Some 2004-07 Toyota Prius models may produce a squeaking sound when the brake pedal is applied or released.
According to Toyota, the noise is most obvious when the key is in the "ready" mode and the vehicle not moving. A defective brake actuator assembly is the likely cause.
Before replacing the brake actuator, however, try bleeding the braking system. If the noise goes away, you're done with the fix.
If the noise remains after getting out the air, replace the brake actuator with an upgraded unit, part No. 44500-47090.
"Factory Fixes" is written by Jim DePalma, a 30-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via e-mail at [email protected].