Turn Signals: Description and Operation

GF82.10-P-3008SX Turn Signal Indicator Actuation, Function

Component Identification:

Turn signals
Function requirements:
^ Circuit 5R On

Function
The steering column module detects the position of the turn signal switch and transmits the request over the chassis CAN to the central gateway control unit, which then forwards it over the interior CAN to the rear SAM control unit.
The rear SAM control unit is the master control unit for all turn signal functions and it transmits the requests as a flashing cycle over the interior CAN to the corresponding control units.

Left turn signal
The front SAM control unit actuates the turn signal lamp in the left front lamp unit (E1).
The left door control unit actuates the left outside mirror turn signal lamp.
The rear SAM control unit actuates the turn signal lamp in the left taillamp (E3).

Right turn signal
The front SAM control unit actuates the turn signal lamp in the right front lamp unit (E2).
The right door control unit actuates the right outside mirror turn signal lamp.
The rear SAM control unit actuates the turn signal light in the right taillamp (E4).

Feedback
The activated function is notified to the instrument cluster by the central gateway control unit over the central CAN. The instrument cluster actuates the corresponding indicator lamp and the turn signal indicator.
If a turn signal light or turn signal lamp fails, then only the flashing frequency of the respective indicator lamp doubles.

End flashing action
The turn signal procedure is terminated through automatic reset by turning back the steering wheel or manually resetting the turn signal switch.

One-touch turn signaling
The operational sequence for the turn signal lamp touch control is the same, in relation to the signal flow, as that for the turn signal indicator. The difference lies in the triggering and ending of the turn signal procedure.
For one-touch turn signaling mode the turn signal indicator switch should only be briefly moved (approx. 0.5 ms) into the desired signaling position. Without the turn signal switch engaging into place in the signaling position, a sequence of three turn-signal cycles is triggered.
One-touch turn signaling is ended by triggering of the hazard warning flasher function or by operating the turn signal indicate switch in the opposite direction.

Vehicles with code (550) Trailer hitch
The "turn signal" request is transmitted by the rear SAM control unit over the interior CAN to the trailer recognition control unit. The trailer recognition control unit actuates the trailer hitch socket accordingly.

Hazard warning flashers
Function requirements:
^ Circuit 30

Function
The status of the hazard warning system button is detected by the upper control panel control unit and forwarded over the interior CAN to the rear SAM control unit. The rear SAM control unit forwards the request as a flashing cycle over the interior CAN to the corresponding control units.
^ The front SAM control unit actuates the turn signal lights in the front lamp units.
^ The left door control unit actuates the left outside mirror turn signal lamp.
^ The right door control unit actuates the right outside mirror turn signal lamp.
^ The rear SAM control unit actuates the turn signal lights in the taillamps.

Feedback
The active hazard warning flasher function is displayed by the turn signal indicator in the instrument cluster and additionally, after the rear SAM control unit has set the "hazard warning flasher active" status, by the indicator lamp in the hazard warning system button.

With circuit 15R On, the indicator lamps in the instrument cluster are additionally actuated.

Hazard warning flasher in event of crash
In the event of a crash (acceleration > 4 g), the request is transmitted by the restraint systems control unit over the chassis CAN to the central gateway control unit.

It is then forwarded by the central gateway control unit over the interior CAN to the rear SAM control unit which activates the hazard warning flasher function.
The hazard warning flasher function is deactivated by pressing the hazard warning system button in the front central operating unit.

Vehicles with code (550) Trailer hitch
The request is transmitted by the rear SAM control unit over the interior CAN to the trailer recognition control unit. The trailer recognition control unit actuates the trailer hitch socket accordingly.