Method and apparatus for controlling the operating temperature of an internal combustion engine

Method for regulating the operating temperature of an internal combustion engine (1) in which a cooling liquid in a circuit through the internal combustion engine (1) driven by one of a pump motor (7), pump (2) is transported, the temperature of the cooling fluid is measured, and the pump motor (7) is controlled by a control device (5) in dependence on the temperature of the cooling liquid by means of a pulsed current with a predetermined switching frequency, characterized in that at a temperature below the normal operating temperature of the coolant of the pump motor (7) and the wherein the respective current pulses of the pulsed current to increase the power loss at an increased switching frequency of a ripple having rising and falling edges is impressed control means (5) loss of heat generated is transferred to the cooling liquid.