Navigation System Components
The navigation system contains the following components:
• | The navigation interface module (NIM) |
• | The global positioning system (GPS) antenna |
These components then integrate and communicate with the following components:
• | The infotainment module |
• | The steering wheel controls |
• | The body control module (BCM) |
Navigation Module
The navigation module is available in 2 different variants. Both are single
DIN units designed as external components which can be installed as part of the infotainment
system. The navigation module is mounted in the instrument panel compartment and contains
all the navigation engines and gyroscope used to detect movement of the vehicle.
Type A Navigation Module
This navigation module features 'Turn by Turn' directions. The navigation module
is an optional accessory to low level vehicles fitted with Type A or C infotainment
systems. The navigation module transmits 'Turn by Turn' direction symbols to the instrument
cluster display, via serial data to the navigation interface module (NIM) before being
translated and re-transmitted via GMLAN. The navigation module also sends audible
verbal direction to the speakers through the infotainment unit via the NIM. Key entries
are entered via the steering wheel remote control.
Type B Navigation Module
This navigation module features 'Turn by Turn' directions as well as displaying
full map and routing information on the infotainment unit display. The navigation
module is an optional accessory to high level vehicles fitted with Type D infotainment
systems featuring 6.5" colour LCDs. The navigation module transmits 'Turn by
Turn' direction symbols to the instrument cluster display, via serial data to the
navigation interface module (NIM) before being translated and re-transmitted via GMLAN.
The navigation module also sends audible verbal direction to the speakers through
the infotainment unit via the NIM. Map based navigation routing information is also
channelled directly to the infotainment unit display from the navigation module. Key
entries are entered via the infotainment unit fascia. The INFO button on the steering
wheel is used to recall the last audible direction, and also displays the function
on the instrument clusters centre multi-function display.
Navigation Interface Module (NIM)
The navigation interface module (NIM) is used to communicate data between the
navigation module and the vehicle body control module (BCM), the instrument cluster
and the infotainment unit. The illumination signal and ignition signal messages are
sent from the BCM to the NIM via GMLAN, the NIM then translates these signals and
re-transmits the data to the navigation module. The odometer and reverse signals are
also transmitted to the navigation module via the NIM. The NIM also translates and
re-transmits the mute signal from the navigation module via serial data to the infotainment
unit. The NIM is mounted to the inside edge of the instrument panel insulation panel,
directly beneath the I/P compartment.
Global Positioning System (GPS) Antenna
The global positioning system (GPS) locates the current position of the vehicle
using signals sent by GPS satellites. The GPS antenna is attached to the instrument
panel (I/P) carrier and can be accessed by removing the I/P centre air outlet grille
assembly. The GPS antenna is powered through the same coaxial cable used to send the
signals to the navigation module. Interference to the system may occur if any of the
following exist:
• | Signal shadowing, when signals are obstructed by objects such as tall
trees or buildings. |
• | Metallic objects located on the dashboard. |
• | Aftermarket glass tinting has been applied to the vehicles windshield. |
• | Ionospheric disturbance (caused by solar activity, which results in greatly
increased radio wave absorption). |
• | Atmospheric disturbances caused by stormy weather. |
• | Proximity to high power distribution locations, i.e. sub-stations, power
stations. |