Brake Light Actuation, Function - GF82.10-P-3010RDM
Model 172.4 as of model year 2017
Function requirements, brake light actuation, general
- No overvoltage or undervoltage (operating voltage range U ≥ 7 ≤ 17.5 V)
- Terminal 15 ON
The electronic ignition switch control unit (N73) sends the status of circuit 15 to the front SAM control unit with fuse and relay module (N10/1) via 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 lights switch (S9/1) is powered by the Electronic Stability Program control unit (N30/4) over circuit 15.
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 1 (CAN E1), 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):
- Upper left brake light (E3e23)
- Lower left brake light (E3e24)
- Right rear lamp unit (E4):
- Upper right brake light (E4e23)
- Lower right brake light (E4e24)
- 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 over the chassis CAN 1, front SAM control unit and the 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 Electronic Stability Program control unit sends the "Emergency braking" signal over the chassis CAN 1, front SAM control unit and the 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 left rear fog light or the right rear fog light is actuated during the active brake light actuation (depending on the country coding), the lower left brake light or the lower right brake light is deactivated.
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 CAN signal "Emergency braking" 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-2057-97TAB | ||
| Overview of exterior lights system components | GF82.10-P-9998RDM |