Instrument functions

In the case of the instrument functions, the following functions are available in different display areas:

Needle display area

• Speedometer
  
• Power display
  
• Coolant temperature
  
• Fuel gauge
  

Instrument displays

• Total distance and trip distance traveled
  
• On-board computer
  
• Check Control display
  

Warning and signal displays

• Variable indicator lamp
  
• Airbag control lamp
  
• Belt warning
  
• Check Engine
  
• Anti-lock Brake System
  
• General brake warning lamp
  
• Brake warning
  
• Dynamic Stability Control warning lamp
  
• Parking brake control lamp
  
• Turn signal indicator lamps
  
• High beam indicator lamp
  
• Low beam indicator lamp
  
• Rear fog lamp indicator lamp (country version)
  
• Brake warning light
  

Acoustic signals

• Acoustic transmitter (external)
  

On-board computer functions

• See functional descriptions: On-board computer functions and control panels
  

Brief description of components

CAS Car Access System

The CAS Car Access System contains the functions of the radio remote control, the ignition starter button, the terminal control and the immobilizer. It is also the gateway module between the data buses K-CAN SYSTEM and K-CAN PERIPHERALS.

ZGM (Central Gateway Module)

The ZGM central gateway module 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 is the data connection between the instrument cluster and the control modules in the chassis and suspension, drive and body sections. Information is exchanged by means of data telegrams.

MOST bus

The MOST bus is the data connection between the control modules in the communications section (navigation system, ASK audio system controller, SVS language processing system, CD control display). Information is exchanged by means of data telegrams.

LM Light Module

The LM light module controls and monitors the vehicle lights. Information is received and sent via the data bus K-CAN SYSTEM.

DM door module

The door modules register the signals of the switches and sensors installed in the doors and control the drives installed in the doors. Information is received and sent via the K-CAN PERIPHERALS data bus.

PM Power Module

The PM power module monitors the battery charge state and the closed-circuit current consumption of the car. In addition, the trunk lid lock is controlled via the power module. Information is received and sent via the K-CAN PERIPHERALS data bus.

SZL steering column switching center

The SZL steering column switching center registers the signals of the switches and sensors installed on the steering wheel and the steering column. It also controls all the components located on the steering wheel and the steering column. Information is received and sent via the data bus BYTEFLIGHT.

Instrument cluster

The instrument cluster is manufactured in several hardware versions for different markets and is installed as a single-part component with assorted displays in the instrument panel.

The instrument cluster accommodates the following displays:

• LC display: All displays and messages are shown in the LC display.
  
• Needle instruments: Vehicle speed, power, fuel tank and coolant temperature are indicated by needle instruments. 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 multicolored non-replaceable LEDs.

A built-in display heater ensures that the display can be easily read even at low temperatures. The display heater is activated at display temperatures < 10°C. The switch-on signal is sent when the driver's door is opened from the CAS via the K-CAN SYSTEM data bus to the instrument cluster.

A control module for converting the input and output signals and two computers are integrated in the instrument cluster.

• One computer is responsible for the display, lighting, on-board computer and Check Control functions.
  
• The other computer is responsible for activating the needle instruments and the permanently installed indicator and warning lamps.
  

The instrument cluster is connected by way of the K-CAN SYSTEM data bus and the MOST to the vehicle electrical system. Information/prompts to and from the instrument cluster are transmitted as data telegrams.

Information is fed over conventional lines from:

• Outside temperature sensor
  
• Washer fluid level sensor
  
• Coolant level sensor
  
• Fuel tank sensor
  

Main functions

Display areas of instrument cluster

• LC display area
  Display area below the coolantand fuel gauge
  BC on-board computer and CC Check Control displays: see functional descriptions: On-board computer functions and control panels
  Both BC and CC messages are displayed in this area. BC text messages are overwritten by CC 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, variable display and warning field
  This area serves as a variable display and warning field. Contents can be displayed here as text or graphics.
  

• CC Check Control warning symbols: Each CC text message in display area is assigned a symbol which shows up red or yellow in this area.
  
