System Activation And Calibration Sequence
When terminal 15 is switched ON, the headlights always perform a calibration sequence, even if the lights are not switched on. The AHL control unit sends the "perform calibration sequence" request to the stepper motor controllers (SMCs, control units for the headlight stepper motors). The stepper motor controllers actuate the stepper motors in the headlights. The calibration sequence is performed. During the calibration sequence, the headlights move in the following manner
- The headlights move horizontally (= calibration sequence for the AHL).
- The headlights move vertically (= calibration sequence for the headlight-range adjustment function).
- At the end of the calibration sequence, the headlights are in the straight-ahead position.
Following the calibration sequence, the system is ready for operation.
When reverse gear is engaged, the headlights are moved to the straight-ahead position.
Note. The calibration sequence is performed only after terminal 15 has been switched OFF for at least 15 seconds.
If terminal 15 is switched on and off repeatedly (for example, for demonstration reasons), the headlights are not calibrated each time terminal 15 is switched on.
Terminal 15 must have been switched off for at least 15 seconds before it is switched on again. Only then is a calibration sequence performed when terminal 15 is switched on.
Activation Of Automatic Headlight-Range Adjustment By The AHL Control Unit
If special equipment "Adaptive headlights" is fitted, the AHL control unit also controls the automatic headlight-range adjustment.
The automatic headlight-range adjustment adapts the headlight range for different operating conditions. Variations in the vehicle tilt angle are produced by vehicle loads and braking or acceleration in extreme driving situations. The automatic headlight-range adjustment tilts the headlights up and down as required.
The AHL control unit controls the automatic headlight-range adjustment as follows
- The ride-height sensors and the brake light switch send the input signals for the headlight-range adjustment to the AHL control unit.
- From the input signals received, the AHL control unit calculates the vehicle tilt angle (along the longitudinal axis, relative to the road surface).
- Using the stepper motors for moving the headlights vertically, the headlight range is adjusted automatically and dynamically.
The headlight range is adjusted so that the actual headlight range conforms to the legally required headlight range as follows
- If vehicle rear is lower than front - The actual headlight range will be longer than the legally stipulated range. The headlight beam height is lowered to reduce the headlight range to match the legal requirement.
- If the vehicle is horizontal - The actual headlight range will be the same as the legally stipulated range.
- If vehicle front is lower than rear - The actual headlight range will be shorter than the legally stipulated range. The headlight beam height is raised to increase the headlight range to match the legal requirement.
The seat adjustment buttons are located on the outer sides of the seat cushions. They vary in terms of number and function. The E64 seat is additionally equipped with an option for electrically adjusting the head restraints (headrests).
Seat Adjustment Drive Units
The following drive units are installed in the E63 and E64 seat
- Drive unit for seat forward/backward adjustment with 2 adjustment speeds
- Drive unit for seat height adjustment
- Drive unit for seat cushion tilt adjustment
- Drive unit for backrest angle adjustment
Additionally installed in the E64
- Drive unit for head restraint height adjustment
Head Restraint Angle Adjustment
The head restraint angle adjustment as well as the seat depth adjustment on the sports seat are always manual.
Seat Adjustment
The installed seats feature the following seat adjustment options
- Seat forward/backward adjustment (with electric drive unit, 2 speed stages)
- Seat height adjustment (with electric drive unit)
- Seat depth adjustment (manual only, sports seat only)
- Backrest angle adjustment (with electric drive unit)
- Head restraint height adjustment (E63: manual; E64: with electric drive unit)
- Head restraint angle adjustment (manual only)
- Lumbar support height adjustment (electro-pneumatic)
- Lumbar support depth adjustment (electro-pneumatic)
The standard seat forward/backward adjustment, seat height adjustment, seat cushion tilt adjustment and backrest angle adjustment facilities are each operated with separate electric drive units in all seats. The head restraint height adjustment is driven by an electric drive unit only on the E64.
All these functions are controlled via the control panel on the outer sides of the seat cushions. Signals from the respective button trigger seat adjustment in the required directions.
