Instrument cluster with on-board computer and control panels

For all other control units, the instrument cluster is the ”time” and ”dimmer master”. The time and brightness information is supplied to the other control units as a telegram. The data exchange between the instrument cluster with its components and control panels and the vehicle components is via:

• CAS, the Car Access System. The CAS is the gateway module between the data buses K-CAN SYSTEM and K-CAN PERIPHERIE.
  
• ZGM, Central Gateway Module The ZGM connects the BYTEFLIGHT, K-CAN SYSTEM, PT-CAN data buses and the DIAGNOSTIC BUS.
  
• K-CAN SYSTEM data bus The K-CAN SYSTEM data bus connects the instrument cluster and the control units in the chassis and suspension, drive and body sections.
  
• MOST bus The MOST bus connects the control units in the communications section (navigation system, ASK audio system controller, SVS language processing system, CD control display).
  

Control panels

Keys on the steering column switch centre

The keys for calling up and scrolling the on-board computer displays are located on the steering column switch centre.

Pressing the top key for a longer period toggles the display in the display area below the revolution counter. Each long press toggles between the functions Check Control and on-board computer.

Brief pressing of the top key scrolls the displayed function.

Brief pressing of the lower key scrolls through all the display options below the speedometer.

Long pressing switches both display simultaneously bright or dark when

no message of the Check Control is active (e.g. engine overheating) or

the fuel gauge is at ”Reserve”.

Controller

The on-board computer is operated by means of the controller located on the front centre armrest.

Trip odometer reset button

The instrument cluster contains the trip distance reset button, which can also be used to start functions.

Brief pressing of the trip distance reset button with the ignition switched off enables the following functions to be run and displayed for eight seconds:

• Total mileage and trip distance
  
• Time
  
• Outside temperature
  

The displayed trip distance is reset when the trip odometer reset button is pressed again within this period.

Pressing the trip distance reset button for a longer period (> two seconds) with the ignition switched off triggers the following functions:

• The ABS ISO symbol is displayed in the variable warning field for two seconds (US market).
  
• The test functions are activated.
  
• Die SBA service indicator is reset.
  

Only the display areas inside the speedometer and the revolution counter are backlit.

Dimmer wheel

The dimmer wheel is used to select the LCD brightness (backlighting brightness).

Instrument cluster

The instrument cluster contains not only the control panel but also the display elements, two CPUs and a control unit:

• Display elements: LC display, pointer instruments, indicator lamps with fixed positions
  
• Computer for the display, lighting, on-board computer and Check Control functions
  
• Computer for activating the needle instruments and the permanently installed indicator and warning lamps.
  
• Control unit: conversion of the input and output signals in the signal format.
  Directly at the instrument cluster:
  
  • Outside air temperature sensor and
    
  • Sensors for wash water level, coolant level and tank level
    

Country-specific version

The instrument cluster is produced in different hardware versions for different markets. Various displays, languages and units can be set using the Control Display.

Europe with language extension: This version contains additional characters for Japan, Korea, Taiwan. Speedometer with km/h scale, revolution counter for petrol engine with scale up to 7000 rpm, memory capacity 8 MB

Europe: Speedometer with km/h scale, revolution counter for petrol engine with scale up to 7000 rpm, memory capacity 4 MB

Europe and US market: Speedometer with mph scale, revolution counter for petrol engine with scale up to 7000 rpm, memory capacity 4 MB

Languages: The following languages are stored in the 4 MB language memory of the instrument cluster: German, English (UK), English (US), French, Italian, Dutch, Spanish.

In addition to the above mentioned languages, the following languages are stored in the 8 MB language memory of the instrument cluster: Japanese, Korean, Chinese (traditional), Chinese (simple).

Language coding: the language coding is dependent on the country coding of the Car Access System (CAS). A language package is programmed in the Control Display, containing three of the languages listed above. From these three languages, one language can be selected for the control display. The settings can be stored as a key memory function. In this ways, the units and languages stored are displayed as a function of the key used (user).

