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Home >> Mercedes Benz >> 2003 >> CLK500 >> Repair and Diagnosis >> External Pages >> Different car >> Section 324 (Electrical System, Equipment & Instructions -- CLK350 Coupe (209.356)) >> Basic Knowledge >> Displaying coolant temperature, function - GF54.30-P-3020Q

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

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Model 209.3 /4 

Fig 1: Coolant Temperature Display Function Diagram
G07718235Courtesy of MERCEDES-BENZ USA

Function overview 

The coolant temperature sensor (B11/4) is an NTC resistor which changes its resistance according to the coolant temperature. Its resistance drops and the temperature rises.

The resistance from the coolant temperature sensor (B11/4) is read in by the motor electronics control unit (N3/10) or the CDI control unit (N3/9) and passed as a CAN message on the engine compartment CAN.

The instrument cluster (A1) reads in this temperature from the engine compartment CAN and controls the engine coolant temperature gauge (A1p1) accordingly. If necessary, a warning message also appears on the multifunction display (A1p13).

Displaying the coolant temperature 

The status display for the engine coolant is located on the right-hand side of the instrument cluster (A1).

The display is a segment display.

After the instrument cluster (A1) has been woken, one segment is actuated at temperatures < 40°C; at higher temperatures the segments are actuated according to the values measured by the coolant temperature sensor (B11/4). The display is held at 95°C for input values from 95°C to 115°C.

IMPORTANT The system responds to a defective engine fan by leaving the characteristic display mode and reverting to a display that also shows temperatures between 96°C and 116°C.

Instrument cluster (IC), location / task GF54.30-P-3039Q