A separate rocker switch is used to operate the lumbar support. An electric pump supplies the lumbar support cushion with compressed air. The individual air chambers are filled or emptied via several valves to vary the height and thickness of the lumbar support.
The limit stop is calculated for each drive unit in order to reduce the load of the electric drive units to a minimum. Automatic recognition of the limit stops is integrated in each of the electric drive units. Hall sensors integrated in the drive units register the adjustment distances which are processed in the seat module. In the event of the drive unit blocking, the detected position value is interpreted as the limit stop. All subsequent adjustments are interrupted just before this point.
Once the obstruction has been removed, adjustment can again extend beyond the newly detected limit stop when the seat adjustment button is pressed again.
Steering Column Adjustment
The fully electric steering-column adjustment allows the driver to set the steering wheel to the best possible position. This is done with a switch on the left-hand side of the steering column. The tilt and fore-and-aft position of the steering column are adjusted by means of an electric motor.
Scheme 445
Vehicles with electric steering column adjustment have a steering-column memory in conjunction with seat memory and mirror memory.
The steering-column adjustment is actuated by the SZM. One motor drives the tilt and fore-and-aft adjustment. A second motor changes the direction of adjustment via the adjustment gears.
Possible functions of steering column adjustment are
- Height adjustment
- Reach adjustment
- Entry/exit aid
- Steering-column memory
- Motor protection
Scheme 446
Switch For Steering-Column Adjustment
This switch enables the driver to adjust the tilt and fore-and-aft setting of the steering column. The switch for steering-column adjustment is on the left-hand side of the steering column.
Steering-Column Adjustment Drive Unit
Two motors are built into the drive unit. 1 motor drives the tilt and fore-and-aft adjustment of the steering column. The second motor changes the direction of adjustment via the adjustment gears.
The adjustment movement and position recognition for both tilt and fore-and-aft adjustment are recorded in the drive unit for the steering-column memory. There are 2 Hall sensors and 2 magnetic rings (16-pin) integrated in the drive unit.
Manual Steering-Column Adjustment
The driver is able to adjust the steering column with a switch. When the switch is operated, the signal is transmitted cyclically from terminal 30 (cycle time: 100 milliseconds). The steering-column adjustment is actuated for as long as the signal is being received.
Once the switch is no longer actuated, the message "Stop" is transmitted 3 times.
The steering-column adjustment is stopped when this signal is received, or if the cyclic message is not received twice.
To enable a failure of the steering column switch cluster to be detected, a further a cyclic message is transmitted when the data bus is active (cycle time: 1 second).
When changing the direction of adjustment, the center console switch cluster first actuates the motor for setting the adjustment gears.
The actuation of this motor is time-dependent. The adjustment motor is not actuated until the direction of adjustment is correctly set. The total adjustment movement is no more than 36 millimeters for tilt adjustment and 40 millimeters for fore-and-aft adjustment.
Steering-Column Memory
The position of the steering column in each direction of adjustment is recorded by a Hall sensor. This position is stored in the center console switch cluster (SZM). This allows the Key Memory to call up the position of the steering column for up to 4 vehicle keys.
The tilt adjustment moves to the uppermost position to make it easier to get in and out of the vehicle.
For the easy-access facility, the steering-column adjustment is automatically actuated under the following conditions
- Terminal R OFF
- Terminal R ON and driver's door opened (via door contact)
- Terminal 15 OFF with driver's door open (via door contact)
The steering-column memory is activated under the following conditions
- One of the two memory buttons for the seat-mirror memory and the steering-column memory on the seat is pressed (from terminal R OFF).
- Another remote control is used (personalization). Condition: The selection "Last seat position after unlocking" is activated in the "Settings" menu in the Central Information Display (CID) (from 09/2003).
In both cases, the steering-column memory will not move the steering column to the stored position until terminal 15 is switched ON.
Overheating Protection For Steering-Column Adjustment Motors
To protect the motors against overheating, a temperature model is stored in the center console switch cluster.
The temperature model makes allowance for the warming up and cooling down of the motors.
It is possible to move the steering column in either direction through the range of movement at least 6 times before overheating protection is activated.