Brake light actuation, function - GF82.10-P-3010FL

MODEL 212.0/2 up to 28.2.13 

Function requirements, general 

• No overvoltage or undervoltage (operating voltage range U ≥7 ≤ 17.5 V)
• Circuit 15 ON

The electronic ignition lock control unit (N73) transmits circuit 15 status to the front SAM control unit with fuse and relay module (N10/1) via the interior CAN (CAN B).

Brake light actuation, general 

Corresponding to the request the brake light actuation realizes a static or flashing actuation of the brake lights on the vehicle.

The brake light actuation is comprised of the following subfunctions:

• Function sequence, static brake lights 
• Function sequence, adaptive brake lights 

Function sequence, static brake lights 

The brake light switch (S9/1) is supplied using circuit 15 by the front SAM control unit. When the service brake is operated, the brake lights switch connects the voltage that is present through to the Electronic Stability Program control unit (N30/4) (model 212 (except 212.074/077/095/098/274/277/298) without code (233) DISTRONIC PLUS), the regenerative braking system control unit (N30/6) (model 212.095/098/298) or the Premium Electronic Stability Program control unit (N30/7) (model 212 (except 212.095/098/298) with code (233) DISTRONIC PLUS, model 212.074/077/274/277).

The Electronic Stability Program control unit or the regenerative braking system control unit uses this to generate the "brake lights ON" request and transmits this via the chassis CAN (CAN E), the front SAM control unit and the interior CAN to the rear SAM control unit with fuse and relay module (N10/2) and for vehicles with code (550) Trailer hitch, also to the trailer recognition control unit (N28/1).

The Electronic Stability Program control unit or the regenerative braking system control unit also actuates the rear SAM control unit via a direct line (circuit 54) in order to counteract any delay in the forwarding of the request via the two data buses.

The rear SAM control unit routes this signal over a direct line to the trailer recognition control unit.

The rear SAM control unit receives the request and actuates the following components:

• Left rear lamp unit (E3)
  • Outer left brake light and taillight (E3e11)
• Inner left rear lamp unit (E3/1)
  • Inner left brake light and taillight (E3/1e4)
• Right rear lamp unit (E4)
  • Outer right brake light and taillight (E4e11)
• Inner right rear lamp unit (E4/1)
  • Inner right brake light and taillight (E4/1e4)
• Center brake lamp (E21)

The trailer recognition control unit receives the request and actuates the brake lights of the trailer via the trailer socket (X58).

Additional function requirements, adaptive brake lights 

• Vehicle speed v > 25 km/h
• Brake Assist system active or vehicle deceleration a > 7.5 m/s ²

Function sequence, adaptive brake lights 

In the event of any emergency braking the brake lights and the center brake lamp are actuated and they flash on and off.

The instrument cluster (A1) sends the vehicle speed to the front SAM control unit over the interior CAN.

The Electronic Stability Program control unit or the regenerative braking system control unit transmits the "emergency braking" signal via the chassis CAN, the front SAM control unit and the interior CAN to the rear SAM control unit and in vehicles with code (550) Trailer hitch to the trailer recognition control unit.

The rear SAM control unit actuates the brake lights and the center brake lamp for the duration of the signal at a frequency of f = 3 to 5 Hz and also sends a corresponding signal over the interior CAN to the trailer recognition control unit, which defines the time duration for the dark phase set.

The following frequencies are output, depending on the light sources used on the trailer:

• For bulbs, f = 3 Hz
• For light-emitting diodes, f = 5 Hz

If the vehicle comes to a standstill following emergency braking, the hazard warning flasher function is always automatically activated if braking occurred from a speed of v > 70 km/h.

The danger braking signal is reset if one of the following preconditions is met:

• Vehicle speed v < 10 km/h
• Vehicle deceleration a < 6.5 m/s ²

	Electrical function schematic for brake light actuation		PE82.10-P-2057-97DAA
	Overview of exterior lights system components		GF82.10-P-9998FL