Turn Signals: Description and Operation

GF82.10-P-3008SK Turn Signal Lamp Actuation, Function

Component Identification:

The rear SAM control unit with fuse and relay module (N10/2) is turn signal master, in other words it specifies, when and which turn signal lamp is switched on or off. The following priorities apply to the turn signal actuation, corresponding to their sequence:
^ Airbag deployment if the acceleration is > 4 g
^ Anti-theft alarm system (ATA) alarm
^ Turn signal indicator lamps and hazard warning flasher
^ Opening/closing

The turn signal indicator lamps function consists of the following functions:
^ Turn signaling
^ One-touch turn signaling

Function of turn signal indicator lamps
Function requirements:
^ Circuit 15R ON
^ Combination switch (S4) operated to the left or right for t > 500 ms

Turn signal indicator lamps are actuated upon a request from the steering column module (N80). The steering column module (N80) reads in the combination switch (S4) via a local interconnect network (LIN) bus and supplies the signal on the Controller Area Network Bus Class B (interior) (CAN-B). The rear SAM control unit with fuse and relay module (N10/2) receives the message and actuates the left turn signal lamp (E3e1) or the right turn signal lamp (E4e1) via discrete wiring.

The left door control unit (N69/1) actuates the left outside mirror turn signal lamp (E6/5).
The right door control unit (N69/2) actuates the right outside mirror turn signal lamp (E6/6). The driver-side SAM control unit with fuse and relay module (N10/1) either actuates the left turn signal lamp (E1e5) or the right turn signal lamp (E2e5) via discrete wiring. The turn signal frequency is 1.5 Hz with a duty cycle from bright to dark of 52 % to 48 %, which is pulsed by the rear SAM control unit with fuse and relay module (N10/2) and supplied cyclically on CAN-B. The bright turn signal phase is fully completed by the combination switch (S4) if the request is discontinued (S4). If the failure of a turn signal indicator is detected, the frequency of the left turn signal indicator lamp (A1e1) or right turn signal indicator lamp (A1e2) in the instrument cluster (A1) is doubled.

One-touch turn signaling
Function requirements:
^ Circuit 15R ON
^ Combination switch (S4) operated to the left or right for t < 500 ms

The one-touch turn signaling function is actuated upon a request from the steering column module (N80). The steering column module (N80) reads in the combination switch (S4) via the local interconnect network (LIN) bus and supplies the signal over CAN-B. If the combination switch (S4) is actuated for t < 500 ms, the rear SAM control unit with fuse and relay module (N10/2) issues 3 flash cycles. The process is only interrupted in the event of a "hazard warning flasher" request by pressing the hazard warning system switch (N72/1s5) in the upper control panel control unit (N72/1) or by pressing the pushbutton switch in the transmitter key (A8/1) "open/close" via the EIS control unit (N73). Actuating the combination switch (S4) in opposite direction also leads to an abortion. This function can be coded via STAR DIAGNOSIS.