Remove/install control unit of seat belt warning/road speed warning - ra54001402312x(2312)

Model 140 - A./B. Remove/instal up to 05/96, as of 06/96 C. Function of N2/4 (only USA to 05/96), D. Function of N2/3 (only SA to 05/96) 

Operation no. of operation texts and work units or standard texts and flat rates:

1. Removal, installation up to approx. 05/96 

   Preliminary work:

   Instrument cluster removed (Removal and installation of the instrument cluster  ).

   Fig 1: Identifying Road Speed Warning Control Unit, Seat Belt Warning Control Module, Electrical Connection And Bolt

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
   NOTE: The seat belt and vehicle speed warning control module (N2/4) , seat belt warning control module (N2/4) is installed on vehicles with the previous instrument cluster. Identification: When the door is opened the instrument cluster display does not come on. 

   Ground cable at battery	disconnect, connect.
   Bolt (1)	unscrew, screw in.
   Electrical connection (2)	unplug, plug in.
   Seat belt and road speed warning control unit (N2/3) or seat belt reminder control	remove, insert.
   unit (N2/4)

2. Removal, installation as of approx. 06/96 

   Preliminary work:

   Instrument cluster removed (Removal and installation of the instrument cluster  )

   NOTE: The seat belt and vehicle speed warning control module (N2/4) , or seat belt warning control module (N2/4) has been eliminated on all vehicles with the new instrument cluster. This function is now accomplished by the instrument cluster. Identification: When doors are opened the display on the new instrument cluster comes on.

   Programming can be accomplished with the HHT, see Diagnosis Manual.

   Instrument cluster install.

3. Function, seat belt warning control module (N2/4) up to approx. 05/96 

   The seat belt warning control module (N2/4) has three functions 

   1. Warning signal when seat belt is not buckled 

      When the ignition is switched on and the left front door closed (door switch S17/3 open) and the driver's seat belt is not buckled, a warning tone sounds for 4-8 seconds. When the seat belt is buckled the seat belt buckle switch (S68/1) interrupts the circuit and the warning buzzer is switched off.

      Seat belt reminder lamp 

      The seat belt reminder lamp (A1E9) is installed in the instrument cluster (A1) as a reminder to buckle the seat belt. After starting the engine it flashes for approx. 5 sec regardless of whether the seat belt is buckled or not. The reminder lamp is controlled via circuit 15 and the electronic circuitry in the instrument cluster (A1).

   2. Warning when door is open 

      When the left front door is open (door switch S17/3 closed) and the key is not removed from the ignition lock, the seat belt warning control module (N2/4) actuates the warning buzzer via circuit 15C of the ignition/starter switch and a continuous warning tone sounds.

   3. Warning that lights are not switched off 

      When the key is removed from the ignition lock with the high beams, low beams or parking lamps switched on, a warning buzzer sounds when the left front door is opened. The warning buzzer is actuated via fuse 1 circuit 58R to the rotary light switch circuit 30 input, output circuit K to the seat belt warning control module (N2/4).

4. Function of seat belt and vehicle speed warning control module N2/3 

   up to approx. 05/96 

   The seat belt and vehicle speed warning control module N2/3 contains 2 functions 

   1. Warning if seat belt not fastened 

      If the driver does not fasten the seat belt when the key is in position 2 in the steering lock, a warning signal sounds for 4-12 seconds. The seat belt buckle switch (S68/1) interrupts the circuit when the seat belt is fastened and the warning buzzer is switched off.

      Seat belt reminder lamp 

      The seat belt reminder lamp (A1e9) is installed in the instrument cluster (A1) as a reminder to buckle the seat belt. It flashes after the engine is started for approx. 5 seconds regardless of whether or not the seat belt is buckled. The lamp is activated via terminal 15 by the instrument cluster (A1) electronic circuitry.

   2. Speed warning 

      If a speed of 120-130 km/h is exceeded, an audible alarm signal sounds. The seat belt and vehicle speed warning control module (N2/3) is actuated via the connector (A2x1, radio/speed signal connector, 1-pin), terminal 15 in the fuse and relay box (F1) fuse 5 and the main ground (W1), behind the instrument cluster (A1).