Brief description of components: Notes

The following components supply signals for the footwell module:

• Ride-height sensors
• Reversing light switch
• Brake light switch
• Hazard warning lights switch
• Light switch
• Driver's door switch block
• Door contacts in rear doors
• Door contacts in front doors
• Driver's door lock

Several control units are involved in the lighting: In a stricter sense, the following control unit are involved in the lighting system (in alphabetical order):

• ACSM/MRS: Crash safety module/multiple-restraint system 
  • E81, E82, E87, E90, E91, E92: Multiple restraint system
  • E70, E71, E93: (ACSM stands for "Advanced Crash Safety Module", also known as the crash safety module)

  The footwell module is connected to the crash safety module/MRS control unit via the K-CAN.

  In the event of an accident with corresponding severity, the footwell module automatically switches on the interior light hazard warning lights.

  • E92

  The crash safety module transmits a message about the status of the front-passenger seat-occupancy detector on the K-CAN.

  The belt feeder on the front-passenger side is only actuated if the front-passenger seat is occupied.

• AHM: Trailer module 

  The trailer module sends a signal indicating whether or not the vehicle is towing a trailer. The trailer module controls the trailer lighting.

  When a trailer is being towed, the trailer module automatically deactivates, for example the rear Park Distance Control (PDC) and the rear foglight on the vehicle.

  The automatic parking function is deactivated whenever a trainer is detected. (Automatic parking function: To improve the view of the curb, the mirror glass is folded downwards when reverse gear is engaged. This brings the area close to the bottom of the vehicle, i.e. the curbside, into view when parking.)

  The trailer module (AHM) is connected to the footwell module via the K-CAN.

• DSC: Dynamic Stability Control 

  When cruise control is in operation, the brake lights are actuated during automatic braking (legal requirement). To this end, a signal must be sent from the DSC to the accelerator pedal module via the PT-CAN.

• FLA: Main-beam assistant 

  In accordance with the traffic situation, the main-beam assistant sends a switch-on recommendation or a switch-off recommendation for the main-beam headlights to the light module or footwell module (FRM). On the basis of this recommendation and various other the input variables, the footwell module decides whether the main-beam headlights should be switched on or off.

• FRM: Footwell module 

  The footwell module is connected to the vehicle with three connectors.

  Two 51-pin connectors connect the main wiring harness. A further 26-pin connector is provided for the connection to the dashboard.

• FZD: Roof control panel 

  The roof control panel is responsible for the interior lighting components in the roof area.

  The basic variant of the roof control panel does not have its own control unit. The front interior lights and the rear interior lights are actuated by the footwell module (FRM).

  The High variant of the roof control panel has its own control unit: the FZD control unit.

  The footwell module is connected to the FZD control unit via the K-CAN.

• JBE: Junction box electronics 

  The luggage compartment lights and the glove compartment lighting are connected to the junction box electronics.

• LDM: Longitudinal dynamics management 

  In conjunction with the LDM, the option "Active Cruise Control" uses the "turn signal" signal from the footwell module to help when changing lanes. In other words, if a left turn signal is given before overtaking, the distance to the vehicle in front is reduced. The vehicle to be overtaken is "ignored" more easily. Conversely, when you move back into the right lane, vehicles being driven there will be monitored more quickly.

• RLS/RLSS: Rain-light sensor/rain-light solar sensor 
  • E81, E82, E87, E90, E91, E92, E93: Rain-light sensor
  • E70, E71: Rain-light solar sensor

  The rain-light sensor measures the ambient brightness outside the vehicle.

  Depending on the ambient lighting conditions, the footwell module will switch the driving lights on or off. To do this, the automatic driving lights control must be activated (light switch in switch position "A").

  • In twilight conditions, the rain-light sensor sends the message "Twilight". The footwell module switches the driving lights on. The automatic headlight-range adjustment for the dipped-beam headlights is actuated.
  • In darkness, the rain-light sensor sends the message "Darkness". The adaptive headlights are then activated when the vehicle is cornering.
• SZL: Steering Column Switch 

  The switch signals from the turn-signal/main-beam switch are picked up and evaluated by the SZL. The evaluated switch signals are resistance-encoded and transmitted from the SZL by direct wires to the footwell module.

The following components are controlled:

• Exterior mirrors
• Power window drive
• Headlights
• Rear lights
• Front foglights
• Additional brake light
• Auxiliary turn signal light
• Courtesy lighting, front
• Courtesy lighting, rear
• Licence-plate light
• 2 stepper motor controllers for the adaptive headlight stepper motors
• 2 belt feeder controllers (E92 only)