The receiver of the GPS satellite navigation system supplies the navigation computer with the current vehicle position in degrees latitude and longitude.
A CD with map data is loaded in the CD drive of the navigation computer. The navigation computer combines the vehicle position calculated by the GPS with this map data.
The driver can enter a destination. The navigation computer calculates a route from the current location to this destination based on selectable criteria (main trunk roads, shortest distance, etc.).
With the aid of arrow indicators and distance data on the navigation radio and a voice output function, the navigation computer indicates how and where to get into the correct lane or turn off while the vehicle is moving.
The navigation computer calculates the distance covered from the signals from an ABS wheel speed sensor.
An inertia sensor, known as the ”GYRO”, informs the navigation computer about rotary movements of the vehicle (e.g. when turning off etc.). This gyro sensor is fitted in the casing of the navigation computer.
The magnetic-field probe familiar from navigation system 1 is eliminated and replaced by the gyro sensor.
An alternative route is recalculated automatically if the driver does not follow the route instructions.
A CD drive is integrated in the navigation computer. The navigation CD is loaded in this drive.
The navigation computer also features a fan. If the cooling capacity of the fan is not sufficient, the navigation computer is switched off due to overheating.
The gyro sensor is an inertia sensor which records the forces which occur during a change in direction and transfers this data to the navigation computer in the form of a voltage change. This gyro sensor is fitted in the casing of the navigation computer.
The Global Positioning System is a system which was originally developed for military use, in which approx. 20 satellites in earth orbit send position-related signals. These signals are evaluated by a computer specially developed for this purpose and converted into a position. The accuracy of the system varies, however, it is at least within 20 m.
GPS reception is only possible when unobstructed view of the sky is ensured.
GPS, in conjunction with the BMW navigation system, consists of an aerial and a receiver which evaluates the satellite data received via the aerial and transfers the calculated vehicle position to the navigation computer.
The navigation computer evaluates the signals of an ABS speed sensor (E46 and E52, rear left wheel) and uses this to determine the distance driven.
The data the navigation computer requires for route planning is stored on the navigation CD. It is advisable to use the latest updated version in order to take account of any changes in the road system.
The navigation system can only be selected if a navigation CD has been inserted in the drive.
The acoustic signals are transferred via 2 AF lines directly to the radio.
The display data is routed via the NAV bus to the LC display.
The user interface, i.e. the menus on the LC display, is set up by the navigation computer.
A new version of the operating software offered by BMW should be loaded as follows (refer also to instructions on the CD):
Important
Do not change the terminal setting during the loading procedure! Ensure adequate voltage in the vehicle electrical system.
Proceed as described below to install the navigation computer:
The vehicle must not be moved or be subject to vibration during this waiting period.
Reason:
Every time the navigation computer is restarted, it recalibrates its gyro sensor (inertia sensor). The gyro reacts to any movement. This means that the first calibration, which takes place during insertion of the computer in the bracket, leads to defective values.
For this reason, the navigation computer - even before the vehicle moves - has to be made to run a new gyro calibration. This takes place by resetting the K bus as described above.
The operating software must be loaded first prior to encoding the navigation computer
Initialization may also be necessary on vehicles with BMW Assist
After the navigation computer has been replaced, a test drive lasting approx. 15 minutes is necessary, during which GPS reception must be ensured.
In the navigation computer MK2, the GPS receiver is installed in a separate housing.
In the case of navigation computers MK3 and MK4, the GPS receiver is integrated in the navigation computer.
Components
In the E52, the MIR is fitted without the cassette component.
In the E46, the MIR is fitted with the cassette component.
Components
The MIR consists of the radio component and an operating unit integrated into one device. Two diagnosis addresses are provided for diagnosis purposes so that the radio and operating unit can be diagnosed separately.