Instrument Panel, Gauges and Warning Indicators: Description and Operation

Instrument Panel

Instrument panel
New technology is used for the instrument cluster: Black Panel. This is a panel coated on the rear side with a black film. The Black Panel covers the entire area of the instrument cluster (high version). The remaining area is designed in such a way that the symbols of the indicator lights are not visible when switched off. (Basic version). The two large accentuation rings for the speed reading and engine speed display are galvanized. The two small dial areas for the fuel gauge and engine oil temperature are also galvanized. When switched off, the active areas of the displays are not visible.















NOTE: Additional fixed indicator lights.

In the basic version, there is additionally the indicator light LIM. This indicator light illuminates for pending information about Speed Limit Info (road sign recognition).
The instrument cluster starts up gradually.
At the request of the transmission control unit, the engaged gear is displayed in the instrument cluster.







The high version of the instrument cluster is described in the following text.

Brief component description
The following components are described for the instrument cluster:

TFT display
In the instrument cluster, a horizontal 960 x 160 pixel TFT display is integrated under the round instrument. The large analogue round instruments are open in a downward direction. These round instruments are closed by graphics of the display.







Outside temperature sensor
The outside temperature sensor supplies the value for the temperature outside the car to the instrument cluster. The ambient temperature is shown on the liquid crystal display. Instrument resolution is 0.5 °C (1 °F) . The value for ambient temperature is also made available to other control units via the K-CAN. The signal from the outside temperature sensor is digitalized in the instrument panel. A calculation model suppresses the effects of thermal radiation from the engine compartment on the signal. At higher driving speeds and lower engine temperatures the system selects lower suppression rates. The true ambient temperature can only be reliably expected starting at roadspeeds of about 80 km/h.

JBE: Junction Box Electronics
The fuse and relay module within the Junction Box Electronics module provides the instrument cluster with the connection to Terminal 30F and Terminal 30B. In addition, the junction box electronics (JBE) provide the instrument cluster with various other required signals on the bus system (K-CAN2 -> central gateway module ZGM -> PT-CAN).







Fuel level sensor
The fuel tank contains two fuel level sensors. Each fuel level sensor sends a signal indicating the amount of fuel in the tank. A value is obtained by adding the two signals. The fuel level sensors are connected to the Junction Box Electronics (JBE). The signal is transmitted to the instrument cluster on the K-CAN2.

NOTE: Follow the repair instruction.

The left-hand fuel level sensor cannot be replaced separately.

Coolant level switch
The coolant level switch sends a signal if the coolant level is too low (Reed contact). The information appears in the TFT display in the form of a Check Control message. The coolant level switch is connected to the Junction Box Electronics (JBE). The signal is transmitted to the instrument cluster on the K-CAN.

Washer fluid level switch
The washer fluid level switch sends a signal when the washer fluid level is too low. The information appears in the TFT display in the form of a Check Control message. The washer fluid level switch is connected to the Junction Box Electronics (JBE). The signal is transmitted to the instrument cluster on the K-CAN2.

Acoustic generator
The acoustic sensor in the instrument cluster (KOMBI) issues acoustic signals for the following functions:
- Turn indicators
- Hazard warning flashers
The volume varies as a function of vehicle speed.

On-board computer button
The on-board computer button is electrically connected to the steering-column switch cluster (SZL). The signal is forwarded on the FlexRay to the central gateway module (ZGM). The instrument cluster receives the signal from the central gateway module on the PT-CAN.







The on-board computer functions can be called up by briefly pressing the on-board computer button on the steering column stalk. Pressing the on-board computer button again displays the information in the following order:
- Remaining cruising range
- Average fuel consumption
- Average speed
- Distance (with route guidance activated)
- Estimated time of arrival (with route guidance activated)
- Date
- Road sign recognition

System functions
The following system functions are described for the instrument cluster:
- Operating readiness
- Operating voltage range
- Outside temperature interference suppression
- Brightness control
- Set speed for the cruise control
- Redundant data storage

Operating readiness
Operational status (operating readiness) depends on the terminal.
- Terminal 30B (basic operation) and Terminal 30F (fault)
The instrument cluster receives power from Terminal 30B and 30F via the junction box. The terminal status (Terminal R or Terminal 15) is made available to the instrument cluster via the bus system. With Terminal 30 (terminal R Off), the instrument cluster is in the standby mode. Pressing the reset button wakens the instrument cluster to display the following: Odometer, time display, ambient temperature, fuel level (can be encoded). The display goes out after 25 seconds.

- Terminal R
With terminal R On, the following are evaluated: Turn signal indicator/high beam switch and fuel level sensor. The time and ambient temperature appear in the TFT display. The on-board computer functions can be started using the on-board computer button (display unlimited in time). Terminal R is reached automatically once the engine has been stopped.

- Terminal 15
When terminal 15 is switched ON, a pre-drive-check is carried out on the permanent indicator and warning lights.

- Terminal 50 (starter motor)
During the engine start, the vehicle voltage can fall to such a degree that the internal voltage supply (6 Volts) can no longer be maintained. In this case, no analogue signals can be evaluated. No storage processes are run (in the EEPROM) either.

Operating voltage range
The operating voltage range is from 9 to 16 Volts. At a voltage below 7.5 Volts, undervoltage is detected. At a voltage above 16 Volts, no analogue inputs are evaluated.

Outside temperature interference suppression
The computation model in the instrument cluster compensates for effect that the residual heat from the engine compartment has on the ambient temperature signal. The increase in temperature is delayed. The input variables for the calculation model are:
- Driving speed
- Coolant temperature
- Status engine on/off
- Ambient temperature

A drop in the ambient temperature is adopted and not damped. The engine and the body cannot be colder than the ambient temperature.

NOTE: Under certain circumstances, an incorrect display of the ambient temperature is physically unavoidable.

Under certain driving conditions, the display deviates from the real value due to damping. In the event of a customer complaint, this behavior must be explained as the state of the art.
Example for outside temperature compensation:
Motorway driving followed by urban traffic, then stationary traffic







Brightness control
Due to the Black Panel technology, the instrument cluster is always illuminated as of terminal R. The status of the vehicle lights and the ambient brightness determine the switch between daytime and night-time illumination. A phototransistor is installed in the instrument cluster to calculate the necessary brightness (display, indicator and warning lights, scales, needles).
The brightness value calculated in the instrument panel is transmitted to the bus system (e.g., for the Central Information Display). Dimming can be set individually using the rheostat wheel on the light switch. When the vehicle lights are switched on, these individual settings and the phototransistor are used to control the dimming. When the vehicle lights are switched off, the dimming is only controlled by the phototransistor (display brightness according to ambient brightness).

Set speed of the cruise control
The set speed of the cruise control is transferred by the control unit for Integrated Chassis Management (ICM) on the bus system. Cruise control is activated via the steering column switch cluster (SZL). The set speed is transferred and displayed with a resolution of 1 kph. The set speed is indicated by a 2-colour marking (pointer):
- Green: Cruise control active
- Orange: Cruise control not active

Notes for Service department

General notes

Instrument cluster test functions
The test functions are displayed in the TFT display of the instrument cluster. The test functions are used in service to check the encoding. The test functions are also an aid to troubleshooting without the diagnosis system.
Starting the test functions
- Condition: Terminal R ON, vehicle stationary, engine switched off
- Hold down the reset button in the instrument cluster for 15 seconds
- Diagnosis system: Service functions -> Body -> Display and information functions -> instrument cluster system test

Locking and unlocking test functions (test function 19)
Only the first two test functions are freely accessible. As of the 3rd test function, all other test functions are locked. Unlocking is only possible using test function 19. The test functions are unlocked by entering the total of the vehicle identification number.
Terminating the test function
- Terminal change
- Press the reset button for longer than 5 seconds
- Test function 21 called

National market versions
The instrument cluster is available in various national-market versions.
Not responsible for printing errors, mistakes and technical changes.