Method for Operating a Control Unit for a Parking Brake System

A method is for operating a control unit for a parking brake system having a parking brake and a first and a second microcontroller for controlling the parking brake. The first and the second microcontroller are tested one after the other when the system is switched on. Nominal operation of the system is started after the test is ended. The method includes activating the second microcontroller to control the parking brake and deactivating the first microcontroller as a redundancy. When an error occurs in the second microcontroller, the system switches from nominal operation to non-nominal operation in which the first microcontroller takes over the control function of the second microcontroller. During nominal operation, operationally relevant data are transmitted from the second microcontroller to the first microcontroller so that they are available to the first microcontroller in the event of the error.