• 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 value calculated by the instrument cluster taking into account the coolant temperature and vehicle speed.
  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.
  The speed indication is derived from signal sampled at the left rear wheel sensor and directed to the DSC control module. The signal (distance signal) conditioned by the DSC control module is sent in the form of a telegram via the PT-CAN to the ZGM and on via the K-CAN SYSTEM to the instrument cluster.
  Needle instrument: power display
  The power display and the scale captioning are represented on the permanently arranged graduated dial.
  The needle is moved by a stepping motor.
  The power signal is sent by the DME via the PT-CAN to the ZGM and on via the K-CAN SYSTEM to the instrument cluster.
  Display area: Indicator and warning lamps
  The indicator and warning lights are arranged to the left below the pointer instruments. The symbols are backlit for display purposes by colored and multicolored 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 lamps, fog lamps (national versions)
    
  • OBD II Check Engine (MIL)
    
  This area also contains the indicator and warning lamps for:
  
  • DSC Dynamic Stability Control
    

Pre-drive check: The pre-drive check serves to check the internal functions of the instrument cluster and to monitor the alive signals of all the control modules which can issue a CC message.

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

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

The alive signals of all the control modules which can issue a CC message is checked during the pre-drive check.

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.

Lighting and dimming

Lighting: The display areas are backlit and the displays are illuminated by LEDs.

The display is only backlit when there is a display in that area. EXCEPTION: Set speed limit.

Dimming: The brightness of the LC display and all the indicator and warning lamps is adapted with the aid of a phototransistor to the relevant light conditions.

The contrast of the LC display is adjusted automatically as a function of the LCD temperature and the operating time.

The contrast voltage is adapted to the temperature by the electronics in the instrument cluster through the use of an NTC resistor in the LC display.

The brightness signal is calculated in the instrument cluster from the values of the phototransistor and the dimmer potentiometer (setting of dimmer control wheel). This brightness signal is made available via the K-CAN bus to the other control modules (”dimmer master” function).

To take into account time-dependent aging, the non-operating and operating time of the instrument cluster is recorded with a built-in timer. The contrast voltage is automatically adapted as a function of the increasing operating time (increasing aging).

Turn signal indicator acoustics

A speaker is integrated in the instrument cluster to issue an acoustic signal when a turn signal indicator is activated.

All other acoustic signals are generated by the Audio System Controller (ASK) and output through the car speakers.

Trip odometer reset button

The following functions can be executed with the trip odometer reset button in the instrument cluster:

Brief pressing functions: When the ignition is off, the following are displayed for eight seconds when the trip odometer reset button is pressed briefly:

• Trip distance
  
• Total distance
  

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

Long-term pressing functions: When the ignition is off, the following functions are triggered when the button is pressed for longer than two seconds:

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

Switch-on scenarios

Terminal 30: After the driver's door has been opened, the parking brake light comes on and the display heater is activated depending on the temperature when the parking brake is activated.

Trip distance and total distance are displayed when the trip odometer reset button is ”briefly pressed”.

Terminal R: After terminal R ON, the outside temperature is indicated in the display area. This display area is backlit.

Existing CC messages are shown in the display area.

Terminal 15: The pre-drive check is activated from terminal 15 ON. The program display of the automatic transmission is shown in addition to the outside temperature.

The BC information can be called up. See functional descriptions: On-board computer functions and control panels

The total distance/trip distance is briefly indicated in the display area. The service information is shown in the display area.

Existing CC messages are shown instead of the total distance/trip distance in the display area.

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 (kilometer reading)
  
• CBS scopes
  

These data are checked each time terminal 15 is switched on. If discrepancies are detected, manipulation point lights up in the display area. This occurs in the following situations:

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

Observe the following when replacing the instrument cluster:

Installing a new CAS:

• Order CAS specifically to vehicle with key number, vehicle identification number, standard equipment.
  
• The engine can be started after the new CAS has been encoded with DIS (engine control/CAS calibration).
  
• NOTE: If a used CAS control module is installed, it will not be possible to unlock the car and start the engine.
  

Installing a new instrument cluster

• The tampering dot is set after terminal 15 is switched on because the vehicle identification number is not yet encoded in the instrument cluster.
  
• Carry out encoding with the DIS and allocate the instrument cluster to the vehicle (entry of vehicle identification number in instrument cluster).
  
• Switch terminal 15 off and on. Once terminal 15 has been switched on again, the current km reading and the CBS data are transmitted from the CAS to the instrument cluster. The tampering dot is deleted.
  

