Display Operating Conditions, Function - GF54.30-P-3041CE

MODEL 204.0/2 as of model year 2009 

MODEL 204.3 

MODEL 204.9 

Function requirements, general 

• Circuit 15 On

The electronic ignition lock control unit (N73) transmits the circuit status of circuit 15 via interior CAN (CAN B) to the instrument cluster (A1).

Display operating conditions, general 

The operating conditions display provides the driver with permanent information about the current operating conditions of the vehicle.

The "display operating conditions" function comprises the following subfunctions:

• Function sequence for vehicle speed display 
• Display of engine speed function sequence 
• Display of coolant temperature function sequence 
• Display of fuel quantity function sequence 
• Display of travel distance function sequence 
• Gear and transmission mode display function sequence (with transmission 722) 
• Function sequence for "ECO" display (on model 204.0/2 as of 1.6.10 with code (B03) ECO start/stop function, on model 204.9 as of 1.12.10 with code (B03) ECO start/stop function) 
• Function sequence for offroad displays (on model 204.9 with code (430) Offroad package) 
• Display of transport mode function sequence (as of 1.6.12) 

Function sequence for vehicle speed display 

The Electronic Stability Program control unit (N30/4) reads in the signals of the left front axle rpm sensor (L6/1), right front axle rpm sensor (L6/2), left rear axle rpm sensor (L6/3) and the right rear axle rpm sensor (L6/4) directly and sends them to the instrument cluster via chassis CAN (CAN E). The instrument cluster receives the signals for the rpm sensors, calculates the current vehicle speed and then actuates the speedometer (A1p8) to match by means of a stepper motor.

Display of engine speed function sequence 

The engine rpm is detected by the crankshaft position sensor (L5) (with engine 271.9, 646, 651 without code (B03) ECO start/stop function) or by the crankshaft Hall sensor (B70) (engine 156, 271.8, 272, 274, 276, 642, 651 with code (B03) ECO start/stop function). The CDI control unit (N3/9) (for diesel engine) or the ME-SFI [ME] control unit (N3/10) (for gasoline engine) imports the signals of the crankshaft position sensor or the crankshaft Hall sensor, calculates the engine speed based on this and then sends a corresponding value via the chassis CAN to the instrument cluster. The instrument cluster receives the value for the engine speed and actuates the tachometer (A1p5) accordingly by way of a stepper motor.

Display of coolant temperature function sequence 

The coolant temperature is recorded by the coolant temperature sensor (B11/4). The CDI control unit or ME-SFI ME] control unit directly reads in the signal of the coolant temperature sensor, uses this to calculate the coolant temperature and sends the corresponding value via chassis CAN to the instrument cluster. The instrument cluster receives the value for the coolant temperature and actuates the coolant temperature display (A1p1) accordingly by way of a stepper motor.

The coolant temperature gauge is actuated via a correction characteristic. This correction characteristic defines the following four temperature ranges in which the coolant temperature display is actuated in different ways:

T = 0 to 80 °C:

The actual coolant temperature is displayed. The display is only shown as from T ≥ 40 °C.

T = 80 to 115 °C:

The coolant temperature display pointer constantly shows up to a value of T = 90 °C.

T = 115 to 120 °C:

The coolant temperature display pointer constantly shows up to a value of T = 95 °C.

T = 120 to 130 °C (Start of red warning range)

The actual coolant temperature is displayed. For coolant temperatures of T > 130 °C the coolant temperature warning lamp (A1e54) is also actuated and a warning message issued on the travel distance display (A1p7) (model 204.0/2/3/9 (except 204.077/277/377) without code (442) Comfort multifunction steering wheel) or the multifunction display (A1p13) (with code (442) Comfort multifunction steering wheel, model 204.077/277/377).

If a faulty combustion engine and air conditioning fan motor with integrated control (M4/7) is detected, the actual coolant temperature is displayed. The coolant temperature warning lamp is also actuated. If the instrument cluster does not receive any value for the coolant temperature, it actuates the coolant temperature warning lamp. The coolant temperature display is not actuated.

Display of fuel quantity function sequence 

The fill level of the fuel tank is detected by the left fuel level indicator sensor (B4/1) and right fuel level indicator sensor (B4/2). The rear SAM control unit with fuse and relay module (N10/2) reads in the signals from the fuel level indicator sensor directly and sends them via the interior CAN to the instrument cluster. The instrument cluster receives the signals for the fuel level indicator sensor, calculates them and then actuates the fuel level indicator (A1p2) to match by means of a stepper motor.

If the reserve range has been reached (approx. 12.5 % of maximum tank capacity), the instrument cluster actuates the fuel reserve warning lamp (A1e4). A corresponding message is also shown on the travel distance display or the multifunction display. The reserve range is defined by comparing the measured fill level against a stored tank characteristic. If the reserve range drops to approx. 50 %, a gas station symbol in the form of a gasoline pump is shown in the Range menu instead of the distance reading.

Display characteristics of fuel level indicator:

• After switching on circuit 15, the current fill level is displayed. In the process the pointer runs up in a buffered manner.
• After an engine start the display value for t = 4 s is updated every t = 0.8 s, to maintain a value below the full on-board electrical system voltage. After this time, or as soon as the vehicle starts off, the display is updated with a delay.
• When circuit 15 is switched off, the pointer gradually moves back to zero.

