Can a failed brake booster (or vacuum pump) cause a slowly sinking-to-floor brake pedal under sustained pedal pressure (with engine on only), and in detail, how? Assuming brakes otherwise work normally. -
How can an ABS unit cause a slowly sinking brake pedal (with engine running)? Does it mean there is air in the accumulator and the master cylinder is slowly drained into it?
![Got these codes. When I go into drive the brake pedal sinks to the floor. How screwed am i? : r/prius Got these codes. When I go into drive the brake pedal sinks to the floor. How screwed am i? : r/prius](https://external-preview.redd.it/d8HdLmrv83nRaxd9iajlqZdVvVrMXoihTqmNqyr6c94.png?width=640&crop=smart&auto=webp&s=3914932d7947458b5923ca5a75a8214501cad7f8)