Abstract: A microcomputer based electronic control unit for an anti-skid braking system includes monitoring means for testing the correct operation of the anti-skid braking system, including the electronic control unit. The disabling means includes microcomputer resetting means which in the event of program execution falling out of synchronization resets the microcomputer. The monitoring means test whether or not the wheel speed sensors are short circuited or disconnected. The unit also includes a load dump protection function, an electromagnetic interference suppression circuit and a warning light drive which may additionally be used to output diagnostic information.