs at all the times you report, it can't be associated
with any of the mechanical or electrical systems that directly move or
stop the car, or are connected with the air co system.

This then suggests overhead functions such as the DC to DC converter
that keeps the 12v battery charged; it is under the hood right in front
of the driver's seat.

Or, perhaps the mechanical brake system accumulator which needs to
be kept charged nearly to full in the event the HSD fails at speed and
you need to stop the car right now. IIRC, this accumulator is actually a
capacitor array under the floor in the back, next to the 12v battery. I
don't recall what voltage this system needs, but I presume it is kept
charged via the DC to DC converter.

A third, remote possibility is the hot water thermos in the cooling
system. IIRC, whenever the appropriate electronic control unit (ecu)
detects the coolant in the thermos is cooler than the coolant in the
engine-radiator, coolant is circulated (pumped?) through the thermos
to keep it at the highest available temperature. Coolant is also
circulated -- for sure pumped at this time -- when you shut the ICE
down. But I suspect you've already heard this noise and it is not the
one you're asking about.

Let's see if smarter, more experienced posters come up on your
question.

 

Sorry, I missed the bit where you said it occurs when stopped.

 

Well, we haven't really established what the noise is yet. However,
unless it has a grating, grinding, gurgling, or crunching sound, it's
probably normal... for a Prius.

Just for the fun of it, sit in your car for about 10 minutes after you shut
it down. There's a whole gamut of subtle sounds that will occur at random
times that indicate mysterious goings on in the HSD that are completely
normal, but unknown/unsuspected by most all Prius drivers who
immediately exit the car.

Have fun with your Prius, it's a great little car. :cheer2: