The photodiode emits an infrared light beam of known intensity; the emitted light exits through the lens and is reflected by the windshield.
The reflected light beam enters back through the lens and then reaches the photodiode. The corresponding value taken without moisture on the windshield is used as the reference value for the automatic calibration process.
Subsequent deviations from this value cause the windshield wipers to be switched on.
If rain lands on the windshield then the light reflected by the windshield has a lower intensity. This loss of intensity is registered by the photodiode and, proportionally to the loss of intensity, the module switches on the windshield wipers with the required wipe speed (in intermittent or continuous mode).
When the automatic wipe function is switched on (wiper lever to intermittent position) the wipers are only activated automatically if the rain sensor registers water on the windshield.
It is not necessary to calibrate the rain sensor, as this has already been done at the factory.
The sensitivity of the rain sensor can be changed by adjusting the control resistor for the intermittent mode of the windshield wipers.
- Adjusting ring position - wide symbol: High sensitivity
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The wipers wipe even if only a small amount of water has been measured on the windshield.
- Adjusting ring position - narrow symbol: Low sensitivity
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The wipers only wipe if a large amount of water has been measured on the windshield.
Rear window wash/wipe system
The rear window wash/wipe system will only operate if the ignition switch is in the position "II".
If the windshield wiper switch is in the "Off", "Intermittent mode" or "Automatic wipe" (no wiping or low speed) position, then the wipe interval of the rear window wiper is 10 seconds.
If, on a vehicle equipped with a rain sensor, the windshield wiper switch is set to intermittent mode, speed 1 or speed 2 and rain is detected on the windshield then the rear wiper will come on in intermittent mode with a delay of 10 seconds between wipes.
If the switch for the rear window washer is pressed, then washer fluid is sprayed onto the rear window, and the wiper operates continuously at low speed. When the switch is released the rear window wiper performs another 2-3 wipes.
If reverse gear is engaged and the windshield wiper switch is in the normal, high speed or automatic windshield wiper (wiping at high speed) position, the rear window wiper will operate continuously until the gearshift lever is moved back to the neutral position.
If reverse gear is engaged and a single wipe of the windshield wiper is performed via the one-touch function then the rear wiper also performs a single wipe.
Headlamp washer system
The headlamp washer system will start to operate when the windshield washer function is activated if, at the same time, the light switch is set to "dipped beam" or the headlamps have been switched on by the "automatic headlamps" function. Electrical control is performed by the headlamp washer system relay which itself is controlled by the generic electronic module (GEM).
In order to prevent excessive water consumption, the headlamp washer system is only activated every fourth time the windshield wash/wipe switch is operated, provided the time elapsed since the first operation of the headlamp washer system does not exceed 10 minutes. If the windshield wash/wipe switch is activated again after 10 minutes the headlamp washer system is activated and the time encoder is restarted.
If the wash water level warning lamp on the instrument cluster comes on because the wash water level in the washer reservoir is too low then the headlamp washer pump is no longer activated until the washer reservoir is topped up.
central door locking
Locking/unlocking – central locking
The central locking system locks all doors and the liftgate, so that none of these can be opened from the outside of the vehicle.
On vehicles with door modules in the front and rear doors, all door lock motors and door lock switches are controlled via the door locking modules. The signals from the door contact switches are forwarded directly to the GEM.
On vehicles without rear door modules the door lock motors are also directly actuated by the GEM.
Vehicles without rear door modules only have manually operated windows in the rear.
Vehicles with 4 door modules can be identified by the two-stage window regulator switches in the front and rear.
If one of the doors is not properly closed when the central locking function is performed then all doors are locked and unlocked again. This procedure is signaled acoustically.
The turn signal lamps flash twice when the vehicle has been successfully centrally locked.
Locking/unlocking – double locking
The double locking system locks all doors so that they cannot be opened from outside the vehicle. In addition to the central locking function, the double locking system also disconnects the door opening levers from the locking mechanism. This means that the doors can no longer be opened from inside the vehicle.
