Brake Lamp: Description and Operation

GF82.10-P-3010TY Stop Lamp Actuation, Function

Component Identification:

Stop lamp actuation
Function requirements
^ Circuit 15 ON

Function
When the service brake is actuated, voltage is applied over the switching contacts in the stop lamp switch to the ESP control unit, which then sends the "Stop lamp on" signal via CAN-C to the central gateway control unit. The central gateway control unit relays the "Stop lamp on" signal via CAN-B to the rear SAM control unit.
At the same time, the ESP control unit forwards the "Stop lamp On" signal (circuit 54) directly to the rear SAM control unit. The rear SAM control unit actuates the stop lamps and the center high-mounted stop lamp.

This direct actuation should prevent any time delay in forwarding the switch-on request actuated by the stop lamp switch over the two CAN data buses.

Along with its actual task of actuating the stop lamps, the stop lamp signal is also important for other functional areas in the vehicle, and for this reason it is sent from the central gateway control unit to CAN-B and CAN-C.

The stop lamps and the center high-mounted stop lamp are designed as a light emitting diode (LED) light source.

Stop lamp actuation, flashing on and off (emergency braking signal)

Function requirements
^ Brake actuated
^ Vehicle speed > 50 km/h
^ Brake Assist System active or vehicle deceleration > 7.5 m/s2

Function
In the event of an emergency stop, the ESP control unit generates a corresponding signal on CAN-C.
The central gateway control unit forwards this over CAN-B to the rear SAM control unit. The rear SAM control unit then actuates the stop lamps and the center high-mounted stop lamp with a flashing frequency of 5 Hz for the duration of the signal (min. 1 s).

After the vehicle has come to a standstill, the stop lamps and the center high-mounted stop lamp are continuously actuated again. The automatic hazard warning flasher function is also activated.

The emergency stop signal is reset, when one of the following conditions is complied with:
- Brake not actuated
- vehicle speed < 10 km/h
- Brake Assist System inactive and vehicle deceleration < 6.5 m/s2 for min. 150 ms

The stop lamp flashing on and off function is used for all vehicles with EC model homologation.