Brief Description Of Components

The following components are required for Comfort Access:

• Interior and exterior aerials 

  A total of 12 aerials are required for communication with the ID transmitter:

  • 6 interior aerials: Driver's footwell and front-passenger footwell, rear-compartment footwell left and right, rear window shelf, luggage compartment
  • 6 exterior aerials: outside door handle on all 4 doors, double aerial in rear bumper

  The aerials emit 125 kHz radio signals which are evaluated by the ID transmitter.

• Outside door handle electronics 

  There is electronic circuitry in the outside door handle on all 4 doors.

  The 3 sensors in the outside door handle electronics send the following signals to the CAS and CA control units:

  • Start check: When a hand reaches into the handle recess via a capacitive sensor
  • Unlock: When the outside door handle is pulled via a pull sensor
  • Locking and deadlocking: When the outside door handle pressed via press sensor

  A built-in aerial also sends radio signals in order to check for an ID transmitter located on the outside of the driver's door or front-passenger door.

• ID transmitter 

  The ID transmitter evaluates the signals from the aerials. It also sends high-frequency radio signals to the FBD receiver.

  Inserting the ID transmitter into the insert compartment deactivates all Comfort Access functions.

• Remote control receiver 

  The remote control receiver (FBD receiver) is located in the right-hand C-pillar. The FBD receiver receives the radio signals from the ID transmitter and forwards them to the CAS control unit. The Comfort Access (CA) control unit activates the FBD receiver.

• Electric motor on door lock 

  Each of the 4 door locks also has an additional electric motor. The electric motor provides early release of the locking pawl in the door lock.

• Tailgate button 

  The tailgate button supplies a signal to the power module (PM) when the tailgate is opened. The power module sends the signal to the CAS control unit.

• START/STOP button 

  The START/STOP button can be used to switch the terminals in sequence (0, R, 15, R, 0). When the brake is depressed (automatic transmission) and the START/STOP button is pressed, the engine will start.

• Insert compartment for the ID transmitter/remote control 

  The remote control must be inserted into the insert compartment if the battery in the ID transmitter is discharged. The engine can then be started up.

  Inserting the ID transmitter into the insert compartment deactivates Comfort Access.

Various control units are involved in the system:

• CAS: Car Access System 

  The CAS control unit is the master control unit for all Comfort Access functions. The CAS control unit is the interface to the START/STOP button and to the insert compartment for the ID transmitter.

  The CAS control unit is connected with the following components via the K-bus (sub-bus):

  • Electronic circuitry in the outside door handles of all 4 doors
  • Comfort Access (CA) control unit

  When the vehicle is idle, communication may take place on the K-bus without waking up the vehicle.

  At the same time, the CAS also communicates with the CA control unit on the K-CAN PERIPHERY.

  The sub-bus is activated when a signal is triggered from an outside door handle. If identification is negative, the sub-bus goes back into standby mode.

• TMFA, TMBF, TMFAH, TMBFH: 4 door modules 

  The door modules control the central locking. If the CAS control unit approves the unlocking of the vehicle, for example, the doors will be unlocked.

  The Comfort Access sub-bus is simply looped through the door modules.

  The "door handle pulled" signal is transmitted by the door module to the CAS control unit via the K-CAN PERIPHERY.

• CA: Comfort Access control unit 

  The Comfort Access (CA) control unit actuates the interior aerials and the two exterior aerials in the rear bumper.

  An ID transmitter scan is carried out. At the same time, the FBD receiver is activated for any ID transmitters which may respond.

• PM: Power module 

  The tailgate button for opening the tailgate is connected to the power module. The signal is sent to the CAS control unit via the K-CAN PERIPHERY.

  This means that the tailgate can also be opened individually.

The Active Cruise Control option consists of the following components:

• ACC sensor with control unit 

  The ACC sensor and control unit form a single unit.

  The ACC sensor monitors the distance, angle and relative speed of vehicles driving ahead. (Relative speed: The relative speed is the difference in speed between the two moving objects, i.e. relative to each other.)

  The ACC sensor is a radar sensor. The ACC sensor has a limited monitoring range (approximately 120 meters).

• Cruise-control system steering-column stalk 

  Cruise control is set and called up using the Active Cruise Control system steering-column stalk.

• 2 brake pressure sensors 

  A brake pressure sensor is installed in each of the front and rear axle brake circuits. The signals from the brake pressure sensors are evaluated by the Dynamic Stability Control.

  If Active Cruise Control is in use, the vehicle will be braked as necessary by the Dynamic Stability Control (DSC) (not DSC intervention). The brake pressure sensors all the brake pressure, which is often only very slight, to be regulated to the front and rear axles

  • Vehicles with DSC 8Plus:

    The brake pressure sensors have been discontinued on vehicles with DSC 8Plus. DSC 8Plus is an advanced development of the familiar DSC 8.

In addition, the ACC control unit communicates with the following control units:

• DME or DDE: Digital engine electronics or digital diesel electronics 

  The DME/DDE controls the engine intervention. The following data is transmitted by the ACC sensor to the DME or DDE:

  • Current torque request

  The following data are transmitted from the DME or DDE to the ACC sensor:

  • Driver's command (signals from accelerator pedal module)
• SGM: Safety and gateway module 

  > E65, E66 as well as

  E60, E61, E63, E64 up to 09/2005:

  The SGM is the gateway (= data interface) between:

  • PT CAN
  • K-CAN
  • Byteflight 

  The diagnosis lead is also connected at the SGM.

  > E60, E61, E63, E64 from 09/2005

  The body-gateway module replaces the safety and gateway module (SGM).

• KGM: Body-gateway module 

  > E60, E61, E63, E64 from 09/2005

  The KGM is the gateway (= data interface) between:

  • PT CAN
  • K-CAN

  The diagnosis lead is also connected at the KGM.

