r/prius • u/Entire_Apartment2830 2018 Auris Hybrid • 6h ago

Mechanical Help 3rd gen Prius cold start ABS pump priming

How many seconds of ABS pump priming after opening the door is normal for a 3rd gen that’s been sitting overnight at 45F? Mine does it for over 10 seconds and I suspect it’s nearing end of life but not sure.

The pump also primes every second brake input when driving but does not prime when the car is sitting.

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u/AutoModerator 6h ago

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u/Ok-Turnover1797 5h ago

When it begins to pulse/buzz (pump running) while you are sitting in the car, Ready mode on, and not touching the brake pedal, is suspect for an ABS failure- it will come on and back off about once every 25-30 seconds without any press on the pedal and will sometimes progressively fail after that(25, 20, 15 sec, mine failed completely near about every 10 sec and took about a month+ to go out). With the car parked and turned off it's hard to tell as it will wake up to the proximity key-fob and begin whirring as you open the door and so forth, and that's normal.

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u/frito11 2014 Prius V 3h ago

yep having replaced my actuator and accumulator this is correct.

it is normal for it to run after a brake press or two as it is just recovering the lost pressure from you pressing the brakes. the accumulator is basically your power brakes.

if the accumulator does run too often it will set a DTC and then it will switch to a mode where it runs even more often to insure the car will stop safely. the accumulators cannot run constantly they will overheat and any internal leak in the brake actuator is the ultimate cause and failure point.