Instrument Cluster / Carrier: Description and Operation
Instrument Cluster
INSTRUMENT CLUSTER - COMPONENT LOCATION
OVERVIEW
The instrument cluster for 2010MY is an all new high definition Thin Film Transistor (TFT) display.
Designed to look similar to a conventional instrument cluster for the main display, the new display can be continually reconfigured to prioritize and refine the information presented to the driver. All displays are 'virtual' gauges with the speedometer and the tachometer being the dominant features of the new display. Only 2 hardwired warning indicators remain; the airbag warning indicator and the security warning indicator. Both of these indicators are LED (light emitting diode)'s.
Two ambient light sensors; one on either side of the pack, (to ensure the brightest lighting conditions are detected) are used to adjust cluster illumination in response to prevailing lighting conditions.
The instrument cluster features a number of warning indicators. The warning indicators illuminate in one of four colors which indicate the level of importance of the warning as follows:
- Red = Warning
- Amber = Caution
- Green = System operative
- Blue = Headlamp high beam operative.
A feature and driver preference menu is available to allow the driver to select certain features and functions of the instrument cluster and change them to their personal preference. A menu control 'joy pad' is located on the RH (right-hand) side of the steering wheel and allows selection of the displayed functions and navigation of the menus. When selected, the menu is displayed in the center of the TFT screen which allows access to a number of vehicle functions.
DESCRIPTION
Warning Indicators
Warning Indicators - All Markets Except NAS
Warning Indicators - NAS
The warning indicators are mainly located in 3 groups; one in the speedometer display, one in the tachometer display and one group in a central position at the top of the TFT screen. A number of warning indicators are also located outside of these areas as shown on the illustrations.
There are 2 SRS (supplemental restraint system) warning indicators used. The primary SRS (supplemental restraint system) warning indicator is located on the LH (left-hand) side of the cluster and is a hardwired LED (light emitting diode). A secondary SRS (supplemental restraint system) warning indicator is located to the bottom left of the speedometer and is only used in case of failure of the primary warning indicator for legislation requirements.
A hardwired LED (light emitting diode) is located on the RH (right-hand) side of the cluster and is used for the security LED (light emitting diode).
TFT Display
During a typical journey new events and priority messages can be continually updated on the display as and when required. For example, audio information displayed centrally can be replaced with the navigation instruction information or 4x4 information can be displayed in off road situations.
To ensure the brightest lighting conditions are detected, 2 ambient light sensors are located on each side of the cluster. They are used to adjust cluster illumination in response to prevailing lighting conditions. The cluster also has high-output bright LED (light emitting diode) backlighting and a smoked 'glass' screen which helps prevent washout by reducing the amount of sunlight that can reach the screen directly. The TFT display screen also incorporates an anti-glare coating.
The full TFT screen measures 312 mm (12.3 inches) across its diagonal corners and is specified with 1280 horizontal and 480 vertical pixels. Because of the design of the instrument cluster binnacle, not all of the screen is visible but the graphics are designed to display within the viewable area.
Start-Up Screen
When the vehicle is locked the display goes off. When the vehicle is unlocked the display slowly illuminates to show the background image and display key information to the driver.
Pressing the stop/start button will initiate a full build of the screen display to display the speedometer and tachometer and also the warning indicators. When the engine is running a range of applicable instruments, messages and warning indicators will be displayed.
Event Screens
A large number of differing permutations of screens are available to cover all possible combinations of the available functions. The above illustration shows the 4X4 screen, but other screens are available to cover a range of vehicle functions.
Certain vehicle functions will overwrite the existing information displayed. Certain displays may move or be replaced to allow room for other displays as shown in the 4X4 display above. For example, the speedometer may move to the right a little to allow room for important vehicle functional to be displayed.
A number of features are also used to convey information to the driver. For example, if speed control is selected, the set speed is displayed as a marker in the speedometer outer ring.
Instrument Cluster Menu
The instrument cluster menu is only visible when any part of the menu control has been pressed. Menu selections can be made using the menu control to select the required menu option.
When the required selection is highlighted, pressing the 'OK' button will select that option. The screen will then display a sub-menu for that option or activate the selected item. Scroll arrows to the left of the menus allow the menu to be moved up or down to menu items that are not visible in the current view. If the arrow is displayed brightly this indicates that additional menu items are available in that direction.
The menu can be closed by pressing the left button on the menu control. If sub-menus are open, pressing and holding the left button on the menu control will close the sub-menus. The menu will close automatically if:
- no selection is made in the main menu within 10 seconds of opening
- a selection is made in the main menu and no further selection is made within 4 minutes. If a selection is made within the 4 minute period, the timer will reset and a further 4 minutes will elapse before the menu automatically closes if no further selections are made.
The current menu can be exited or to move from a sub-menu without making a selection, press the left arrow on the menu control.
The following table shows the available menus and sub-menus and the options available within each menu.
Instrument Cluster Cooling Fan
Due to the location of the instrument cluster, in hot climatic conditions there is a risk of over-temperature affecting performance. A cooling fan is used to maintain the temperature at an acceptable level. The fan is located near the steering column and blows air into ducting which is connected to the rear of the cluster. The ducting also channels air into the rear of the Touch Screen Display (TSD). The temperature is monitored internally within the instrument cluster and the fan is activated by the instrument cluster via a PWM (pulse width modulation) signal.
If instrument cluster temperatures are high, the fan can continue to operate for up to 5 minutes after the ignition is turned off to assist with cooling of the cluster and/or the TSD.
If a failure of the fan occurs, the instrument cluster has internal temperature sensors which will detect overheating and progressively reduce the backlighting of the display to reduce the heat generated within the cluster. In this way the cluster will self-limit the temperature to avoid overheating, at the expense of a loss of brightness at high temperatures.
OPERATION
Control Diagram
NOTE:
A = Hardwired; D = High Speed CAN bus; N = Medium speed CAN bus; O = LIN bus
Three processors within the instrument cluster manage communications between the vehicle and the cluster display and incorporate the operating software required to drive screen re-configurations.
The instrument cluster receives a permanent fused supply from the passenger compartment fusebox. The same power feed also provides a power supply to the instrument cluster cooling fan.
The cluster is connected to other vehicle systems and control modules via the medium speed CAN (controller area network) bus, high speed CAN (controller area network) bus and LIN (local interconnect network) bus connections.
The majority of information is passed to the instrument cluster from other system control modules on the high speed and medium speed CAN (controller area network) buses and also the LIN (local interconnect network) bus. However, some vehicle sensors are hardwired directly to the instrument cluster.
The security LED (light emitting diode) is controlled by a hardwired connection from the CJB (central junction box). A Field Effect Transistor (FET) within the CJB (central junction box) controls the output to the LED (light emitting diode).
The steering lock control module is connected to a hardwired connection to the instrument cluster. Security information from other control modules is passed via the network buses and when the conditions are correct the instrument cluster instructs the steering lock control module to unlock the steering column.
The clockspring is connected to the instrument cluster on a LIN (local interconnect network) bus connection. The LIN (local interconnect network) bus passes driver selections made on the steering wheel mounted switches to the instrument cluster for processing and transmission to other control modules.
The instrument cluster cooling fan is connected to the cluster with three wires. One wire provides the fan motor ground. The remaining 2 wires provide a monitor feedback to the cluster and a PWM (pulse width modulation) output to control the fan speed.