Hazard Warning Lamps: Description and Operation
GF82.10-P-3080GM Substitute Lights And Emergency Lights Actuation, Function
Function requirements, substitute/emergency lights actuation, general
^ Circuit 15 On
The circuit status of circuit 15 is provided by the EIS [EZS] control unit (N73) on the interior CAN (CAN-B).
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 vehicle exterior lighting bulbs is checked. If certain bulbs fail, their function is simulated by actuating other bulbs, with pulse width modulation if necessary.
In such an instance, flashing functions have priority over steady light.
The scope of the substitute lamp actuation depends on the national version and is coded in the central gateway control unit (N93).
A distinction is made between the following variants of the substitute lamp actuation:
- Minimum variant (limited substitute lights)
- Maximum variant (complete substitute lights)
The minimum variant (restricted substitute lights) is used in the following countries:
- Vehicles with code (460) Canada version
- Vehicles with code (494) USA version
- Vehicles with code (498) Japan version
- Vehicles with code (625) Australia version
- China vehicles
The left turn signal light (E1e5) and the right turn signal light (E2e5) must not be replaced with pulsed front fog lamp actuation (model 164.1, model 251.0/1, model 164.8 up to 30.6.09 and as of 1.7.09 with code (498) Japan version or without code (615) Bi-xenon headlamp unit with integral curve illumination and without code (616) Bi-xenon headlamp unit with integral asymmetrical curve illumination and without (621) Intelligent Light System (left-hand traffic) and without code (622) Intelligent Light System (right-hand traffic)).
In vehicles with code (460) Canada version or code (494) USA version, the left turn signal light (E3e1) and right turn signal light (E4e1) may only be replaced if the vehicle is equipped with the turn signaling function. This is implemented via separate variant coding in the rear SAM control unit (N10/8).
The instrument cluster (A1) is notified that the automatic lamp substitution function is active by the front SAM control unit (N10) and the rear SAM control unit via the interior CAN.
The message "substitute lights active" is displayed on the multifunction display of the instrument cluster (A1p13).
Function sequence, emergency lights actuation
The aim of the emergency lights actuation is to prevent a complete failure of the vehicle outside lights due to a processor failure or due to the failure of the interior CAN. To this end, both the front 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 light and low beam actuation are activated within a period of t < 1 s by the independent hardware in the front SAM control unit and the standing lights actuation and (depending on terminal status circuit 54) the brake light actuation are also activated by the independent hardware in the rear SAM control unit.
