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

Model 172.4 

Function requirements, general

• Circuit 15 ON

The electronic ignition lock control unit (N73) sends the circuit status of circuit 15 via the interior CAN (CAN B) as of 01.03.2016 and via the chassis CAN (CAN E) up to 29.02.2016 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 (transmission 722.9 up to 29.02.2016, 725.0)
• 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 Electronic Stability Program control unit (N30/4) transmits information about the wheel speeds to the instrument cluster via chassis CAN 1 (CAN E1), the front SAM control unit with fuse and relay module (N10/1) and chassis CAN 2 (CAN E2) as of 01.03.2016 and via the chassis CAN up to 29.02.2016. The instrument cluster calculates the current vehicle speed, compares it against an internally stored speedometer characteristic, and then actuates the speedometer (A1 p8) to match by way of a stepper motor.

Display of engine speed function sequence

The CDI control unit (N3/9) (diesel engine) or the ME-SFI control unit (N3/10) (gasoline engine) transmits information about the engine speed to the instrument cluster via chassis CAN 1, the front SAM control unit and chassis CAN 2 as of 01.03.2016 and via the chassis CAN up to 29.02.2016. The instrument cluster receives this and actuates the tachometer (A1p5) accordingly via a stepper motor.

Display of coolant temperature function sequence

The CDI control unit or the ME-SFI control unit transmits information about the coolant temperature to the instrument cluster via chassis CAN 1, the front SAM control unit and chassis CAN 2 as of 01.03.2016 and via the chassis CAN up to 29.02.2016. The instrument cluster receives this and actuates the coolant temperature gauge (A1p1) accordingly through 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 = 40 to 80°C:

The coolant temperature gauge shows the actual coolant temperature.

• 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 coolant temperature gauge shows the actual coolant temperature.

At coolant temperatures of T > 124°C, the instrument cluster also actuates the coolant temperature warning lamp (A1e54). A corresponding warning is shown in the multifunction display (A1p13) of the instrument cluster. 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.

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.

Display of travel distance function sequence

The instrument cluster calculates the traveled distance from the wheel speeds, taking the tire circumference into consideration.

The Electronic Stability Program control unit transmits information about the wheel speeds to the instrument cluster via chassis CAN 1, the front SAM control unit and chassis CAN 2 as of 01.03.2016 and via the chassis CAN up to 29.02.2016.

The tire size is coded via the diagnostics tester.

The total distance is displayed in the multifunction display of the instrument cluster. The maximum displayed counter reading of the main odometer reading is 9.999.999. This is followed by an overflow back to 0. The actual kilometer reading however continues to be counted internally in the instrument cluster. The trip distance is displayed in the multifunction display of the instrument cluster. The maximum displayed counter reading of the trip distance is 9999, 9. If this value is reached, an overflow back to 0 takes place.

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 distance is likewise stored in the nonvolatile memory of the instrument cluster.

Display of fuel quantity function sequence

Display characteristics of fuel level indicator:

The fuel level indicator sensor (B4) records the fill level of the fuel tank. The rear SAM control unit with fuse and relay module (N102) reads in the fuel level indicator sensor signals directly and forwards them over the interior CAN (CAN B) 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 (A1 p2) 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.

• 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 of the fuel level indicator is suppressed and moves back to 0

A fuel level indicator sensor which is jammed tight is detected by comparing the change in fill level of the fuel tank with the calculated composite mileage. If the fill level over a certain distance drops more quickly than technically feasible based on composite mileage, the fuel level indicator sensor is recognized as being defective and the corresponding message is shown in the multifunction display.

Function sequence for gear and transmission mode display (transmission 722.9 up to 29.02.2016, 725.0)

The information on the engaged gear is shown in the gear indicator

(A1p12).

Transmission mode information is shown in the transmission mode display (A1p16). Gear indicator:

As of 01.03.2016, the DIRECT SELECT INTERFACE (N150) (with transmission 725.0) transmits information about the engaged gear range via the drive train CAN (CAN C), the CDI control unit or the ME-SFI control unit, chassis CAN 1, the front SAM control unit and chassis CAN 2 to the instrument cluster. Up to 29.02.2016, the electronic selector lever module control unit (N15/5) (with transmission 722.9) or the DIRECT SELECT INTERFACE (N150) (with transmission 725.0) transmits information about the engaged gear range via the drive train CAN (CAN C), the CDI control unit or the ME-SFI control unit and the chassis CAN to the instrument cluster. The instrument cluster receives this and actuates the gear indicator accordingly. Transmission mode display:

The fully integrated transmission control unit (Y3/8n4) transmits information about the selected transmission mode to the instrument cluster via the drive train CAN, the CDI control unit or the ME-SFI control unit, chassis CAN 1, the front SAM control unit and chassis CAN 2 as of 01.03.2016. Up to 29.02.2016, the fully integrated transmission control unit transmits this information via the drive train CAN, the CDI control unit or the ME-SFI control unit and the chassis CAN to the instrument cluster. The instrument cluster receives this and actuates the transmission mode display accordingly.

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 upper control panel control unit directly reads in the status of the ECO start/stop function button and sends it via the instrument panel LIN (LIN 1), the front SAM control unit and via chassis CAN 1 as of 01.03.2016 or via the chassis CAN up to 29.02.2016 to the CDI control unit or the ME-SFI control unit. The CDI control unit or the ME-SFI control unit checks all the function requirements and sends the status of the automatic engine start/stop to the instrument cluster via chassis CAN 1, the front SAM control unit and chassis CAN 2 as of 01.03.2016 or via the chassis CAN up to 29.02.2016. The operational readiness of the automatic engine start/stop is displayed for the driver on the multifunction display of the instrument cluster with the symbol "ECO".

If, in driving mode, the CDI control unit or the ME-SFI [ME] control unit establishes by means of the currently applied parameters that automatic stopping of the engine is possible but neutral has not been engaged, the gearshift recommendation → N" appears 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 hand over to the end customers.

When transport mode is active, the message "Transport mode" and the charge level of the on-board electrical system battery are shown in the multifunction display of the instrument cluster in the form of a bar graph with 40 segments

Detailed information on transport mode is available in a separate document.

	Electrical function schematic for instrument cluster operation status display	Model 172.4 as of model year 2017	PE54.30-P-2055-97TAB
		Model 172.4 up to model year 2017	PE54.30-P-2055-97TAA
	Overview of system components, instrument cluster (IC) component description		GF54.30-P-9996RD