Mercedes Benz 171 OverHead Control Unit

· 1 Dome lamp ON and OFF switch
· 2 Door contact ON and OFF switch
· 3 Left reading lamp switch
· 4 Right reading lamp switch
· 5 Interior lights
· 6 SOS pushbutton switch (code 359)
· 7 Garage door opener button (code 231)
· 8 Garage door opener indicator lamp (code 231)
· 9 Left reading lamp (code 876)
· 10 Right reading lamp (code 876)
The overhead control panel control unit reads sensors and switches and controls their functions. Depending on the requests received, consumers are switched or supplied with voltage and signals are transmitted or received via CAN-B.
Control
• Master control unit for interior illumination
• Exit lamps (code 876)
• Footwell lamps (code 876)
Special functions
• Windshield wiper startup suppression
• OFF delay function of interior lights
• Dimming function of inside rearview mirror and driver-side outside mirror (code 249)
Note
The special functions are not necessarily controlled by the overhead control panel, they may just be indirectly associated with the overhead control panel.
• Inside rearview mirror unit (code 876)
• Inside rearview mirror unit
• Rain/light sensor (code 345)
• Interior protection transmitter and receiver (code 882)
• Left front vanity mirror illumination (code 876)
• Right front vanity mirror illumination (code 876)
• Door contact ON and OFF switch
• Dome lamp ON and OFF switch
• Left reading lamp switch
• Right reading lamp switch
• Vario roof "closed" limit switch (left pin)
• Rain/light sensor (code 345)
• Automatic dimming interior rearview mirror sensor, forward (code 249)
• Automatic dimming interior rearview mirror sensor, back (code 249)
• Interior protection transmitter and receiver (code 882)
• Inside rearview mirror unit (code 249)
• Rain/light sensor (code 345)
The overhead control panel control unit is a CAN-B subscriber in the overall network.
On vehicles without code 876, the left and right reading lamps are not installed on the underside of the inside rearview mirror unit but directly in the overhead control panel control unit. They are nevertheless actuated in the same way as on vehicles with code 876.
Dome lamp ON and OFF switch (1) Interior lights (5)
Pressing the dome lamp ON and OFF switch (1) switches the left and right front interior illumination (5) in the overhead control panel on or off.
Door contact ON and OFF switch (2)
Pressing the door contact ON and OFF switch (2) causes it to engage further in, which deactivates the automatic control for the interior illumination.
Pressing the door contact ON and OFF switch (2) again causes it to disengage so that it is flush with the other switches. This reactivates the automatic control for the interior illumination.
The automatic interior illumination is switched on when
• The vehicle is unlocked
• The transmitter key is removed from the ignition lock
• A door is opened
On vehicles with code 876, the automatic interior illumination only switches on in darkness.
The interior illumination switches back off after a delay.
Left reading lamp switch (3) Left reading lamp (code 876) (9)
Pressing the left reading lamp switch (3) switches the left reading lamp (9) on the underside of the inside rearview mirror unit on or off.
Right reading lamp switch (4) Right reading lamp (code 876) (10)
Pressing the right reading lamp switch (4) switches the right reading lamp (10) on the underside of the inside rearview mirror unit on or off.
SOS pushbutton switch (6) (code 359)
Pressing the SOS pushbutton switch (6) transmits an emergency call manually. An LED in the SOS pushbutton switch (6) flashes to indicate that an emergency call has been activated.
Note
The SOS pushbutton switch is integrated in the overhead control panel control unit but is read discretely by the emergency call system control unit (code 359).
Garage door opener button (7) (code 231) Garage door opener indicator lamp (8) (code 231)
To actuate the garage door opener, circuit 15R must be switched on and the corresponding garage door opener button (7) must be programmed for the relevant garage door.
Pressing one of the garage door opener buttons (7) opens or closes the garage door.
The transmitter transmits for as long as one of the garage door opener buttons (7) is pressed.
After a maximum of 20 seconds, the transmission is aborted and the garage door opener indicator lamp (8) flashes. Pressing the button again reactivates the transmission.
• For garage door systems with fixed code:
The garage door opener indicator lamp lights up permanently.
• For garage door systems with variable code:
The indicator lamp flashes briefly and then lights up for approx. two seconds. This is repeated for up to 20 seconds.
· 3 Power supply to vanity mirror illumination
· 4 Vanity mirror illumination ON/OFF
· 5 Alarm signal
· 6 Reading lamp ON/OFF
· 7 Rain detected
· 8 Darkness detected
· 9 Dimming information
· 10 Reverse gear engaged or interior lights switched on
· 14 Emergency call active
· 15 Emergency call signal
· 17 Power supply to rain/light sensor
· 19 Vario roof closed
· 20 Interior protection active
· 26r Power supply to inside rearview mirror unit
· 27 Interior protection voltage supply

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