Displaying coolant temperature, function - GF54.30-P-3020S

Model 215, 220 

Networking of components 

Fig 1: Networking Of Components For Displaying Coolant Temperature

Signal flow, valid up to 31.8.02:

• The coolant temperature sensor (B11/4) changes its resistance according to the coolant temperature. (The sensor is an NTC resistor, i.e. its resistance decreases as the temperature rises.)
• The resistance of the coolant temperature sensor (B11/4) is read in by the motor electronics control unit (N3/9) or the CDI control unit (N3/10).
• The motor electronics control unit (N3/10) or the CDI control unit (N3/9) converts the resistance values of the coolant temperature sensor (B11/4) into a temperature value.
• This temperature value is transferred by the motor electronics control unit (N3/10) or CDI control unit (N3/9) to the engine compartment CAN.
• The instrument cluster (A1) reads in this temperature from the engine compartment CAN and actuates the coolant temperature gauge (A1p1) accordingly. If necessary, a warning message also appears on the multifunction display (A1p13).

  The coolant temperature gauge (A1p1) is driven by a step motor.

Display of coolant temperature:

• This display is a plateau display.

  That is to say, at temperatures between 95 °C and 115 °C the indicator remains at 95 °C. Temperatures within this temperature range are not critical. The correct temperature is only displayed once the temperature reaches 116 ° C. This avoids the driver being worried unnecessarily by the display, e.g. at high outside temperatures.

• The warning range begins at 128 °C. At temperatures in excess of 128 °C, the coolant temperature symbol and the warning message "COOLANT - STOP - ENGINE OFF!" is displayed in the multifunction display (A1p13). A warning signal also sounds.

If the engine fan fails, the plateau display disappears and the values between 95 °C and 115 °C are displayed.