Display operating conditions, function - GF54.30-P-3041CA

MODEL 207.3/4 

Function requirements, general 

• Terminal 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:

• Display of speed function sequence 
• Display of engine speed function sequence 
• Display of coolant temperature function sequence 
• Display of travel distance function sequence 
• Display of fuel quantity function sequence 
• Function sequence for gear and transmission mode display (with transmission 722, 725) 
• Function sequence for "ECO" display (with CODE B03 (ECO start/stop function)) 
• Function sequence for transport mode display (as of 01.06.2012) 

Display of speed function sequence 

The vehicle speed is calculated on the basis of the wheel speeds. The wheel speeds are recorded by the left front axle RPM sensor (L6/1), right front axle RPM sensor (L6/2), left rear axle RPM sensor (L6/3) and right rear axle RPM sensor (L6/4).

The Electronic Stability Program control unit (N30/4) (up to 31.05.2013 without CODE 233 (DISTRONIC PLUS) or as of 01.06.2013) or the Premium Electronic Stability Program control unit (N30/7) (up to 31.05.2013 with CODE 233 (DISTRONIC PLUS) reads in the signals from the RPM sensors and sends them up to 31.05.2013 via the chassis CAN (CAN E) to the instrument cluster or as of 01.06.2013 via chassis CAN 1 (CAN E1), the front SAM control unit with fuse and relay module (N10/1) and chassis CAN 2 (CAN E2) to the instrument cluster. The instrument cluster calculates the current vehicle speed, compares it against an internally stored speedometer characteristic, and then actuates the speedometer (A1p8) to match by way of a stepper motor.

Display of engine speed function sequence 

The engine speed is detected by the crankshaft position sensor (L5) (engine 651 without code B03 (ECO start/stop function)) or by the crankshaft Hall sensor (B70) (engine 271, 272, 273, 274, 276, 278, 642, engine 651 with CODE B03 (ECO start/stop function)). The CDI control unit (N3/9) (with diesel engine) or the ME-SFI control unit (N3/10) (with gasoline engine) reads in the signals from the crankshaft position sensor or the crankshaft Hall sensor, uses these signals to calculate the engine speed and sends the corresponding value up to 31.05.2013 via the chassis CAN to the instrument cluster or as of 01.06.2013 via chassis CAN 1, the front SAM control unit and chassis CAN 2 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 the ME-SFI control unit reads in the signal from the coolant temperature sensor directly, uses the signal to calculate the coolant temperature and sends the corresponding value up to 31.05.2013 via the chassis CAN to the instrument cluster or as of 01.06.2013 via chassis CAN 1, the front SAM control unit and chassis CAN 2 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 is displayed depending on the correction characteristic stored in the instrument cluster. This defines the following four temperature ranges:

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 gauge constantly shows a value T = 90_°C.

T = 115 to 120 °C:

The coolant temperature gauge constantly shows a value T = 95_°C.

T = 120 to 130 °C (start of red warning zone):

The actual coolant temperature is displayed.

When a coolant temperature of T > 130 °C is reached, the coolant temperature warning lamp (A1e54) is also permanently actuated and a warning message is issued via the multifunction display (A1p13).

When a faulty combustion engine and air conditioning fan motor with integrated control (M4/7) is detected, the actual coolant temperature is displayed in the coolant temperature gauge. 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 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 tire size is coded via the diagnostics tester.

The total distance display is shown in the multifunction display. The maximum displayed counter reading of the main odometer reading is 999.999. The display then overflows to 0. However, the actual kilometer reading continues to be stored internally in the instrument cluster.

The trip distance is shown in the multifunction display. The maximum displayed counter reading of the trip distance is 9999.9. If this value is reached, the counter returns to 0.

The main odometer reading is saved continuously to the nonvolatile part of the instrument cluster's internal memory. The current reading of the trip distance is likewise stored in the nonvolatile memory of the instrument cluster.

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.

Display of fuel quantity function sequence 

The fill level of the fuel tank is recorded 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 fuel level indicator sensor signals and sends them via 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 shown on 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 fuel level indicator pointer moves gradually back to zero.

A firmly attached fuel level sensor is detected by comparing any change in the fill level of the fuel tank with the calculated composite mileage. If the fill level drops faster over a specific distance than is technically feasible based on the composite mileage, the fuel level indicator sensor is deemed to be defective and a corresponding message issued on the multifunction display.

Function sequence for gear and transmission mode display (with transmission 722, 725) 

Gear indicator:

On vehicles up to 31.05.2013, the electronic selector lever module control unit (N15/5) sends the data required to display the gear 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 instrument cluster receives all the relevant information and then shows it on the multifunction display.

Transmission mode display:

On vehicles up to 31.05.2013 with transmission 722.6, the information required for displaying the transmission mode is sent by the electronic transmission control unit (N15/3) via the drive train CAN. With transmission 722.9, 725, this is done by the fully integrated transmission control unit (Y3/8n4). Up to 31.05.2013, the CDI control unit or the ME-SFI control unit sends the information to the instrument cluster via the chassis CAN. On vehicles as of 01.06.2013, the CDI control unit or the ME-SFI control unit sends the data via chassis CAN 1, the front SAM control unit and chassis CAN 2 to the instrument cluster. The instrument cluster receives all the relevant information and then shows it on the multifunction display.

Function sequence for "ECO" display (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 ECO start/stop function button is read in by the upper control panel control unit and sent via instrument panel LIN (LIN 1) to the front SAM control unit.

The front SAM control unit sends the status to the ME-SFI control unit or CDI control unit via the chassis CAN up to 31.05.2013 or via chassis CAN 1 as of 01.06.2013. If the function requirements are fulfilled, the driver is notified of the automatic engine start/stop readiness by the "ECO" symbol in the instrument cluster's multifunction display. The request for this is sent by the ME-SFI control unit or CDI control unit to the instrument cluster via the chassis CAN up to 31.05.2013 or to the instrument cluster via chassis CAN 1, the front SAM control unit and chassis CAN 2 as of 01.06.2013.

If the ME-SFI [ME] control unit or CDI control unit establishes in driving mode by means of the currently applied parameters that it is possible for the engine to stop automatically but neutral was not engaged, the gearshift recommendation "→ N" is output in the multifunction display.

Function sequence for transport mode display (as of 01.06.2012) 

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, the message "Transport mode" and the charge condition of the on-board electrical system battery are shown in the multifunction display in the form of a bar graph with 40 stages.

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

	Electrical function schematic of instrument cluster, operating condition display	MODEL 207.3/4 up to model year 2014	PE54.30-P-2055-97EAA
		MODEL 207.3/4 as of model year 2014	PE54.30-P-2055-97EAB
	Overview of system components, instrument cluster (IC) component description		GF54.30-P-9996CA