Displaying coolant temperature, function - GF54.30-P-3020PM
MODELS 203.0 /2 /7 as of 24.4.04
General
The coolant temperature gauge (A1p1) is located on the left of the instrument cluster (A1) and is designed as an analog display. The display is driven by a stepper motor.
Once the instrument cluster (A1) is activated the pointer of the coolant temperature gauge (A1p1) is actuated at coolant temperatures of > 40 °C. If the coolant temperature is < 40 °C, the pointer of the coolant temperature gauge (A1p1) is at the start of the scale.
Fault behavior
If the CAN-C signal is defective or the instrument cluster (A1) does not receive a coolant temperature signal, the pointer is moved back dampened to the start of the scale. In addition an erroneous bit is set in the fault memory of the instrument cluster (A1).
Networking:
- The coolant temperature sensor (B11/4) changes its resistance corresponding to coolant temperature. The sensor has a negative temperature coefficient (NTC) resistance, i.e. the resistance reduces as temperature increases.
- The resistance of the coolant temperature sensor (B11/4) is read by the ME control unit (N3/10) or CDI control unit (N3/9).
- The motor electronics control unit (N3/10) or CDI control unit (N3/9) converts the resistance values of the coolant temperature sensor (B11/4) into a temperature value and places this on the Controller Area Network bus class C (engine compartment) (CAN-C).
- The instrument cluster (A1) reads in this temperature value from the CAN-C. The coolant temperature is displayed via the coolant temperature gauge (A1p1) of the instrument cluster (A1).
Display range of coolant temperature gauge (A1p1):
- In the coolant temperature range < 40 °C no value is displayed in the coolant temperature gauge (A1p1).
- In the coolant temperature range of 40 °C to 95 °C the value measured is displayed in the coolant temperature gauge (A1p1)
- In the coolant temperature range of 96 °C to 116 °C a set value at the level of 95 °C is displayed in the coolant temperature gauge (A1p1) instead of the value measured. This prevents the driver being disturbed unnecessarily by a high coolant temperature but which is not critical for the vehicle, e.g. when the outside temperature is high.
- In the coolant range of 116 °C to 130 °C the value measured is displayed in the coolant temperature gauge (A1p1).
- In the coolant temperature range > 130 °C the pointer is moved to the final value on the scale and a warning is issued in the multifunction display (A1p13). A warning signal also sounds.
In the event of a defective engine and AC electric suction fan with integrated control (M4/7) temperatures between 96 °C and 116 °C are also displayed.
| Instrument cluster (IC), location/task | GF54.30-P-3039PM |