Hazard Warning Lamps: Description and Operation

GF82.10-P-3080RC Substitute Lights And Emergency Lights Actuation, Function

Function requirements backup/emergency lights actuation in general
^ Circuit 15 On

Backup/emergency lights actuation, general
The backup/emergency lights actuation ensures the minimum exterior lighting if the event of failure of individual system components of vehicle exterior illumination.

The backup/emergency lights actuation is comprised of the following subfunctions:
^ Function sequence for substitute lamp actuation
^ Function sequence, emergency lights actuation

Function sequence for substitute lamp actuation
The function of all the lamps in the vehicle's exterior lights are checked. If certain lamps fail, their function is reproduced through actuation of other lamps with pulse width modulation where applicable. In such an instance, flashing functions have priority over steady light.

An active automatic lamp substitution function is communicated to the instrument cluster (A1) from the driver SAM control unit with fuse and relay module (N10/1) or from the rear SAM control unit with fuse and relay module (N10/2) via the interior CAN. The instrument cluster (A1) shows the "Substitute lights active" message.
The scope of the substitute lamp actuation is country-specific.







Function sequence, emergency lights actuation
The objective of the emergency lights actuation is to avoid any complete failure of the vehicle's exterior lights in the event of a processor failure or through failure of the interior CAN. To this end, both the driver SAM control unit and the rear SAM control unit have separate hardware, which guarantees the emergency light function.

In the event of a failure of the interior CAN or an SAM control unit, the front standing lights and low beams actuation are activated within a period t < 3 s from the separate hardware in the driver SAM control unit and the standing lights actuation is also activated and - depending on terminal status circuit 54 - the brake light actuation by the separate hardware in the rear SAM control unit.