Trial installation of a new instrument cluster

• Although the vehicle identification numbers in the instrument cluster and CAS are different or have not been entered in the instrument cluster, a bidirectional communication takes place between the instrument cluster and CAS.
  
• E.g. the km reading stored in the CAS is transmitted to the main memory of the odometer in the instrument cluster and indicated.
  
• In a test drive, the kilometers covered are counted in the odometer main memory and transmitted to the CAS every 10 km.
  
• If at least 24 hours have passed between deactivation and activation of terminal 15, a further calibration is performed regardless of the kilometers covered.
  
• The main memory loses the stored kilometer reading when the instrument cluster is removed after a test drive. The data are not stored and the instrument cluster is returned to its initial state.
  
• NOTE: With a used instrument cluster, the entered vehicle identification number can be overwritten up to a kilometer reading of 254 km. It is not possible to reset the permanently stored value.
  

Simultaneous replacement of CAS and instrument cluster

Avoid replacing two new components simultaneously as the current km reading and all the CBS data will be irrevocably lost.

If the simultaneous replacement of both control modules cannot be avoided, it is recommended to adhere to the following installation sequence:

Replacing instrument cluster:

• Encoding of vehicle identification number
  
• Terminal 15 OFF and ON (data transmission possible if necessary)
  

Replacing CAS:

• Encoding of vehicle identification number
  
• Terminal 15 OFF and ON
  

The tampering dot is deleted after terminal 15 is switched on again. Communication between instrument cluster and CAS for redundant data storage is now guaranteed.

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 DIS via the K-CAN SYSTEM data bus. The instrument cluster also has test functions, which can be read out in its display.

On-board diagnosis: The instrument cluster carries out on-board diagnosis in order to monitor function and identify faults. Identified faults are stored if they have been detected three times as ”true”. The fault memory can be read out with the DIS.

Test functions: The listed test functions can be displayed in the instrument cluster when the trip odometer reset button is pressed. The display appears in the display area.

Calling up test functions:

• With terminal R (radio setting) or terminal 15 ON, press the trip odometer reset button for longer than five seconds o r
  
• with terminal R switched off, press and hold down the trip odometer reset button and switch on terminal R.
  

Displaying test functions:

• Identification: 01
  
• System test: 02
  
• (not assigned): 03
  
• Consumption: 04
  

The test function number is increased each time the trip odometer reset button is briefly pressed.

A maximum of four test functions can be shown simultaneously.

Except for test functions 1 and 2, all test functions must be unlocked by means of test function 19.

Starting selected test function: Press trip odometer reset button for longer than two seconds.

Displaying selected test function: The selected test function is displayed inside the tachometer.

Terminating test function:

• Switch off terminal R (radio setting) o r
  
• Press trip odometer reset button for longer than six seconds.
  

NOTE: After completing the tests, lock the test functions in accordance with test function 19.

CC Check Control

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

• The message texts (max. 40 characters) contain clear instructions.
  
• In addition to German, there are a further 10 languages in which the texts can be displayed.
  

Display locations: The Check Control signals are displayed at several locations by fixed and variable indicator lamps in the instrument cluster.

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

Display behavior: 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 in the display unit
  
• a non-text message with a fixed indicator lamp.
  

If several text messages are poised to be output simultaneously or if one indicator lamp is to be activated simultaneously by various non-text messages, the message with the highest priority is displayed first.

In addition to the visual display, the Check Control alerts the driver with acoustic signals. Depending on the importance of the accompanying message, a gong or a double gong of differing volume and tone sounds. Depending on its cause, the acoustic warning is issued from the left or right front car speaker.

Operation: The Check Control messages can be called up with the BC button on the turn indicator/dipping stalk. This is possible by:

• scrolling through with brief button pressing o r
  

The display automatically reverts to its initial state (rendering dark or on-board computer) eight seconds after the last button operation.

It is not possible to render the display dark if the Check Control is showing a top-priority message (e.g. engine overheating) or the fuel gauge indicates low fuel.

Country-specific version

Various hardware versions of the instrument cluster are fitted.

Languages and units

The languages and units can be set using the Central Information Display.

Language encoding

Language encoding: Depending on the country coding of the CAS Car Access Systems, a language package is programd in the Control Display.

From the possible three languages, one language can be selected at the Central Information 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).

Safety function

Load deactivation

The display heater is cut in/out by the power module as a function of the system voltage.