Occasional high pitch chirp when accelerating between 25-30mph *video*

Glad to be of help! I've been searching for pretty much a year to find the cause of this rattle, as it drove me nuts at times. As my 'technical knocks' on the dash didn't work, I searched google and youtube and that video popped up. There is also a thread on priuschat too about this issue:

Chirping/Electrical Noise? | PriusChat

Edit: The conditions for me, when this rattle occured were:
- Usually after 20 minutes or so.
- When accelerating, or cruising at around 65mph, it disappeard when releasing the gas pedal
- It got worse and lengthier when the temperatures outside went up, spring, summer. Also when driving in strong headwinds.

I still have a recorded video of my own on this rattle. I will upload it to youtube tonight and post it here.

I had my mechanic read the comments on this video and have him hear my own recorded video on this noise. He agreed it was the same and gave the coolant lines and clamp a look. Took some isolation material, put that around the screw that connects the clamp to the 'inner wall' and made sure everything was fastened correctly. In the beforementioned topic about this rattle the solution was to reroute the coulant lines. My mechanic wanted to try the quick solution first (can't blame him).

Never heard that noise again.

Edit 2: Now that I think about it, I believe it was the clamp of the coulant lines that rattled against that inner wall where its fastend to. It's the area behind the motor, pretty much in the middle of the engine bay that you/the mechanic should be looking into.

 

My 2014 suffers same noise. Thanks for the "isolation" tip!