The mirror functions include electric mirror adjustment, mirror heating, mirror memory (option) and electric mirror fold-in (option).
The mirrors are adjusted electrically by means of the peripheral modules for the driver's and passenger's doors. The adjustment switch is located in the central switch block on the driver's door.
Switch operation is transferred via the P-bus from the switch block to the peripheral module in the door. The door module drives the adjustment motors in the mirrors by means of semiconductor bridges.
Electric motors are installed in the mirror housing for horizontal and vertical adjustment.
If the vehicle is equipped with a seat/steering column memory the mirror positions are registered and stored accordingly.
The seat/steering column memory features its own peripheral module (its own diagnosis program) which is linked via the P-bus to the general module of the ZKE. The positions for the seat and steering column are registered and stored in this peripheral module.
Parallel to this, the mirror positions are stored in the peripheral modules of the doors (door modules).
The mirror positions are detected by means of potentiometers which are installed on the mirror drive.
Memory mode is operated by means of the memory switch which is linked by four lines to the peripheral module for the driver's door. Button operation is transferred via the P-bus to the general module.
The mirror, seat and steering column positions are stored as of terminal R. After pressing, the red memory button lights for max. 7 seconds. If one of the memory buttons (1, 2 or 3) is pressed during this time, the current positions are stored in the selected memory slot.
A stored position can be called up at any time. The function is, however, deactivated 16 minutes after switching off the ignition until terminal R is switched on again or until a signal change takes place at a module input (e.g. opening a door).
The positions are called up by pressing the required memory button (1, 2 or 3) until all adjustment have been carried out. In addition, it is possible to start an automatic operating sequence by briefly striking the button. This ”single-strike mode” is possible when:
Mirror heating is controlled by the peripheral modules in the doors. The heating function is active as of terminal 15 (ignition lock position 2). The activation time is dependent on the outside temperature.
The general module receives the outside temperature from the IKE via the K-bus and determines a cycle time for heating operation. This time is transferred to the peripheral modules where it is carried out. Heating is no longer active at an outside temperature greater than 25 oC and it is switched on permanently at a temperature lower than -10 oC.
The electric motor drive is used to fold in the outside mirrors (special option) in the opposite direction of driving.
The button to fold in the mirrors is located in the switch block on the driver's door. The button signal is routed via the P-bus to the peripheral modules in the doors. Depending on the position of the mirrors, they are then folded in or out accordingly.
In addition to the external design differences, the mirrors for the production vehicles model E38/E39 from the mirrors for the model E39 M5 (motorsports design).
A microswitch is integrated in the mirrors the production vehicles that switches a ground signal to the relevant peripheral module when a mirror is folded in or out by hand or by impact. The microswitch is necessary as folding the mirror in or out uncouples the mirror mechanism from the fold-in motor. If a mirror which has been mechanically uncoupled is activated by the button being pressed, the fold-in motor will move the mirror in the fold-in direction until the microswitch registers the mirror being engaged. The maximum activation time of the motor is 15 seconds.
Thanks to a modified mirror mechanism, this microswitch is no longer necessary for the mirror of the E39 M5.
Since the mirror fold-in motors block when operated, thermal overloading is possible if operated frequently. In order to avoid overloading, a repeat lockout is provided which blocks the fold-in motors for 3 minutes after 6 operating attempts within 1 minute.