Abstract: A vehicle includes a brake pedal, a master cylinder, a braking circuit with a wheel cylinder, and a brake pressure generator with strokable piston. A pedal feel simulator is coupled to the master cylinder through a switchable valve, the simulator providing a reaction force. An isolation valve closes to isolate the braking circuit from the master cylinder and the simulator circuit. A controller is programmed to place the simulator in fluid communication with an output of the brake pressure generator, and to stroke the piston at a designated diagnostic time. The resulting pressure increase is observed, and the controller checks whether the pressure-increase to piston-stroke relationship is within a predetermined acceptable range for continued operation of a brake-by-wire mode in which the master cylinder is coupled to the simulator circuit and decoupled from the braking circuit.

Abstract: A vehicle includes a brake pedal, a master cylinder, a braking circuit with a wheel cylinder, and a brake pressure generator with strokable piston. A pedal feel simulator is coupled to the master cylinder through a switchable valve, the simulator providing a reaction force. An isolation valve closes to isolate the braking circuit from the master cylinder and the simulator circuit. A controller is programmed to connect the simulator circuit with an outlet of the brake pressure generator, and to stroke and retract the piston at a designated diagnostic time. The controller observes a pressure decrease as the piston retracts and checks whether the pressure-decrease to piston-retraction relationship is within a predetermined acceptable range for continued operation of a brake-by-wire mode in which the master cylinder is coupled to the simulator circuit and decoupled from the braking circuit.

Abstract: A vehicle includes a brake pedal, a master cylinder, a braking circuit with a wheel cylinder, and a brake pressure generator. A pedal feel simulator is coupled to the master cylinder through a switchable valve. An isolation valve is provided to isolate the braking circuit from the master cylinder and the simulator circuit. A controller is programmed to couple the simulator circuit to a pressure sensor positioned in the braking circuit at a designated diagnostic time during which the brake pedal is depressed to generate a brake pedal input while the vehicle is positively parked. Increased fluid pressure from the brake pedal input is observed with the sensor in the braking circuit. The controller checks whether the pressure-increase to brake pedal input relationship indicates efficacy of the simulator circuit for continued operation of brake-by-wire operation.

Abstract: A vehicle braking system includes a brake pedal, master cylinder, a braking circuit with a wheel cylinder, and a brake pressure generator. A pedal feel simulator is coupled to the master cylinder output side through a switchable valve, the pedal feel simulator providing a reaction force. An isolation valve closes to isolate the braking circuit from the master cylinder and the simulator circuit. A primary pressure sensor generates a braking request signal responsive to the brake pedal. A controller activates the brake pressure generator to apply a braking force to the wheel cylinder based on the braking request signal. The controller identifies an abnormal value from the primary pressure sensor and couples the pedal feel simulator with a secondary pressure sensor within the braking circuit to determine whether the abnormal value indicates a primary pressure sensor malfunction or a malfunction of the pedal feel simulator or the switchable simulator valve.

Abstract: A vehicle includes a brake pedal, a master cylinder, a braking circuit with a wheel cylinder, and a brake pressure generator with strokable piston. A pedal feel simulator is coupled to the master cylinder through a switchable valve, the simulator providing a reaction force. An isolation valve closes to isolate the braking circuit from the master cylinder and the simulator circuit. A controller is programmed to place the simulator in fluid communication with an output of the brake pressure generator, and to stroke the piston at a designated diagnostic time. The resulting pressure increase is observed, and the controller checks whether the pressure-increase to piston-stroke relationship is within a predetermined acceptable range for continued operation of a brake-by-wire mode in which the master cylinder is coupled to the simulator circuit and decoupled from the braking circuit.

Abstract: A vehicle braking system includes a brake pedal, master cylinder, a braking circuit with a wheel cylinder, and a brake pressure generator. A pedal feel simulator is coupled to the master cylinder output side through a switchable valve, the pedal feel simulator providing a reaction force. An isolation valve closes to isolate the braking circuit from the master cylinder and the simulator circuit. A primary pressure sensor generates a braking request signal responsive to the brake pedal. A controller activates the brake pressure generator to apply a braking force to the wheel cylinder based on the braking request signal. The controller identifies an abnormal value from the primary pressure sensor and couples the pedal feel simulator with a secondary pressure sensor within the braking circuit to determine whether the abnormal value indicates a primary pressure sensor malfunction or a malfunction of the pedal feel simulator or the switchable simulator valve.

Abstract: A vehicle includes a brake pedal, a master cylinder, a braking circuit with a wheel cylinder, and a brake pressure generator with strokable piston. A pedal feel simulator is coupled to the master cylinder through a switchable valve, the simulator providing a reaction force. An isolation valve closes to isolate the braking circuit from the master cylinder and the simulator circuit. A controller is programmed to connect the simulator circuit with an outlet of the brake pressure generator, and to stroke and retract the piston at a designated diagnostic time. The controller observes a pressure decrease as the piston retracts and checks whether the pressure-decrease to piston-retraction relationship is within a predetermined acceptable range for continued operation of a brake-by-wire mode in which the master cylinder is coupled to the simulator circuit and decoupled from the braking circuit.

Abstract: A vehicle includes a brake pedal, a master cylinder, a braking circuit with a wheel cylinder, and a brake pressure generator. A pedal feel simulator is coupled to the master cylinder through a switchable valve. An isolation valve is provided to isolate the braking circuit from the master cylinder and the simulator circuit. A controller is programmed to couple the simulator circuit to a pressure sensor positioned in the braking circuit at a designated diagnostic time during which the brake pedal is depressed to generate a brake pedal input while the vehicle is positively parked. Increased fluid pressure from the brake pedal input is observed with the sensor in the braking circuit. The controller checks whether the pressure-increase to brake pedal input relationship indicates efficacy of the simulator circuit for continued operation of brake-by-wire operation.