On-board monitor system

There are three diagnosis programs for the components of the on-board monitor system:

• Video module (incl. LCD monitor)
  
• On-board monitor control panel
  
• Navigation system
  

On-board monitor system

Information relating to on-board computer, GPS navigation, television, video recorder, video text, radio, telephone, independent heating/ventilation and sound control can be displayed on the on-board monitor.

The on-board monitor system consists of the following main components:

• On-board monitor control panel (BMBT):
  The control panel for the on-board monitor is the keypad with which the on-board monitor system is operated. The key functions are routed via the I-bus to the relevant control units.
  
• LCD monitor:
  The LCD monitor is integrated in the control panel (BMBT). It receives all screen information from the video module (VM).
  
• Video module (VM):
  The video module generates video signals and routes them to the LCD monitor. The video module forwards sound signals such as TV sound and navigation sound to the radio.
  
• Navigation processor (if GPS navigation installed as optional equipment):
  Once the driver has entered a destination, the navigation computer can calculate a driving route from the current location and provide related visual and acoustic information. Various sensors supply information regarding the current position, vehicle direction and route.
  
• Radio
  The radio is operated from the control panel for the on-board monitor via the I-bus. It features inputs for the cassette and TV/navigation sound line. The speakers or DSP amplifier (optional) are connected to the output.
  The DSP amplifier supplies high output to the 16 speakers connected to it and provides optimum sound quality.
  

The individual components are linked as follows:

• The on-board monitor control panel and video module are interlinked via the I-bus.
  
• The navigation computer is connected to the video module by means of a separate data link (ARCNET), i.e. it is not a direct I-bus user.
  
• The video signals from the video module are transferred via 3 shielded lines (RGB) to the LCD monitor.
  
• The background lighting is controlled by a line between the on-board monitor control panel and LCD on-board monitor.
  

On-board monitor control panel (BMBT)

Function

The control panel for the on-board monitor is the keypad with which the on-board monitor system is operated. The key functions are routed via the I-bus to the relevant control units.

The radio and telephone are also operated via the on-board monitor control panel.

The cassette drive which is controlled from the radio is accommodated in the on-board monitor control panel.

Only one connection line leads to the LCD monitor for switching ON/OFF and for controlling the brightness of the LCD on-board monitor (PL line).

The LEDs are activated by I-bus data telegrams from the corresponding control units (telephone, radio, independent heating).

The on-board monitor control panel switches the LCD on-board monitor ON and OFF via the PL line. The PL signal serves the purpose of controlling the background lighting of the LCD screen.

• LCD screen ON: As of ignition lock position 1 or after pressing key with alarm function (e.g. pressing CLOCK key)
  
• LCD screen OFF: By switching the ignition lock to 0 position or after selecting the menu point "Screen OFF".
  

Components

The on-board monitor control panel consists of:

• Keypad for operating the on-board monitor functions and audio system
  
• Cassette drive for audio cassettes
  

Video module and LCD monitor

Function

The video module is a separate control unit which generates the pictures for the LCD monitor. For this purpose, it receives information from various other control units and processes it accordingly. The video module routes the pictures via RGB lines to the LCD monitor. The LCD monitor then displays these pictures.

Components

The video module includes the

• TV receiver with video text
  
• graphics stage,
  which produces the pictures displayed on the LCD monitor for the on-board computer, radio, DSP amplifier, telephone display and navigation system.
  
• aerial diversity:
  The TV aerial system consists of 2 fields in the rear window heating system. A separate aerial amplifier is installed for both aerials. The video module provides the voltage supply for the aerial amplifiers. Both aerials are connected to the video module, in which the diversity function is integrated.
  
• Selector switch for TV, video recorder and navigation system.
  

Note

The system also has provisions to facilitate connection of a further TV monitor and a commercially available video recorder. The video module is controlled via the I-bus.

Note

The on-board monitor is switched off at a voltage of < 8V or a temperature > 65 °C. The background lighting is controlled by the on-board monitor control panel via the PL-line.

Navigation system

Function

The navigation system is an additional, optional feature of the on-board monitor system. The driver can display road maps at various scales on the on-board monitor. In addition, it is possible to enter a destination, for which the navigation computer calculates the most favourable route based on the current location. This route can then be shown on the map as required.

While driving, the computer provides visual information, based on the current location, in the form of turning arrows and acoustic indicators for the proposed route, such as turn-off information with the distance to the next junction as well as requests to file into correct lane in good time. If the driver does not follow this suggestion, the navigation computer will propose an alternative route.

The navigation computer located in the rear left of the luggage compartment features a CD drive in which a CD with the stored road maps is loaded.

The system is operated via the on-board monitor control panel, the navigation computer controls route planning, the acoustic indicators and visual displays are generated by the video module.

A GPS (satellite) receiver (GPS = Global Positioning System) supplies the current position.

In addition, the navigation computer receives information on the driving direction from a magnetic field sensor, the distance covered from the ABS control unit and whether reverse gear is engaged from the light module or reversing lights.

The system only operates when a road map CD is loaded and in the areas, for which maps are stored on the CD.

Note

Generally, care must be taken to ensure that no metal objects (e.g. umbrellas) are placed in the area of the rear window shelf since they could impair operation.

Components

The navigation system consists of the following components and processes the following signals:

• Navigation computer with CD drive
  
• Road map CD
  The map CD contains a digitized road map. The navigation system can only operate when a road map CD is inserted.
  
• ABS control unit/speed sensor
  The navigation computer receives information from the ABS control unit concerning the distance and curve radius covered.
  
• Magnetic field sensor
  The magnetic field sensor is fitted in the rear window shelf and supplies the absolute driving direction.
  
• GPS
  
  The GPS (G lobal P ositioning S ystem) consists of the satellite aerial incorporated in the rear window shelf and the GPS receiver which evaluates the signals received by the aerial and calculates the current position.
  Reception can be interrupted temporarily by shadows in the direct link between satellites and vehicle caused by large buildings or natural obstructions (multistory buildings, trees etc.).
  The following information is provided on the GPS logo (black square at top right edge of map):
  Apart from the globe, the display field is black.
  Currently no signal is received from any satellite (e.g. possible in workshops). If this situation occurs more frequently and also in areas, in which, based on existing building structures, satellite reception should be possible, then this indicates a fault. Carry out troubleshooting in diagnosis program with symptom "GPS problems".
  Small white dots visible in display field next to globe:
  The number of white dots corresponds to the number of satellites from which signals are received. However, the number of satellites is too low or the position of the satellites is unfavourable such that the current position cannot be calculated.
  A green satellite symbol is shown above the globe in the display field with "GPS" indicated below it. A sufficient number of satellite signals is received in order to determine the position exactly.
  
• Reverse signal
  The navigation computer receives the "reverse" signal via the output of the light module for the right-hand reversing light. This is required in order to determine whether the distance is covered by driving in forward direction or in reverse.
  
• Rear window heating (defogger)
  Since the magnetic field generated by the rear window heating influences the measurements of the magnetic field sensor, the information "rear window defogger ON" is supplied to the navigation computer in order to compensate for the interfering variable.
  

Note

To start the troubleshooting procedure, select Point 1 "Restart diagnosis" following the identification page. In the case of fault symptoms related to positioning errors, a sensor test involving a precisely defined test drive is required in the majority of cases (refer to calibration run for detailed description and prerequisites). This is indicated on the DIS after entering the fault symptoms. The vehicle is disconnected from the DIS in order to carry out the sensor test. Once the sensor test has been completed successfully, continue troubleshooting by selecting Point 2 "Sensor test completed, continue diagnosis" after the identification page.