Electronic sound when braking and when shifting into reverse/drive

Maintenance/Repairs
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1

Hi everyone, my 2009 Prius makes a sound similar to what I can best describe as an old computer struggling to complete a task when I either hit the brake or shift into drive or reverse. The sound is not constant, it happens when I begin moving always and when I slow down almost to a stop but never at speed. What could this be? Thank you.

2

Any dash lights light up when this happens? And dash warning lights on all the time? Check engine light? How many miles on this thing?

3

How long have you owned this Prius?
If you have owned it for a long time, is this noise a new phenomenon?

If you haven’t owned it for the long term, I am wondering if the noise that you hear when braking is the result of the car’s regenerative braking system being activated.

1 Like
4

The hydraulic brake pump is noisy. With the vehicle in park, apply the brake several times to see if you can replicate the noise.

5

Any other way you can describe the sound? I’m retired software engineer, been programming them since 1961, but I’ve never heard one “struggling to complete a task.” I’ve heard fan noise (hear it now on my desktop computer) and disk heads moving. I’ve also heard tape drives moving back and forth.

6

I miss the sound (and visual ) of 9 track tape drives on a 390.

7

Hi, I have 109,000 miles on this car. It only makes the noise occasionally. Has no codes shown and I seen a video making a similar sound to this and the video owner commenting saying it was the brake actuator. I’m wondering if that’s what I should be worried about though.

8

If the brake booster pump cycles on/off frequently without cause there may be a leak in the booster/accumulator assembly. To identify the source of the noise you will need to show someone what you are listening to.

There was a safety recall issued in 2013 to inspect/replace the brake booster pump assembly w/accumulator, if your vehicle has been to a dealer in the last 7 years this most likely has been completed.

There was a customer support program (warranty extension) to cover the brake booster pump assembly w/accumulator issued last year however it expires after 10 years from the date of first use or 150,000 miles.