GF54.30-P-3041RIT Display Operating Conditions, Function
GF54.30-P-3041RIT Display Operating Conditions, Function
- with CODE (P99) Special model "AMG Black Series"
General function requirements
^ Circuit 15 On
The status of circuit 15 is sent by the EIS [EZS] control unit (N73) to the interior CAN (CAN B).
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:
^ 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
^ Function sequence, gear display and transmission mode display
Additional function requirements for vehicle speed display
^ Vehicle speed v > 0 km/h
Function sequence for vehicle speed display
The vehicle speed is calculated on the basis of the wheel speeds. The wheel speeds are recorded by the following components:
- Left front rpm sensor (L6/1)
- Right front rpm sensor (L6/2)
- Left rear rpm sensor (L6/3)
- Right rear rpm sensor (L6/4)
The ESP, SPS [PML] and BAS control unit (N47-5) reads in the signals of the rpm sensors directly and forwards them over the engine compartment CAN (CAN C) to the instrument cluster (A1). The instrument cluster calculates the current vehicle speed, compares it against an internally stored speedometer characteristic, and then actuates the electronic speedometer (A1p8) to match by way of a stepper motor.
Comparison with the internally stored speedometer characteristic is performed to compensate for mechanical inaccuracies and meet the legal requirements with respect to displaying tolerances.
Additional function requirements for display of engine speed
^ Engine running (circuit 61 ON)
Display of engine speed function sequence
The engine speed is registered by the crankshaft position sensor (L5). The ME-SFI [ME] control unit (N3/10) reads in the crankshaft position sensor signals directly, uses them to calculate the engine speed and then sends a corresponding value over the engine compartment 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
Coolant temperatures are monitored by the coolant temperature sensor (B11/4). The ME-SFI [ME] 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 engine compartment 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.
If the coolant temperature value is missing or faulty, the pointer of the coolant temperature display is returned to the start of the dial (40 °C) and a fault filed in the instrument cluster's fault memory.
The coolant temperature display 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 96 °C:
The temperature displayed increases as the coolant temperature increases.
This is only displayed as of T = 40 °C.
- T = 96 °C to 116 °C:
The coolant temperature display pointer is held constantly at a value of T = 96 °C.
- T = 116 to 120 °C:
The temperature displayed increases as the coolant temperature increases.
- T = 120 °C to 130 °C (start of red warning range):
The actual temperature is displayed.
When a coolant temperature of T > 130 °C is reached, the instrument cluster actuates the coolant temperature warning lamp (A1e54) and issues a corresponding message on the left multifunction display (A1p13) and right multifunction display (A1p15).
If the engine and air conditioning electric suction fan with integrated control (M4/7) is recognized to be defective, the actual coolant temperature values are displayed.
Display of fuel quantity function sequence
The display of the fuel quantity consists of the following subfunctions:
^ Display of fuel quantity function sequence
^ Refueling detection function sequence with circuit 15 ON
Display of fuel quantity function sequence
The fill level in the fuel tank is recorded by the fuel level indicator sensor (B4). The rear SAM control unit (N10/8) reads in the data directly from the fuel level indicator sensor and sends the data over the interior CAN to the instrument cluster.
The instrument cluster receives the fuel level indicator sensor signals, evaluates them with the aid of a tank characteristic and then actuates the fuel level and reserve indicator (A1p2) to match through 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).
Once the reserve range has dropped to approx. 50 %, the instrument cluster also issues a corresponding message on the multifunction displays. The left multifunction display shows the fuel pump symbol instead of distance to empty and the right multifunction display displays "Fuel reserve".
Display characteristics of fuel level and reserve indicator:
- After switching on circuit 15, the current fill level is displayed. In the process the pointer runs up in a buffered manner.
- When circuit 15 is switched off, the pointer gradually moves back to zero.
Refueling detection function sequence with circuit 15 ON
"Refueling" is detected by comparison of the instantaneous display value with the fuel tank's measured fill level.
If the difference between the two values is greater than the defined value (3 liters with circuit 15 OFF, 7 liters with circuit 15 ON), then "refueling" is detected. After the ignition is switched off, the fuel content is measured again and stored. If circuit 15 is switched on again the display in the fuel level and reserve indicator is updated and the pointer are started-up.
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.
Display of main odometer reading function sequence
The main odometer reading display is shown in the left multifunction display. The maximum displayed counter reading of the main odometer reading is 999,999. The display then resets to 000,000. 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 right multifunction display. The maximum counter reading display for the trip distance is 9999.9. When this value is reached, an overflow takes it back to 0. In contrast to the total distance display, the trip odometer is faded out when another vehicle function is active.
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 battery (G1) is disconnected.
The current reading of the trip odometer is likewise stored in the nonvolatile memory of the instrument cluster. However the current counter reading is first transferred from the volatile memory to the nonvolatile memory after a circuit change from circuit 15 ON to circuit 15 OFF.
Function sequence, gear display and transmission mode display
The current gear is displayed to the left of the trip distance in the right multifunction display and the current transmission mode is displayed to the right. The data required for the gear and transmission mode display are sent by the electronic transmission control (EGS) control unit (N15/3) to the engine compartment CAN.
