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

MODEL 164.1 as of model year 2009 

MODEL 164.8, 251.0/1 as of model year 2009 

Function requirements, general 

• Terminal 15 ON

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

Display operating conditions, general 

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

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

• Function sequence for vehicle speed display 
• Function sequence for display of engine RPM (except model 164.195) 
• Display of coolant temperature function sequence 
• Display of fuel quantity function sequence 
• Display of travel distance function sequence 
• Function sequence for gear display and transmission mode display 
• Function sequence for power display (with model 164.195) 
• Function sequence for display of power flow in display of COMAND operating, display and controller unit (A40/3) (on model 164.195) 

Function sequence for vehicle speed display 

The vehicle speed is calculated on the basis of the wheel speeds.

The ESP control unit (N47-5) (except model 164.195) or the regenerative braking system control unit (N30/6) (on model 164.195) sends information about wheel speeds to the instrument cluster via engine compartment CAN (CAN C). The instrument cluster calculates the vehicle speed, compares it with the internally stored speedometer characteristic, and then actuates the electronic speedometer (A1p8) accordingly by way of a stepper motor.

Function sequence for display of engine RPM (except model 164.195) 

The CDI control unit (N3/9) (with diesel engine) or the ME-SFI control unit (N3/10) (with gasoline engine) sends information about engine RPM to the instrument cluster via engine compartment CAN. The instrument cluster receives the engine RPM and actuates the tachometer (A1p5) accordingly by means of a stepper motor.

Display of coolant temperature function sequence 

The CDI control unit (with diesel engine) or the ME-SFI control unit (with gasoline engine) sends information about coolant temperature to the instrument cluster via engine compartment CAN. The instrument cluster receives the value for the coolant temperature and displays it in the upper area of the multifunction display (A1p13).

The coolant temperature display is actuated by a correction characteristic curve. This correction characteristic defines the following four temperature ranges in which the coolant temperature is displayed as follows:

• T = 40 to 95°C: The actual coolant temperature is shown.
• T = 95 to 115°C: The coolant temperature display constantly shows a value of T = 95°C.
• T = 115 to 120°C: The gap in the displayed temperature to the actual coolant temperature is closed.
• T = 120 to 130°C (start of red warning range): The actual coolant temperature is displayed. At a coolant temperature of T > 130 °C an additional warning message is also issued at the multifunction display in the instrument cluster.

In the event of a defective engine and air conditioning electric suction fan with integrated control (M4/7) the actual coolant temperature is displayed, including in the T = 95 to 115°C range. In parallel with this a warning message is issued on the multifunction display.

If the instrument cluster does not receive a value or if it receives a faulty value for the coolant temperature, the minimum value of T = 40 °C is displayed.

Display of fuel quantity function sequence 

The fuel tank fill level is monitored by the fuel level sensor, left tank half (B4/1) and fuel level sensor, right tank half (B4/2).

The rear SAM control unit (N10/8) reads in the fuel level indicator signals directly and transmits information about fill level of fuel tank to the instrument cluster via interior CAN. The instrument cluster receives this information, evaluates them with the aid of a tank characteristic and actuates the fuel level and reserve indicator (A1p2) accordingly 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). If the tank reserve drops to approx. 50 %, then a fuel station symbol in the form of a gasoline pump is shown in the multifunction display.

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 0.

Display of travel distance function sequence 

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

The ESP control unit or the regenerative braking system control unit transmits information about wheel speeds to the instrument cluster via engine compartment CAN.

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 999, 999 km or miles. When the maximum counter reading is reached, the counter does not start over again at 0. Internal processing is generally accomplished in km and the figure converted to miles when displayed.

The trip distance is displayed in the multifunction display of the instrument cluster. The maximum displayed counter reading for the trip distance is 9999, 9 km or miles. When the maximum counter reading is reached the overflow returns to 0. The counter reading for the trip distance can be manually reset by pressing the trip odometer reset button (A1s3) for t > 2 s.

The total distance is always 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 battery (G1) is disconnected. The current reading of the trip odometer is likewise stored in the nonvolatile memory of the instrument cluster.

Function sequence for gear display and transmission mode display 

Except model 164.195: 

The current gear and the current transmission mode are shown in the multifunction display.

The fully integrated transmission control unit (VGS) (Y3/8n4) transmits information about transmission mode to the instrument cluster via engine compartment CAN. The intelligent servo module for DIRECT SELECT (A80) transmits information on the engaged gear range to the instrument cluster via engine compartment CAN.

On model 164.195: 

The current gear and the current transmission mode are shown in the multifunction display.

The hybrid fully integrated transmission control controller unit (Y3/10) transmits information about the transmission mode to the instrument cluster via hybrid CAN (CAN L), ME-SFI control unit and engine compartment CAN. The intelligent servo module for DIRECT SELECT transmits information about the engaged gear range to the instrument cluster via engine compartment CAN.

The BlueHYBRID drive also has the transmission mode "E".

Function sequence for power display (with model 164.195) 

The instantaneously available output of the Blue hybrid drive is depicted on the energy display (A1p17) in the instrument cluster in percent.

The display relates to the maximum possible output and contains both the available electric drive output as well as that of the combustion engine. When braking, the momentary power reclaimed by regenerative braking is indicated by the power display.

The ME-SFI control unit internally processes the parameters for the engine control, in addition it reads in the parameters for the high-voltage battery mode (A100) from the battery management system control unit (A100n1) via hybrid CAN and the prognosis for the available torque from the power electronics control unit (N129/1) via drive train CAN (CAN C1) and transmits the data on power display to the instrument cluster via engine compartment CAN. The instrument cluster calculates the display values.

A separate depiction of the combustion engine output or the electric drive output is not possible.

When the ignition is switched off, the indicator on the power display is located at the left end stop (parallel to the electronic speedometer).

Function sequence for display of power flow in display of COMAND operating, display and controller unit (with model 164.195) 

The energy flow is indicated graphically in the display on the COMAND operating, display and controller unit and the driver is informed of the energy flow and activity of the combustion engine and electric motor.

For this purpose the battery management system control unit transmits the corresponding data via the hybrid CAN to the ME-SFI control unit, which processes the data internally and transmits them together with the data from the engine control to the COMAND operating, display and controller unit via engine compartment CAN, central gateway control unit (N93) and interior CAN. The COMAND operating, display and controller unit processes the data internally and displays it in the integrated display.

Graphic display of the energy flow diagrams is described in the "Hybrid drive system energy flow diagram".

Electrical function schematic of instrument cluster, operating condition display	MODEL 164.1 (except 164.195) as of model year 2009 MODEL 164.8 as of model year 2009	PE54.30-P-2055-97MAA
	MODEL 164.195 as of model year 2009	PE54.30-P-2055-97MAB
	MODEL 251.0/1 as of model year 2009	PE54.30-P-2055-97RAA
Overview of system components, instrument cluster (IC) component description		GF54.30-P-9996GM