Stepper Motors

Purpose and Operation
Stepper motors are installed in order to move the various flaps. The control unit assumes that, after completing the calibration phase, the stepper motors are in a defined position since the stepper motors cannot signal back their position to the control unit. The calibration phase is triggered when the power supply (terminal 30) of the control unit was interrupted or after the ignition was deactivated 10 times. The calibration phase is then started after ignition "ON". Error detection differentiates between short to positive, short to negative and a break in the circuit. If the control unit detects a stepper motor defect, the defective motor is no longer activated. The stepper motors no longer move if the voltage of the vehicle electrical system drops below 9V or increases above 15V. The stepper motors operate with only half frequency when the voltage of the vehicle electrical system is between 9V and 11V.