My Prius makes that noise. It's related to the ABS system.

It may be indicative of an ABS actuator failure; however, mine has been doing it for the last 25K miles with no change. Temperature seems to have an effect as well.

 

I figured it had something to do with the brakes. Anybody know how hard it is to replace? Found a used one with 91k miles for $100.

 

Can anyone confirm that it is the ABS actuator? It doesn’t seem to affect the usability of the vehicle, but I would hate for it to catastrophically fail at some point in the future.

 

ABS actuator would have thrown Christmas lights on the dash.
I am not sure exactly what that sound was, sorry, phone recordings are not the best.
You say this happens exactly when brakes are applied?
1. engine mounts
2. control arm bushings
3. not really but maybe bad CV joint.
4. gods save, brake pads move on bracket or entire caliper assey is loose.
Truly you need to get car up on lift, arm yourself with yard long pry bar and move everything underneath with it.

 

Cranked volume up.
You seriously need to get her up on lift and investigate from the bottom. Sounds like something is jerking tuck-tuck... Right?

 

I've driven 50+ Priuses that have those brake sounds.

It is the ABS actuator.

It is not a sign of impending failure as they can make this noise for tens of thousands of miles (both of mine for the last 25K miles each).

It takes an actual FAILURE before codes are thrown.

 

It occurs whether at a dead stop or moving. It Can sometimes be repetitive, like thunk, thunk, thunk, thunk, several times, not just once from some large part shifting position. Even happens occasionally multiple times while stopped, before moving selector from park. I’m leaning towards it being the ABS module. It definitely seems like it is getting more frequent. If I buy another module from a lower mileage HiHy or RX400h, how do I replace it? Is it in the engine compartment or underneath or is it hidden somewhere more of a pain in the butt, like inside the transmission or something? Thanks!

 

ever found out what it was?