The navigation system works out the route and provides the directions to a defined destination.
GPS Navigation (Global Positioning System): The GPS navigation system pinpoints locations by means of the signals transmitted by satellites. The signals are received by the GPS aerial on the vehicle, processed by the GPS receiver and passed to the navigation computer as latitude and longitude data. The navigation computer uses this data to calculate the vehicle position with an accuracy of at least 100 m. By including the travel distance on straight stretches and on bends in the position calculation, the navigation computer improves the vehicle position specification. The difference between the calculated and actual vehicle position is then reduced to less than 10 m.
Correct operation of the GPS navigation system is only possible when there is an unbroken line of sight between the GPS aerial and at least two GPS satellites. This means that in underground car parks, tunnel, etc. there is no disrupted GPS.
The GPS aerial receives the signals from the satellites. The signals are passed to the navigation computer. The GPS aerial is fitted under the side section at the front left.
The navigation computer fitted under the rear seat on the right-hand side; it is cooled by an integral fan. If there is insufficient cooling, excess temperature leads to deactivation. The deactivation is indicated by a message on the Control Display (CD) and is entered as a fault code memory entry in the navigation and ASK.
A GPS receiver and a CD /DVD drive as well as a gyro are integrated in the navigation computer.
The gyro (inertia sensor) registers the force that occurs in a change of direction (drift), e.g. when taking a turn-off. The voltage signal resulting from the force detected is fed to the navigation computer. The navigation computer evaluates the signal changes resulting from the changes of direction.
The navigation computer is a node in the MOST network.
The data which the navigation computer requires for route planning is stored on the map CD/DVD.
Note: Handle the map CD/DVD with care. Scratches can lead to malfunctions. A scratched CD/DVD can cause a malfunction on one navigation system but not on another.
The wheel-speed sensor sends signals to the navigation computer from which it calculates the distance travelled. The standstill pulse is also displayed in the diagnosis request. The pulses can fluctuate between 0 and 1 at a standstill. The number of pulses rises with the wheel speed.
The Control Display (CD) and Central Information Display (CID) are separate components. The Control Display (CD) with the Central Information Display (CID) and the Controller (CON) contains the operation and display elements for the vehicle electronics, with the exception of the Audio Display Panel functions.
The Control Display (CD) co-ordinates the function requests from the system and assigns them to the individual functions. For the Control Display (CD), the following is displayed on the tester:
The Central Information Display (CID) is the display unit. For the Central Information Display (CID), the following is displayed on the tester:
The Controller (CON) is the control element for the Control Display (CD) with the display unit Central Information Display (CID). To run operating functions, the front Controller (CON) is folded out of the centre armrest.
On the instrument cluster, in conjunction with the navigation display on the Central Information Display (CID), navigation displays can also be shown.
The audio system controller (ASK) is a control unit in the MOST network. The audio system controller (ASK) manages all the audio signals.
The MOST (Media Oriented Systems Transport) bus transmits the audio, video and navigation signals.
The RGB lines (red-green-blue lines) are used to transmit video signals to the control display.
The navigation computer calculates the vehicle's location by analysing data from
Note: In the case of battery disconnection and undervoltage, the location (almanac) is lost. Recalculation of the location takes approx. 3 minutes.
The Match function continually compares the current vehicle location with its expected position along the route. Discrepancies identified are corrected.
After a tyre change, the navigation system automatically learns the correction factor for the tyre size while the vehicle is being driven. There may be incorrect location calculation during the correction. The learning procedure is completed after a few miles.
The navigation computer calculates the required route from
So that the displayed routes correspond to the current routing of the roads, a map CD/DVD with the current values must be inserted in the CD /DVD drive.
To calculate a driving route using the Controller (CON) on the Central Information Display (CID) enter or select:
Note: Extensive deviations in the display to the actual route indicate GPS reception problems or problems with the gyro. Disturbances of this nature have an effect on long straight-ahead trips, e.g. on motorways.
The navigation system can only be selected from the Controller (CON) if a map CD/DVD has been inserted.
For the display of navigation data on the Central Information Display (CID), there is a choice between
Acoustic directions to turn-offs are output via the audio system controller (ASK).
Note: An alternative route is recalculated and displayed automatically if the driver does not follow the route instructions.
In addition to the display on the Central Information Display (CID), the following can be displayed in the revolution counter of the instrument cluster:
Until shortly before the next turn-off, the distance to it is shown in figures. It is then shown in the form of a bar indicator. The bar shrinks continuously as the turn-off approaches.
Whether the distance to the next turn-off is shown in figures or graphically is decided by the navigation system.
A new version of the operating software is loaded as follows (refer to instructions on the CD/DVD):
Note: Load the operating software first!
The operating software must be loaded first prior to encoding the navigation computer.
Location calculation is performed among others with the GPS receiver. It is vital that the navigation control unit is supplied with power. The power supply is checked by selecting navigation. Observe Help for MOST network. The unit has GPS reception if the globe in the Central Information Display (CID) has a green background. In order to have GPS reception, the vehicle must be located in an open outdoor space. If no reception is possible, the aerial must be checked. Important for the GPS aerial is the power supply of 5 V and the diagnosis requests.
If the MOST framework is working but the navigation cannot be activated, the software of the control unit must be checked. The navigation has no effect if there is overheating.
Note: Scratches on the CD/DVD can cause system crashes or function loss. If a symptom of this nature appears, run an operational test with a new or undamaged CD/DVD. A CD/DVD that works in a navigation computer without complaint is not necessarily free of faults.