Unit conversion: Units can be converted by means of encoding with the Tester or at the control display:

• Consumption (mpg US, mpg UK, km/l, l/100 km)
  
• Temperature (°C, °F)
  
• Distance (km, miles)
  
• Date/time (date/time format US and Europe)
  

Display elements

• LC display: All the displays and messages (e.g. those of the on-board computer) are shown in the LC display, which is subdivided into six display areas.
  
• Needle instruments: Vehicle speed and engine speed are indicated by needle instruments which move over an LC display. The needles are driven by stepping motors.
  
• Fixed-position indicator lamps: The displays required by law are configured with permanently installed, standardized indicator and warning lamps.
  

The indicator and warning lamps as well as the backlighting of the LC display are designed as single- or multicoloured non-replaceable LEDs.

At temperatures < 10°C, display heating is switched on when the driver's door is opened. Switching on/off is also controlled by the consumer shutdown of the power module depending on the vehicle voltage.

Lighting and dimming

Lighting: The individual display areas and dials are only backlit when data is to be displayed in their areas.

EXCEPTION: Set speed limit.

The needles and graduated dials are only illuminated when the driving lights are switched on and thus also serve as function indicators for ”driving lights ON”.

The brightness setting of the LC display and all indicator and warning lamps changes automatically. It is adapted to the prevailing lighting conditions by means of a phototransistor. The brightness signal required for the adjustment is generated in the instrument cluster. A brightness signal is calculated from the values of the phototransistor and the dimmer potentiometer (setting of dimmer control wheel). The brightness signal is made available to all other control units as ”dimmer master” information.

Contrast: The contrast of the LCD display is set automatically depending on the LCD temperature at the instrument cluster and the operation period. To do so, control electronics are supplied with the temperature determined at the LC display by an NTC resistor as an input value. The time-dependent ageing is used as another input value. To achieve this, the non-operating and operating time of the instrument cluster is recorded with a built-in timer. The result of both input values is that a contrast voltage that automatically adapts to the operation conditions is generated.

Acoustic signals

A speaker is integrated in the instrument cluster to issue acoustic signals. The sound signals are generated by a built-in sound generator when the turn indicators are switched on, when the speed limit is exceeded and as a temperature warning.

All other acoustic signals are generated by the ASK audio system controller and output through the front left and right car speakers. Signals from the Check Control are made audible according to their importance as a gong or double gong. Volume and tone also correspond to the importance of the signal.

Display areas of instrument cluster

Display area 1: LC display

Display area 1, within the speedometer. Display of content as text and graphic:

• Speed limit: In order to prevent the speed limit from being exceeded, a speed limit can be entered in the on-board computer. Speed limits are displayed as a bright circle segment from the limit to the scale end. There is an acoustic warning on exceeding the limit.
  
• Step cruise control: Up to six speed marks can be set as ball-shaped marks. The set speeds can be stored and called up. Values that are often required can be selected by pressing a button without the driver having to approach the speed exactly beforehand.
  When cruise control is active, a bright arrow marks the speed at which the car is being controlled at that moment. If the function has been deactivated, e.g. by braking, the speed at which the car was last being controlled while driving is marked by a dark arrow.
  
• Diagnosis test function: The trip distance reset button can be used to select a total of 21 test functions in the display area within the speedometer. The content of the test function selected is shown in the display area inside the revolution counter.
  
• CBS Condition Based Service ”reset”: The trip distance reset button can be used to select the ”CBS reset ”functions in the display area within the speedometer. The content of the function selected is shown in the display area inside the revolution counter.
  

Display area 2, within the revolution counter. Display of content as text and graphic:

• Variable rpm early warning zone: In addition to the fixed rpm early warning zone (broken red line) and the fixed rpm warning zone (continuous red line), a variable rpm early warning zone can be overlaid below these markings. In this way, a maximum rpm recommendation is displayed depending on the engine operating state, and this goes out when the engine reaches normal operating temperature.
  
• Navigation display: The guidance indicator (round arrow), the next intersection and the distance to the next intersection are shown as navigation displays.
  Up to the next turn-off, numerical display of the distance, then with a bar chart. The bar shrinks continuously as the turn-off approaches. The type of display is determined by the navigation system.
  

