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

Model 172.4 up to model year 2017 

Function requirements, general 

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

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

Brake light actuation, general 

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

Brake light actuation function sequence 

The brake light switch (S9/1) is supplied with voltage by the Electronic Stability Program control unit (N30/4). When the service brake is operated, the brake lights switch switches the applied voltage through to the Electronic Stability Program control unit. The Electronic Stability Program control unit sends the status of the service brake via chassis CAN (CAN E), front SAM control unit and interior CAN to the rear SAM control unit with fuse and relay module (N10/2). In addition, the Electronic Stability Program control unit actuates the rear SAM control unit via a direct line (circuit 54) in order to counteract any delay in the forwarding of the request over the two data buses.

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

• Left rear lamp unit (E3):
  • Left brake light (E3e4)
  • Inner left brake light and taillight (E3e10)
  • Outer left brake light and taillight (E3e11)
• Right rear lamp unit (E4):
  • Right brake light (E4e4)
  • Inner right brake light and taillight (E4e10)
  • Outer right brake light and taillight (E4e11)
• Center brake lamp (E21)

The brake lights and center brake lamp are also actuated if the electric parking brake switch (S76/15) is pressed while driving. The electric parking brake control unit (N128) directly reads in the status of the electric parking brake switch and sends the "Brake light ON" request via chassis CAN, front SAM control unit and interior CAN to the rear SAM control unit.

If, at a vehicle speed of v > 25 km/h, emergency braking (BAS active or vehicle deceleration a > 7, 5 m/s² ) is initiated, then the brake lights and the center brake lamp are actuated to flash on and off. The instrument cluster (A1) sends the vehicle speed to the front SAM control unit over the interior CAN. The ESP® control unit sends the "Emergency braking" signal via chassis CAN, front SAM control unit and interior CAN to the rear SAM control unit. The rear SAM control unit actuates the brake lights and the center brake lamp with a frequency of f = 3 to 5 Hz for the duration of the signal.

If the rear fog lamp actuation is switched on during the active brake light actuation, the inner left brake light and taillight or the inner right brake light and taillight (depending on the country coding) is actuated with reduced output.

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

The "Emergency braking" CAN 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-2057-97TAA
	Overview of exterior lights system components		GF82.10-P-9998RD