Brakes sounds like air pressure pumps

07 Prius 140k miles. Flushed brakes at 132k miles with techstream directions (http://auser107.com/wp-content/uploads/2014/10/Brake-Bleed-TIS.pdf). Follow the path without actuator or master cylinder removal. Went smoothly, no funny noises or codes after.

Brakes making multiple clicking / pump type of noise within last couple of months under these situations.

1. when nearing a stop
2. crawling along slowly with brakes on
3. backing up which is like #2

Braking force is fine and linear response. Brake fluid reservoir level is good.

Thoughts? I'm thinking flushing it again.

 

Stilling chasing this problem. Techstream tests shows everything seems to be normal. Accumulator doesn't leak pressure, pressure at all 4 wheels good. No codes.

Considering bleeding the actuator to ensure no air trapped in that part of the circuit. Factory directions have a couple of unclear spots on when to remove+install the 2 motor relays. Here are the directions

http://techno-fandom.org/~hobbit/cars/TIS/ileaf/04toyrm/04toypdf/04rmsour/2004/04priusf/32/219qc/f040001.pdf

Here are the 2 confusing points. Just want to clarify before doing this.

Step 5(b) removes the 2 relays, 5(c) says go to step 4 to bleed FR FL. I think the sequence is 4(b), don't do 4(c) and return to 5(d). Relays don't get reinstalled until 5(f).

Step 5(l)(2) says to bleed the FL, I assuming this means 2 relays come out, bleed FL and relays goes back on before continue to 5(m)?