Display area 3, below the speedometer. Display of content as text and graphic:

• SBA service indicator: If there are no messages from the SBA service indicator, the fuel gauge or the fuel range is displayed here (depending on the setting).
  
• BC on-board computer displays: By pressing the BC on-board computer button on the turn indicator and dipped-beam switch, it is possible to switch between the on-board computer displays.
  

Display area 4, below the revolution counter. Display of on-board computer and Check Control text messages:

On-board computer text messages are overwritten by Check Control text messages. Most text messages are supplemented by the overlay of a symbol matching the message in the variable display and warning field (display area 5).

Display area 5, variable display and warning field. Display of content as text or graphic:

• CC Check Control warning symbols: Each CC text message in display area 4 is assigned a symbol which shows up red or yellow in this area.
  If there are no incoming Check Control messages, the outside temperature and time are permanently displayed.
  
• Outside temperature: The display resolution is 0.5°C. If the temperature drops below +3°C, a message with an acoustic warning is issued.
  The displayed outside temperature is a calculated value. It is calculated by the instrument cluster, taking into account the coolant temperature and vehicle speed.
  
• Time: The quartz clock integrated in the instrument cluster can be manually set by means of the controller in the control display.
  In vehicles with a navigation system, the minute setting of the manually set time is corrected. The correction is on the basis of the UTC (United Time Coordinated) world time received by the navigation system.
  Only the deviation of the minute setting in the ±2.5 minutes range from the actual time is corrected by the navigation system. The hour display has to be set manually.
  A clock that is manually set outside the correction range runs as a normal quartz clock.
  Time and outside temperature are displayed from terminal R ON.
  

Display area 6, gear display: In the Steptronic mode, the gear engaged by the gearbox is displayed (M1 to M6). S is displayed here in driving program position D and with the S program activated.

Display area 2, needle instrument: Speedometer

The speedometer scale and the scale captioning are represented on the permanently arranged graduated dial. The needle is moved by a stepping motor.

Display area 3, needle instrument: Revolution counter

The speed indication is derived from signal sampled at the left rear wheel sensor and directed to the DSC control unit.

The revolution counter scale and the scale captioning are represented on the permanently arranged graduated dial.

The graduated dial features an rpm advance warning zone (broken red line) followed by an rpm warning zone (continuous red line). The needle is moved by a stepping motor.

The speed signal is sent from the DME to the instrument cluster.

Display area 4, indicator and warning lamps

The indicator and warning lamps are permanently arranged in between and next to the needle instruments. The symbols are backlit for display purposes by coloured and multicoloured LEDs.

In this way, the symbols show up red, yellow, green or blue, depending on their importance.

The standardized indicator and warning lamps required by law are:

• Turn signal light
  
• High beam
  
• Belt warning
  
• Airbag
  
• General brake warning
  
• Rear fog lights, front fog lamps
  
• OBD II Check Engine (MIL)
  

This area also contains the indicator and warning lamps for:

• DSC Dynamic Stability Control
  
• Program display of automatic transmission
  

Program display of automatic transmission

The arrows next to the program display (transmission program stages P, N, D, R) indicate the possible direction of movement of the transmission selector lever on the steering column.

The program display remains activated

• for 10 seconds after removal of the remote control (run-on function) a n d
  
• for up to 30 minutes with the engine switched off (terminal 15 OFF) and driving position N selected.
  

The 30-minute display serves as a reminder that position P was not selected when the car was parked. The parking gear is automatically activated after the 30 minutes have elapsed.

Full control of the program and gear display is performed by the EGS control unit.

All other indicator and warning information is displayed with the relevant symbol in the variable warning field.

Pre-drive check

The pre-drive check has two functions:

• It checks the internal functions of the instrument cluster and
  
• monitors the alive signals of all control units that can output a Check Control message.
  

To perform the functions

• all the fixed indicator lamps are simultaneously activated shortly after terminal 15 ON. EXCEPTION: Airbag is already activated from terminal R.
  
• and indicator lamps which can light up red and yellow (parking brake and brake warning) light up yellow first and then switch to red after approx. two seconds.
  

