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

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

General function requirements
^ Circuit 15 On

The electronic ignition lock control unit (N73) provides the status of circuit 15 to the instrument cluster (A1) via the chassis CAN (CAN E).

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 is comprised of the following partial functions:
^ 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
^ Gear and transmission mode display function sequence (with transmission 722)
^ Function sequence for "ECO" display (with code (B03) ECO start/stop function)

Additional function requirements for display of speed
^ Vehicle speed v > 0 km/h

Display of speed function sequence
The vehicle speed is calculated on the basis of the wheel speeds. The wheel speeds are recorded by the following components:
- Left front axle rpm sensor (L6/1)
- Right front axle rpm sensor (L6/2)
- Left rear axle rpm sensor (L6/3)
- Right rear axle rpm sensor (L6/4)

The Electronic Stability Program control unit (N30/4) (without code (233) DISTRONIC PLUS) or the Premium Electronic Stability Program control unit (N30/7) (with code (233) DISTRONIC PLUS) reads in the signals of the rpm sensors and transmits these over the chassis CAN 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.

Additional function requirements for display of engine speed
^ Circuit 61 ON

Display of engine speed function sequence
The engine rpm is recorded by the crankshaft position sensor (L5) (with engine 651) or by the crankshaft Hall sensor (B70) (with engine 156, 271, 272, 273, 642). The CDI control unit (N3/9) (for diesel engine) or the ME-SFI [ME] control unit (N3/10) (for gasoline engine) reads in the signals of the crankshaft position sensor or the crankshaft Hall sensor, calculates the engine speed and then sends a corresponding value over 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 reads in the signal of the coolant temperature sensor, uses it to calculate the coolant temperature and then sends the corresponding value over the 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 shown. This is only displayed as of T ≥40 °C.
- T = 80 °C to 115 °C:
The coolant temperature display pointer is actuated constantly to a value of T = 90 °C.
- T = 115 °C to 120 °C:
The coolant temperature display pointer is actuated constantly to a value of T = 95 °C.
- T = 120 to 130 °C (start of red warning range)
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 fan motor and air conditioning with integrated closed-loop control (M4/7) is detected the actual coolant temperature in the coolant temperature gauge 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 travel distance function sequence
The travel distance display function is made up of the following subfunctions:
^ Determination of travel distance function sequence
^ Display of main odometer reading function sequence
^ Display of trip distance function sequence
^ Storage of counter readings function sequence

Determination 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 can be coded with the diagnostic tester.

Display of main odometer reading function sequence
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.

Display of trip distance function sequence
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 figure returns to 0.

Storage of counter readings function sequence
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 batte (G1) is disconnected.

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

Display of fuel quantity function sequence
The 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 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 (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 of the fuel level indicator is suppressed and moves 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, gear display and transmission mode display
The gear and transmission mode display is realized on the multifunction display in the instrument cluster.
Gear indicator:
The information for the gear indicator on vehicles with transmission 722.6 is sent by the electronic selector lever module control unit (N15/5) to the drive train CAN (CAN C). For vehicles with transmission 722.9 this is done by the intelligent servo module for DIRECT SELECT (A80).

The CDI control unit or ME-SFI [ME] control unit forwards this information to the instrument cluster via the chassis CAN.

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 212 except model 212.077/277 with transmission 722.9, this is done by the fully integrated transmission control unit (Y3/8n4). The CDI control unit or ME-SFI [ME] control unit forwards this information to the instrument cluster via the chassis CAN. On model 212.077/277 the transmission mode control unit (N145) sends the corresponding information over the chassis CAN to the instrument cluster.

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 UCP control unit, and forwarded over the instrument panel LIN (LIN 1) to the front SAM control unit. The front SAM control unit sends the status over the chassis CAN to the ME-SFI [ME] control unit.

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 [ME] control unit over the chassis CAN to the instrument cluster.

If the ME-SFI [ME] control unit uses the given parameters, when driving, to determine that the engine can be automatically stopped, although neutral has not been engaged, the gearshift recommendation "-->N" is shown on the multifunction display.