SOS switch, component description - GF82.95-P-3210SXU

MODEL 221.0 /1 with CODE (494) USA version up to Model Year 8

MODEL 221.0 /1 with CODE (389) Mobile phone preinstallation with universal interface, USA/Canada up to Model Year 8

MODEL 216.3 with CODE (494) USA version up to Model Year 8

Illustrated on model 221

Fig 1: Identifying SOS Push-button Switch

Courtesy of MERCEDES-BENZ USA

Location

The SOS push-button switch is integrated in the overhead control panel control unit (N70).

Task

The following are the primary tasks of the SOS push-button switch:

Actuation of a manual Telematic Alarm Identification on Demand (emergency call system) (TELE AID) emergency call
Visual feedback signal of the TELE AID operating conditions in the event of a manual as well as an automatic emergency call

Design

The SOS push-button switch is designed primarily as follows:

Switch contact
A control resistor in parallel to the switch contact
Cap with inscription "SOS"
Integrated light-emitting diodes (LED) for night illumination (circuit 58d) and to indicate operating condition

Function

In the park position, electric current flows through the control resistor installed in the SOS push-button switch (parallel to switch contact). When current is flowing through the resistor, the emergency call system control unit (N123/4) knows that the voltage supply line and the ground line are functioning properly. When pressing the SOS push-button switch, the control resistor is bridged by a switch contact. The SOS push-button switch is read in by the emergency call system control unit over a discreet line. When the SOS button is pressed, a manual emergency call is recognized by the emergency call system control unit and then transmitted.