The entire pre-drive check lasts at least four seconds.

• All the indicator lamps are deactivated together at the end of a fault-free pre-drive check.
  
• If faults occur during the pre-drive check, the check is interrupted for the relevant systems.
  
• The affected indicator lamps remain on and the Check Control issues the associated message.
  

Switch-on scenarios

Terminal R: After terminal R ON, the time and the outside temperature are indicated in the display area inside the speedometer. Only this display area is backlit.

Terminal 15: The pre-drive check is activated from terminal 15 ON.

• The program display of the automatic transmission is then shown in addition to the time and outside temperature.
  
• Existing Check Control messages are indicated instead of the overall distance/trip distance in the display area inside the revolution counter.
  
• The overall distance/trip distance is briefly indicated in the display area inside the revolution counter.
  
• The service information is indicated in the display area below the speedometer. The display then switches to indication of the previous information, e.g. fuel level and consumption.
  
• Existing Check Control messages are shown in the display area inside the revolution counter.
  
• Once the engine is running, the variable rpm early warning zone is shown inside the revolution counter as long as the engine speed threshold transmitted by the DME is below the fixed warning zone.
  
• The marking ring is only indicated in the speedometer if thresholds have been set for the vehicle speed controller and/or the LIMIT function has been activated.
  
• The display areas of the speedometer and the revolution counter are only backlit when one of the display functions is active. Both display areas remain dark when only the LIMIT display is active.
  

Redundant data storage

Data must be retained when the instrument cluster is replaced so that tampering can detected. For this purpose, the following data are stored redundantly (for a second time) in the CAS Car Access System:

• Vehicle identification number
  
• Total distance (kilometre reading)
  
• CBS scopes
  

These data are checked each time terminal 15 is switched on. If discrepancies are detected, an orange tampering dot lights up in the display area below the revolution counter. This occurs in the following situations:

• The vehicle identification numbers stored in the two control units are different.
  
• A vehicle identification number is not stored in one of the two control units (e.g. new part).
  
• The module for storing the total distance travelled in the instrument cluster is faulty and the kilometre reading is indicated as 999999.
  

Diagnosis

The instrument cluster is a diagnosis-compatible system. Diagnosis and reading out of the fault memory in the instrument cluster are possible with the MoDiC or DISplus. The instrument cluster also has test functions, which are read out in its display.

Self-diagnosis

For function monitoring and fault detection, the instrument cluster runs a self-diagnosis. Identified faults are stored if they have been detected three times as ”true”. New faults are not taken into consideration when the memory is full. Faults which no longer occur after 40x terminal 15 ON/OFF are automatically deleted when the memory is full. The fault memory can be read out with the diagnostic unit or in the instrument cluster display.

Test functions

The listed test functions can be displayed in the instrument cluster when the trip distance reset button is pressed. The indication appears in the left display area inside the speedometer with an orange backlighting.

CC Check Control

The Check Control is a message system that reports faults in the vehicle; it serves to display operating states and instructions.

• The message texts (max. 40 characters) contain clear instructions.
  
• In parallel with the Check Control messages, further information (max. 170 characters) concerning the current message can be called up or appear automatically in the on-board data menu of the Control Display.
  
• In addition to German, there are a further 10 languages in which the texts can be displayed.
  

Display locations

The Check Control messages are displayed at various locations by fixed and variable indicator lamps in the instrument cluster.

• Variable indicator lamps light up yellow or red below the gear display. The time and the outside temperature normally displayed at this location are overwritten as required by the Check Control.
  
• Check Control text messages are displayed below the revolution counter. Data from the on-board computer which are already located at this position when the message is output are overwritten.
  

Most of the Check Control messages have supplementary explanations and instructions available in the control display. These explanations and instructions can be called up via the on-board data menu or are automatically displayed in particularly serious situations.

Display characteristics

Check Control messages are usually announced by a gong. The output takes the form of

• a text message with a fixed and/or variable indicator lamp,
  
• the text being featured in the display area below the revolution counter and usually with an additional explanation in the control display or
  
• a non-text message with a fixed indicator lamp.
  

