A multi-voltage electrical system of a motor vehicle includes first and second subsystems operable at operating voltages, where a current is selectively and alternatively feedable from the first subsystem into the second subsystem and from the second subsystem into the first subsystem, and an electrical consumer is coupleable to and decoupleable from the first subsystem. A method for operating the system includes, responsive to a failure or lack of an attenuator, implementing a special operating mode in which negative and positive sudden load variations caused by coupling or decoupling of the electrical consumer is counteracted by, respectively, feeding current from the second subsystem into the first subsystem or vice versa, in each case over a respective feed time period.