SAAB WIS ONLINE

Brake lights

Brake lights

The brake lights go on when the brake light switch is actuated.

For safety reasons, the brake lights are tested when the ignition is turned ON. The function can be programmed in SID (ON/OFF). When the ignition is turned ON, TWICE sends a bus message. SID makes an acoustic signal and displays TEST BRAKE LIGHTS. The test is confirmed by pressing the brake pedal.



The brake light switch is powered with +30 via fuse 12. When the brake pedal is depressed, the brake light switch (29) closes and pin 48 on TWICE receives current.

The brake lights are powered from pins 1 and 25 via two resistors inside TWICE. The module measures the voltage drop across the two resistors and can in this way determine the current flowing through TWICE to the respective brake light circuits.

In the high-level brake light there are 16 LEDs (30RC) connected in parallel. These are powered and monitored from DICE pin 24. LEDs are used for this function because they light up very much quicker than a normal lamp bulb.

The high-level brake light on the cabriolet has 5 lamp bulbs (30RC) and is monitored from DICE pin 24.

The brake light circuits are prepared for use with a trailer connector. In this case the circuits function in a similar way but they use fuse B (22a).

Filament monitor

In TWICE the current to the respective pins passes through two resistors. In the event of a filament failure error information is send to the bus. SID generates an acoustic signal and displays BRAKE LIGHT FAILURE.