Possible jamming of the fuel level indicator sensor is detected by comparing the change in fill level of the fuel tank with the calculated composite mileage. If the fill level over a specific distance drops faster that is technically feasible with the composite mileage, the fuel level indicator sensor is deemed to be faulty and a corresponding message issued on the travel distance display or the multifunction display.

Display of travel distance function sequence 

The instrument cluster calculates the travel distance from the signals received from the rpm sensors taking the tire circumference into consideration. The Electronic Stability Program control unit reads in the signals of the left front axle rpm sensor, right front axle rpm sensor, left rear axle rpm sensor and the right rear axle rpm sensor directly and sends them to the instrument cluster via the chassis CAN.

The total distance is shown on the travel distance display or the multifunction display. The maximum displayed counter reading of the main odometer reading is 999,999 km or miles. This is followed by an overflow to 0. The actual kilometer reading however continues to be counted internally in the instrument cluster.

The trip distance is shown on the travel distance display or the multifunction display. The maximum displayed counter reading for the trip distance is 9999,9 km or miles. The display then overflows to 0.

Pressing the OK button (S110s6) in the left multifunction steering wheel button group (S110) enables the counter reading for the trip distance to be manually reset to 0.

If the unit for the trip distance is changed at a value that lies between 6213.7 and 9999.9 (e.g. from km to miles), the trip odometer is automatically reset to 0. This reset cannot be revoked when the unit is changed again.

The main odometer reading is saved continuously to the nonvolatile part of the instrument cluster's internal memory. This memory guarantees the retention of the counter reading for at least five years even when the on-board electrical system battery (G1) is disconnected.

The current reading of the trip odometer is likewise stored in the nonvolatile memory of the instrument cluster.

Gear and transmission mode display function sequence (with transmission 722) 

Gear indicator:

The data required for gear display is sent by the electronic selector lever module control unit (N15/5) via the drive train CAN (CAN C). The CDI control unit or ME-SFI [ME] control unit forward the data to the instrument cluster over the chassis CAN. The IC receives all the relevant information and issues this via the gear indicator (A1p12) (model 204.0/2/3/9 (except 204.077/277/377) without code (442) Comfort multifunction steering wheel) or the multifunction display (with code (442) Comfort multifunction steering wheel, model 204.077/277/377).

Transmission mode display:

The information for the transmission mode display on vehicles with transmission 722.6 is sent by the electronic transmission-control control unit (N15/3) to the drive train CAN. On model 204 (except model 204.077/277/377 with transmission 722.930) with transmission 722.9, this is done by the fully integrated transmission control unit (Y3/8n4). The CDI control unit or ME-SFI control unit forwards the information to the instrument cluster via the chassis CAN. On model 204.077/277/377 with transmission 722.930, the transmission mode control unit (N145) sends the corresponding information to the instrument cluster via chassis CAN.

Function sequence for "ECO" display (on model 204.0/2 as of 1.6.10 with code (B03) ECO start/stop function, on model 204.9 as of 1.12.10 with code (B03) ECO start/stop function) 

The automatic engine start/stop is automatically activated following each change of ignition, and it can be activated or deactivated by pressing the ECO start/stop function button (N72/1s50) in the UCP control unit (N72/1). The status of the button for the ECO start/stop function is read in by the upper control panel control unit and sent to front SAM control unit with fuse and relay module (N10/1) via the instrument panel LIN (LIN 1). The front SAM control unit sends the status via the chassis CAN to the ME-SFI control unit or the CDI control unit. When the function requirements are met the readiness for operation of the engine start/stop-automatic is shown to the driver by the "ECO" symbol in the travel distance display or in the multifunction display of the instrument cluster. The request for this is sent by the CDI control unit or by the ME-SFI control unit via the chassis CAN to the instrument cluster.

On transmission 722: If in driving mode the CDI control unit or ME-SFI control unit determines on the basis of the given parameters that the engine can be stopped automatically but neutral has not been engaged, the gearshift recommendation "→N" is shown in the travel distance display or on the multifunction display.

Function sequence for offroad displays (on model 204.9 with code (430) Offroad package) 

Various off-road functions can be switched on and off. The current status for these functions is shown in the travel distance display or in the multifunction display. The information necessary for this is sent by the front SAM control unit via the interior CAN. The corresponding status of the off-road program button (N72/1s25) or Downhill Speed Regulation button (N72/1s24) is read in by the front SAM control unit via the instrument panel LIN.

Display of transport mode function sequence (as of 1.6.12) 

Transport mode is activated at the factory at the end of the product process and sets the entire vehicle to a defined special state (e.g. limited vehicle speed or restricted outside lamp functions). The transport mode remains active on its way from the production plant to the dealers and company-owned sales and service outlets around the world up to the so-called delivery inspection and the final handover to the end customers. In active transport mode, a message and the remaining service time of the on-board electrical system battery in days is shown on the travel distance indicator or in the multifunction display.

Detailed information on the operating state of the transport mode is given in the separate function description for energy management.

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