• DSC: Dynamic Stability Control 

  The current status of the vehicle is detected by the DSC, for example by evaluating the following sensor signals:

  • Rate of yaw (measure of movement of the car about its vertical axis)
  • Steering angle
  • Information on the brake pressure
  • Circumferential wheel speed

  DSC then transmits data about current operating conditions to the ACC sensor.

  The following data are transmitted by the ACC sensor to the DSC:

  • Request for vehicle deceleration:

  DSC receives the request for vehicle deceleration from the Active Cruise Control via the PT-CAN. DSC reduces the speed. To do this, DSC intervenes in the brake system. (goal: comfortable vehicle deceleration. No DSC intervention in the sense of enhanced operating stability.)

  With automatic braking, the brake lights are actuated depending on the vehicle deceleration and the gradient of the road (legally prescribed).

• FPM: Accelerator pedal module 

  The accelerator pedal module signals the driver's command. This signal is required to check the respective driving status. (evaluation via DME/DDE)

  By pressing the accelerator pedal, the speed setpoint of the Active Cruise Control can be overridden at any time.

• Brake light switch 

  The brake light switch tells the active cruise control when the brake pedal has been pressed. Active Cruise Control is deactivated if braking actions are necessary.

• Clutch mode  (manual transmission only)

Clutch engagement/disengagement is recognized by the signal from the clutch module.

During the clutch engagement/disengagement process, the engine speed is maintained at an optimal speed range by the DME or DDE.

After the clutch has been reengaged, the DME/DDE will adjust back to the current torque request from the Active Cruise Control.

If the engine speed is too high or too low, an audible signal and a check control message prompt the driver to change gear. The prompt to upshift when the engine speed is too high is only made during the warm-up phase of the engine.

If no gearshift or change in engine speed is made within approx. 5 seconds of such a signal being given, active cruise control will be deactivated.

If the clutch is disengaged for longer than about 6 seconds, Active Cruise Control (ACC) will be deactivated.

Active cruise control cannot be activated in 1st gear.

Active cruise control is automatically deactivated in the "neutral gate" (i.e. no gear engaged and clutch not depressed).

Only install prescribed rear differential unit. 

Active Cruise Control has a variant coding which is co-ordinated with the differential ratio. If a different rear differential unit is installed, it may be the case that the Active Cruise Control will deactivate itself in manual transmissions, particularly in the higher gears. In this case, no fault is entered in the fault memory.

• EGS and SMG: electronic transmission control and sequential manual transmission 
  • Electronic transmission control

    The electronic transmission control evaluates the data from the DME/DDE and ACC sensor.

    The adaptive transmission control (constituent component of electronic transmission control) adapts the shift characteristics of the driving programed to the driver's commands and the driving situation.

  • Sequential manual gearbox

    No automatic upshift in manual mode.

    In order to prevent excessively high engine speeds, an audible signal and check control message prompt the driver to change gear. The prompt to upshift when the engine speed is too high is only made during the warm-up phase of the engine.

  The following data are transmitted from the EGS or SMG to the ACC sensor:

  • Gear engaged
  • status information about gearshifts

  The ACC sensor transmits the following data to the EGS/SMG:

  • Current operating status
  • Current torque request
• LM: Light module 

  When active cruise control is in operation, the brake lights are actuated during automatic braking (legal requirement). This requires a signal sent via the K-CAN to the light module.

  Active cruise control uses the "turn signals" signal from the light module for assistance 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.

• SZL: Steering column switch cluster 

  The SZL processes all data from the cruise-control system steering-column stalk.

  > E65, E66 as well as

  E60, E61, E63, E64 before 09/2005

  The SZL is connected to the safety and gateway module (SGM) via the byteflight  . The SGM creates the connection to the bus system.

  > E60, E61, E63, E64 from 09/2005

  The SZL is connected to the bus system via the PT-CAN.

• Displays in the instrument cluster 

  For Active Cruise Control, the following displays are available in the instrument cluster:

  • Set speed via an indicator disc

    (Set speed = selected km/h of the cruise control system)

  • Monitored vehicle

    (Display through lit up icon)

  • Request for action to driver

    (Display through flashing icon. In addition, an audible warning is made.)

  • Selected distance from vehicle driving ahead

    (Display via icon)

  • The LC display briefly shows the newly selected set speed (approximately 6 seconds).
  • Check control message in LC display
• M-ASK or CCC and CID:Multi-audio system controller/Car Communication Computer and Central Information Display 

  > E60, E61, E63, E64 only

  For the instrument cluster, the M-ASK and CCC serve as an interface to the Central Information Display (CID).

  Amongst other things, the CID displays detailed information about the check control messages. To back up the check control message, the M-ASK/CCC emit acoustic warnings through the loudspeakers (depending on national version). The instrument cluster assumes control over these warnings via the K-CAN.

  • CCC with Professional navigation system option 609:

  Only in the combination of CCC with Professional navigation system option 609 are the additional scopes of operation possible for the dynamics control behavior.

• CD: Control display 

  > E65, E66 only

  The control display is the central display for the information and communication system.

  The control display is used as an interface between the MOST and K-CAN data buses. (MOST stands for "Media Oriented System Transport"; K-CAN stands for "Body Controller Area Network".)

  Amongst other things, the control display displays detailed information about the check control messages. The instrument cluster controls these warnings by means of the K-CAN.

• CAS: Car Access System 

  The CAS provides input signals relating to terminal status (e.g. terminal 15 ON).

• HUD: Head-up display 

  > E60, E61, E63, E64 only

  The Head-up display (option 610) displays the following information:

  • Set speed
  • Object ahead monitored
  • Request for action to driver
  • Timed separation setting
  • Check-control messages