Instrument Functions Part 1

Instrument Functions

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

Needle display area
- Instrument cluster supply
- Speedometer
- Rev counter
- Dimming, needle area
- Display heater
- Stages, cruise control
- Active cruise control

Instrument displays
- Fuel gauge
- Total distance and trip distance traveled
- Dimming, display area
- Fuel consumption (economy) display
- Clock
- Outside temperature
- Navigation display
- Check Control display
- ACC Adaptive Cruise Control display
- Display heater
- Transmission program display

Warning and signal displays
- Variable indicator lamp
- Airbag indicator lamp
- Belt warning
- Check Engine
- Anti-lock braking system
- General brake warning lamp
- Brake warning
- Dynamic Stability Control warning lamp
- Parking brake control
- Turn signal indicator lamps
- High beam indicator lamp
- Low beam indicator lamp
- Front fog lamp indicator lamp
- Rear fog light indicator lamp
- Brake warning light

Acoustic signals
- Acoustic transmitter (external)

On-board computer functions
- On-board computer display
- On-board computer button, left and right

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 K-CAN SYSTEM and K-CAN PERIPHERALS data buses.

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 with 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 with data telegrams.

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

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 data bus K-CAN PERIPHERY.

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 data bus K-CAN PERIPHERY.

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.

Controller
The controller is the operating unit for the on-board computer. It is fitted at the front in the center armrest.

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 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 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 degrees 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 for the display, lighting, on-board computer and Check Control functions.
- The other computer is 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

Display area 1: LC display

Display area 1, inside the speedometer
Contents can be displayed in this area as text and graphics:
- Speed limit: To avoid overspeeding (e.g. when winter tires are fitted), it is possible to set a speed limit via the on-board computer.

The set limit is indicated by a bright circle segment, which begins at the limit and stretches round to the end of the scale. An acoustic signal sounds if this limit is exceeded.

- Vehicle speed controller: The vehicle speed controller can be used to store and call up to six speed markers as round markings. Values often required, such as e.g. 50 km/h, 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.

- Diagnostic test function: A total of 21 test functions can be selected in the display area inside the speedometer with the trip odometer reset button in the top left corner of the instrument cluster. The content of the test function selected is shown in the display area inside the rev counter.

- CBS Condition Based Service reset: The CBS restet functions can be selected in the display area inside the speedometer with the trip odometer reset button in the top left corner of the instrument cluster. The content of the function selected is shown in the display area inside the rev counter.

Display area 2, inside the rev counter
Contents can be displayed in this area as text and graphics:
- 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.

Until before the next turnoff point, the distance to this point is indicated numerically. Thereafter the distance is indicated with a bar graphic. The bar decreases continuously until the car turns off.

The navigation system determines whether the distance to the next turnoff point is indicated numerically or graphically.

The data are transmitted from the navigation system in the form of a telegram via the MOST bus to the instrument cluster.

Display area 3, below the speedometer
Contents can be displayed in this area as text and graphics:
- 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/dipping lever, it is possible to switch between the BC displays.

Display area 4, below the rev counter
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 5).

Display area 5, 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 4 is assigned a symbol which shows up red or yellow in this area.

If there are no incoming CC messages, the outside temperature and time are permanently displayed.

- Outside temperature: The display resolution is 0.5 degrees C. If the temperature drops below +3 degrees 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.

- Time: The quartz clock integrated in the instrument cluster can be manually set by means of the controller in the control display.

In cars fitted with navigation systems, the time, once it has been manually set, is corrected in the minutes range on the basis of the UTC (United Time Coordinated) world time received by the navigation system.

Because only the deviation of the minutes 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.

The instrument cluster is the time master for all the other control modules. The time information is made available to the other control modules as a telegram via the K-CAN SYSTEM data bus.

Time and outside temperature are displayed from terminal R ON.

Display area 6, gear indicator
In Steptronic mode, the gear selected by the transmission (M1 to M6) is displayed in this area.

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.

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.

Display area 3, needle instrument: Rev counter
The rev 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 engine speed 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 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 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 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) and
- 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 module.

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

Predrive check:The predrive 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 predrive check lasts at least four seconds.

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

All the indicator lamps are deactivated together at the end of a fault-free predrive check.

If faults occur during the predrive check, the check is interrupted for the relevant systems.

The affected indicator lamps remain on and the Check Control issues the associated message.

Illumination and dimming
Illumination:The display areas are backlit and the needles and graduated dials illuminated by LEDs in BMW orange.

The individual display areas are only backlit when information is actually being indicated there. EXCEPTION: Set speed limit. Two adjacent display areas are always backlit simultaneously.

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".

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. The acoustic signals are generated by an integrated sound generator.

All other acoustic signals are generated by the ASK audio system controller and output through the car speakers.

Trip odometer reset button
The following functions can be executed with the trip odometer reset button in the top left corner of 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
- Time
- Outside temperature

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.
- The SBA service indicator is reset.

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, time and outside temperature are displayed when the trip odometer reset button is "briefly pressed". Only the display areas inside the speedometer and the rev counter are backlit.

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.

Existing CC messages are indicted in the display area inside the rev counter.

Terminal 15: The predrive 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.

The BC information can also be called up by means of the buttons on the turn indicator/dipping lever.

The overall distance/trip distance is briefly indicated in the display area inside the rev 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 CC messages are indicated instead of the overall distance/trip distance in the display area inside the rev counter.

Once the engine is running, the variable rpm early warning zone is indicated in the display area inside the rev 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 rev 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 (kilometer 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 rev counter. 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 MoDiC or DISplus (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 MoDiC or DISplus 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 bi-directional communication takes place between the instrument cluster and CAS.
- For example, 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.