The disclosure relates to controlling braking behaviors a vehicle in an autonomous driving mode in the event of a hydraulic system failure. For instance, the vehicle may be controlled in the autonomous driving mode according to a first braking control behavior based on a first relationship between position of a brake pedal of the vehicle and amount of deceleration for the vehicle. While controlling the vehicle, a failure of a hydraulic system may be determined. Based on the determination, the vehicle may be controlled in the autonomous driving mode according to a second braking control behavior by moving the brake pedal until the vehicle reaches a deceleration target defined by the second braking control behavior.