The message with the highest priority is displayed if

• several text messages are to be output simultaneously or if
  
• different non-text notifications want to light up the same indicator lamp.
  

In addition to the visual display, the Check Control alerts the driver with acoustic signals.

On-board computer

”Main” on-board computer

The ”main” on-board computer contains the part functions ”Displays” and ”Additional settings”.

Displays: The computer supplies from terminal R data for the following displays:

• Distance: The distance can be input via the controller into the computer. The distance value is then counted down by the computer or transmitted by the navigation system to the instrument cluster. In this case, the navigation system calculates down to ”0”. In both case, the instrument cluster continues counting the ”minus distance”.
  
• Range: The range is calculated from a mean consumption value and the tank content. Stationary periods while the engine is running and sudden changes in driving style are compensated in the calculation to the greatest possible extent.
  
• Arrival time: The arrival time is calculated from the distance, the time and a mean driving speed. The arrival time can only be calculated if the clock has been set and a distance has been manually input.
  
• Average fuel consumption: The average consumption is calculated using the data from the consumption and travel memory. The calculation always begins with a manual ”reset”. The display appears after the first travel impulse.
  
• Average speed: The average speed is calculated using the data from the travel memory and timer.
  A ”reset” of average consumption and speed is carried out via the controller directly in the menu of the on-board computer in the control display. A dialog window appears in the display screen when one of these displays is selected. Selective resetting is possible with the dialog window.
  Individual information from the on-board computer can be displayed in the instrument cluster.
  Display field below speedometer: This field can display distance and/or range; in addition tank content.
  Display field below revolution counter: This field can display: arrival time, average fuel consumption, average speed, total and trip distance or current consumption.
  When the car is started, the information that was selected last is always shown in the display areas of the instrument cluster.
  No function of the on-board computer can be displayed below the revolution counter while a Check Control message is being displayed. Such a display is only possible after a specified minimum display time has elapsed or after the message has been cancelled by button operation. A top-priority message cannot be removed.
  

Additional settings: The following additional functions can be controlled via the on-board computer and displayed in the control display:

• Clock: The date and time must be manually input via the controller in the control display. The time is calculated and displayed in the instrument cluster. The time is also indicated in the control display.
  The time cannot be overlaid in the instrument cluster. The time features together with the indicated outside temperature in the LCD display field below the gear display. The display appears provided it is not overwritten by a variable Check Control indicator lamp.
  
• Memo signal: If the MEMO function has been activated and a time is set, the instrument cluster triggers from terminal R ON an hour signal 15 seconds before each full hour has elapsed. The function can be activated and deactivated in the control display.
  
• Timer for independent heating and independent ventilation: The timers for independent heating and independent ventilation are set in the air conditioner menu of the Control Display.
  The functions ”independent heating ON”, ”independent ventilation ON” and ”automatic selection independent heating/independent ventilation” are possible - depending on the outside temperature.
  
• Code: A code can be entered from terminal R ON in the Settings menu of the control display which prevents the engine from being started by unauthorized persons.
  

Travel on-board computer

The trip computer serves to monitor individual stages, which can also be stopped or interrupted.

The trip computer is activated with the controller in the START selection field. The information of the trip computer is only displayed in the control display. The following are displayed:

• Start time and start date
  
• Driving time and distance travelled
  
• Average fuel consumption and average speed
  

When a journey is interrupted, from terminal 15 OFF further calculation of the average values is discontinued (provided START or STOP is activated) and only started again when the journey is resumed.

Limit: As of terminal R On, a speed limit can be entered in the on-board computer via the Controller and the Control Display. The entry can be made using the Controller or the speed currently being driven can be adopted. The area above the input speed is represented inside the speedometer scale by a bright circle segment. When the speed exceeds the input value, this is indicated by a gong and a Check Control message.

The warning when the input limit is exceeded can only be output in driving mode (terminal 15 ON and travel pulse telegram). The current speed limit and the associated activation status are stored in the instrument cluster also after terminal 15 OFF.

Stop watch: The stop watch function is ready for operation from terminal R. The stop watch is started and stopped with the controller via the selection fields in the control display.