Method of operating a throttle-valve adjustment device

A method of operating a displacement device for the throttle valve of an internal combustion engine of a motor vehicle, wherein the displacement device permits a displacement of the throttle valve in the opening direction, alternatively, by a gas pedal and by an electromotive setting drive against the force of a return spring, wherein the displacement device includes a first potentiometer to provide a first signal representing the position of the throttle valve and a second potentiometer to provide a second signal representing the position of the setting drive, the displacement device having an electronic control device to process the first and the second signals for controlling the setting drive;

• the method comprising the steps of:
• periodically testing the functionality of the first and the second potentiometers at predeterminable time intervals, said testing being accomplished by displacing the setting drive from its instantaneous position at least once in the direction of a closing of the throttle valve and back into the instantaneous position upon a location of the throttle valve in a setting region above the maximum idling position;
• and
• evaluating from movements in like direction of the setting drive and the throttle valve as to the presence of an error in one of said first and said second potentiometer signals.