The double locking mechanism only works when the ignition key is not in the ignition lock.
If the ignition key has been turned to position "I" then the vehicle is centrally locked but not double-locked.
If on a double-locked vehicle the corresponding ignition key is inserted into the ignition, the system switches over from double locking to central locking.
The turn signal lamps flash to confirm when the vehicle has been double locked.
The turn signal lamps do not flash when the vehicle is centrally locked.
Locking/unlocking – central unlocking
The central unlocking system unlocks all of the doors on the vehicle including the liftgate.
If the vehicle has been configured for unlocking via the driver's door lock and the "unlocking" button on the remote control is only pressed once, then just the driver's door is unlocked.
If the "unlocking" button on the remote control is then pressed again within 3 seconds the remaining doors are unlocked via the central unlocking function.
If the vehicle was double locked beforehand, then the other doors are centrally locked, whereas the driver's door is unlocked.
Unlocking of the vehicle with the ignition switched off, is confirmed by one long flash of the turn signal lamps.
Locking/unlocking - automatic re-locking function
The automatic re-locking function returns the locking system of the vehicle to its last status if it was centrally locked or double locked and the following conditions are satisfied:
- The vehicle is unlocked via remote control.
- Neither a door nor the liftgate has been opened within 45 seconds.
- The ignition is not switched on.
Liftgate
The liftgate unlocking mechanism unlocks the liftgate if the ignition switch is either in position "0" or position "1" and one of the following conditions is met:
- The liftgate unlocking button on the outside of the vehicle is pressed, provided the vehicle has been unlocked either via the driver's door lock or centrally.
- The liftgate unlocking button on the remote control is pressed once (provided the vehicle has been configured for liftgate unlocking after a single press of the button on the remote control).
- The liftgate unlocking button on the remote control is pressed twice within 3 seconds (if the vehicle has not been configured for liftgate unlocking after a single press of the button on the remote control).
If the liftgate is unlocked via the remote control while the vehicle is locked then it is automatically locked again when the vehicle is re-locked.
Keyless vehicle system
A keyless vehicle module for locking and starting is available as an option. With this system, receivers on the two front door handles and at the rear of the vehicle check whether a valid "Passive Key" which has been programmed for the vehicle is present in the detection area in order to prepare the locking mechanism for opening of the doors.
Subsequently, sensors in the interior detect whether a valid "Passive Key" which has been programmed for the vehicle is present in the detection area in order to enable the ignition lock after operation of the clutch pedal (vehicles with a manual transmission) or brake pedal (vehicles with an automatic transmission).
The reception signals are transmitted to the keyless vehicle module, which then controls all further locking/unlocking functions.
Depending on how the system is programmed, operation of the driver's door handle will unlock either all of the doors or just the driver's door. If the vehicle is programmed for "single door unlocking" and other door handles are operated in addition to the driver's door handle then the vehicle is centrally unlocked.
After leaving the vehicle, it can be locked via sensors on the front door handles or on the liftgate handle (press once) or double locked (press twice). In this case, a request signal (lock/unlock) is transmitted by the keyless vehicle module to the GEM via the mid-speed CAN bus. The GEM then actuates the door modules via the mid-speed CAN bus, which unlock or lock the vehicle.
All door opening/closing functions can also be performed via the remote control buttons on the "passive key". In addition, there is an emergency key in the "Passive Key" which, together with an adapter, serves to open and start the vehicle in an emergency.
Passive Start
A keyless vehicle module for starting is available as an option. With this system, sensors in the interior detect whether a valid "Passive Key" which has been programmed for the vehicle is present in the detection area in order to enable the ignition lock after operation of the clutch pedal (vehicles with a manual transmission) or brake pedal (vehicles with an automatic transmission).
Once the ignition lock has been enabled, the vehicle can be started via the starter button in the dash panel console provided the transmission is in neutral and the clutch is fully depressed (vehicles with a manual transmission) or provided the transmission is set to "Park" and the brake pedal is fully depressed (vehicles with an automatic transmission).
