Brake Light Actuation, Function - GF82.10-P-3010RF

Model 205, Model 253 

Function requirements, general 

• No overvoltage or undervoltage
• Circuit 15 ON or "Standstill" signal not set

The electronic ignition lock control unit (N73) sends the status of terminal 15 to the rear SAM control unit (N10/8) via the interior CAN (CAN B).

The front SAM control unit (N10/6) also actuates the rear SAM control unit via a direct line (circuit 15) in order to counteract any delayed forwarding of the request via the CAN buses.

The Electronic Stability Program control unit (N30/4) transmits the "Standstill" signal to the rear SAM control unit via the suspension FlexRay (Flex E), electronic ignition lock control unit and interior CAN.

Brake light actuation, general 

The brake light actuation design can be adapted. In the event of emergency braking, the vehicle brake lights are actuated to flash on and off.

Brake light actuation function sequence 

When the service brake is operated, the brake light switch (S9/1) (except hybrid vehicles and except model 253.99) or the pedal angle sensor (B37/1) (hybrid vehicles and model 253.99) is actuated. The Electronic Stability Program control unit directly reads in the status of the brake light switch or the signal of the pedal angle sensor and transmits the status of the service brake to the rear SAM control unit and also to the trailer recognition control unit (N28/1) in vehicles with code 550 (Trailer hitch) via the suspension FlexRay, electronic ignition lock control unit and interior CAN.

The Electronic Stability Program control unit also actuates the rear SAM control unit via a direct line (circuit 54) in order to counteract any delayed forwarding of the request via the CAN buses. The rear SAM control unit routes this signal via a direct line to the trailer recognition control unit.

In the event of a defective brake light switch or a defective pedal angle sensor, any braking is registered by the Electronic Stability Program control unit by way of the brake pressure.

The rear SAM control unit receives the status of the service brake and actuates the following components:

• Left rear lamp unit (E3):
  • Left brake light (E3e4) (except model 205.0/1 as of 01.06.2018 with LED headlamp)
  • Outer left brake light and taillight (E3e11) (Model 205.3/4)
  • Left tail light (E3e18) (Model 205.0/1 up to 31.05.2018 with LED headlamp, Model 205.2, Model 253.9)
  • Upper left brake light (E3e23) (Model 205.0/1 as of 01.06.2018, with LED headlamp)
  • Outer lower left brake light (E3e30) (Model 205.0/1 as of 01.06.2018, with LED headlamp)
  • Inner lower left brake light (E3e31) (Model 205.0/1 as of 01.06.2018, with LED headlamp)
• Right rear lamp unit (E4):
  • Right brake light (E4e4) (except model 205.0/1 as of 01.06.2018 with LED headlamp)
  • Outer right brake light and taillight (E4e11) (Model 205.3/4)
  • Right tail light (E4e18) (Model 205.0/1 up to 31.05.2018 with LED headlamp, Model 205.2, Model 253.9)
  • Upper right brake light (E4e23) (Model 205.0/1 as of 01.06.2018, with LED headlamp)
  • Outer lower right brake light (E4e30) (Model 205.0/1 as of 01.06.2018, with LED headlamp)
  • Inner lower right brake light (E4e31) (Model 205.0/1 as of 01.06.2018, with LED headlamp)
• Center brake lamp (E21)

Model 253.9 (except 253.99)

as of model year 2020

with code 460 (Canada version)

Model 253.9 (except 253.99)

as of model year 2020

with code 494 (US version)

The left or right brake light is overriden by flashing. This means that in the dark phase of flashing, the brake light in question is switched off despite a braking procedure.

In vehicles with code (550) Trailer hitch, the trailer recognition control unit receives the incoming information and actuates the brake lights of the trailer via the trailer socket (X58).

The brake lights and center brake lamp are actuated if the electric parking brake switch (S76/15) is pressed while driving.

Vehicles without engine 177 up to 31.05.2018 or vehicles as of 01.06.2018 

The Electronic Stability Program control unit reads in the status of the electric parking brake switch directly and sends the "Brake lights ON" request over the chassis FlexRay, electronic ignition lock control unit and interior CAN to the rear SAM control unit and on vehicles with CODE (550 (Trailer hitch), also to the trailer recognition control unit.

Vehicles with engine 177 up to 31.05.2018 

The electric parking brake control unit (N128) reads in the status of the electric parking brake switch directly, and sends the "Brake light ON" request over the periphery CAN (CAN PER), electronic ignition lock control unit and the interior CAN to the rear SAM control unit, and on vehicles with CODE 550 (Trailer hitch), also to the trailer recognition control unit.

If, at a vehicle speed of v > 50 km/h emergency braking is initiated (Active Brake Assist or vehicle deceleration a > 7.5 m/s² ), the brake lights and center high-mounted brake lamp flashing is actuated.

The instrument cluster (A1) sends the vehicle speed over the user interface CAN (CAN HMI), electronic ignition lock control unit and the interior CAN to the rear SAM control unit.

The Electronic Stability Program control unit sends the "Emergency braking" signal via the chassis FlexRay, electronic ignition lock control unit, and interior CAN to the rear SAM control unit and additionally 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 high-mounted brake lamp at a frequency of f = 3 to 5 Hz for the duration of the signal. In vehicles with code (550) Trailer hitch, the rear SAM control unit sends a corresponding signal that defines the period for which the dark phase is set, over the interior CAN to the trailer recognition control unit.

The trailer recognition control unit then actuates the trailer brake lights through the trailer socket.

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 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/s²

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