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Fig 1: Identifying Dipped Beam Communication Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fig 2: Identifying Dipped Beam Circuit Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.

This function activates the dipped beam when the car key is taken out of the ignition switch, the driver's door is opened and the dipswitch is moved to its rearmost position "flash". If the driver's door is closed at any time within the next 30 seconds the dipped beam comes on for a preprogrammed duration.

The point of "FOLLOW ME HOME  " is that the car's dipped beam is used when no light sources are available other than those on the car. The car's dipped-beam function remains active for a certain time after the car key is withdrawn from the ignition switch and the driver's door is closed. The duration is programmable in DICE (20--50 seconds).

A number of conditions must be fulfilled before DICE will activate this function.

DICE uses pin 7 to detect that the key has been withdrawn from the ignition switch. DICE then needs to get a message from TWICE concerning the status of the driver's door (OPEN). When the dipswitch (215) is activated, power is supplied to pin 41 on DICE.

The last precondition is fulfilled when TWICE puts a message on the bus concerning the status of the driver's door (CLOSED). The dipped-beam relay is thereupon grounded via pin 4 on DICE for a pre-set time (20--50 seconds), causing the dipped-beam lamps to light up.