The starter button is pressed again to switch the engine off, whereby the vehicle speed must be below the maximum limit of 7 km/h.
The engine can be stopped at any vehicle speed by pressing and holding the starter button or by pressing it repeatedly.
It is possible to restart the engine within 10 seconds of switching the engine off without repeat detection of a valid "Passive Key". The only requirement in this instance is that the correct pedal for the type of transmission is depressed.
If a valid "Passive Key" which has been programmed for the vehicle is in the detection area of the ignition lock and the starter button is pressed without the clutch pedal (vehicles with manual transmission) or brake pedal (vehicles with automatic transmission) being depressed, the ignition only is switched on but the engine cannot be started. Pressing the starter button again switches the ignition back off.
Smart Charge system
In addition to the familiar functions, the Smart Charge system also performs the following functions:
- Automatic deactivation of non-critical high power electrical consumers when the battery voltage is low in order to reduce the level of current drawn.
- Automatic activation of non-critical high power electrical consumers when the battery voltage is excessively high in order to protect components which are sensitive to increased voltages.
The battery charging current is optimized through continuous calculation of the battery temperature and monitoring of the alternator output voltage.
By receiving the forwarded alternator load signal, the PCM is given early warning whenever an electric consumer is switched on or off. This means that the PCM receives information about imminent changes in the torque drawn by the alternator. By evaluating this information the PCM can provide a higher level of idling stability.
The two remaining functions of the Smart Charge System are controlled by the GEM.
Electrical consumers are switched off due to low voltage when the GEM determines (on the basis of the message received from the PCM on the CAN bus via the instrument cluster) that the battery voltage has dropped below the threshold.
When the threshold for low battery voltage is reached the GEM automatically deactivates the following consumers - in this order and with a gap of 5 seconds between each:
- Electric booster heater (vehicles with diesel engines)
- Heated exterior mirrors
- Heated rear window
- Heated windscreen
If the battery voltage rises back above the lower threshold then the GEM re-enables all of the electrical consumers which were previously disabled. They then have switched off status and must be switched back on by the driver.
Electrical consumers are switched on due to excessively high voltage if the GEM determines that the battery voltage is above the threshold for overvoltage and the charge control lamp has been switched on.
When the threshold is reached the GEM automatically activates the following consumers - in this order and with a gap of 5 seconds between each:
- Heated rear window
- Heated exterior mirrors
- Electric booster heater (vehicles with diesel engines)
- Blower motor
If the battery voltage drops back below the threshold then the GEM automatically deactivates any consumers that were switched on. However, if they were switched on by the driver before the automatic activation, they will then be switched on again in turn with a 5-second time interval.
Ignition overload protection
The ignition overload protection intermittently disconnects certain circuits in order to restrict the current being drawn from the battery while the starter motor is operating.
The position of the ignition switch is transmitted by the instrument cluster on the MS CAN bus.
The ignition overload protection relay which is integrated in the battery junction box is activated by the GEM when the message "ignition switch position III" is received from the instrument cluster.
Electric window regulators
The ignition key must be in position "II" before the electric window regulators can be operated. The electric window regulator open or close the door windows when the switch is moved to the corresponding position.
The movement of the window glass stops when the window regulator button is released or when the ignition key is moved from position "II" to position "I", "III" or "0".
The driver door window can only be operated via the driver door switch; the other windows can be opened and closed via the driver door switch panel or the relevant door switch.
If the window on the front passenger's door is operated via the switch on the switch panel in the driver's door, then the driver's door module receives the cable-transmitted signal from the switch and forwards it on the CAN bus to the door module of the front passenger's door, which then moves the window glass to the corresponding position.
The rear doors are each connected via a LIN bus to the door modules of the front doors.
The disabling switch in the switch panel on the driver's door can be used to disable the window regulator switches in the rear doors.
NOTICE:
If the navigation system display module is to be removed for testing or
new component installation, remove any audio media (if possible) from
within the navigation system display module and return it to the
customer. Failure to follow this instruction may result in damage to the
navigation system display module.
