Halogen headlamps
The light switch (10) is connected to BCM. When the switch is in position 2, BCM sends the bus message "Dipped beam button active ON". The dipswitch is integrated in CIM. When it is moved to its rear position (2), CIM sends the bus message "Main beam, stalk active ON".
The bus message "Main beam, stalk active ON" is used by UEC, which lights main beam by supplying B+ voltage from control module pins 17 and 21 to pin 2 of the headlamps while the outputs for dipped beam are active. Each headlamp is grounded in the body on pin 1.
BCM receives the bus message "Main beam, stalk active ON" and sends the bus message "Main beam indicator active ON" to MIU (540). MIU lights the lamp (47g) that indicates that main beam is lit.
While the ignition key is turned to the START position (+50), main beam is off. Main beam lights again once the engine has started or once the ignition key has been turned to the ON position.