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Coolant temperature

Coolant temperature


Engine coolant temperature sensor

From the temperature sensor that is mounted in the intake manifold, the Motronic control module receives information about the engine (coolant) temperature.

The resistance in the temperature sensor's built in resistor varies depending on the temperature, which also means that the voltage level varies on the signal into the control module pin 45.

How resistance and voltage vary in relation to engine temperature is made clear in the following table.

°C

°F

Voltage (approx. V)

Resistance (approx. kOhm)

-30

-22

4,8

20-30

-10

14

4,5

8,3-10,6

0

32

4,3

5,2-6,4

20

68

3,5

2,3-2,7

40

104

2,7

1,0-1,3

60

140

1,9

0,56-0,67

80

176

1,2

0,30-0,36

90

194

0,9

0,20-0,24



At low temperatures the control module gets a high signal voltage from the sensor, whereas a high temperature brings about a low signal voltage.

The temperature sensor signal is grounded together with several other sensors in the control module pin 30.

If an open circuit occurs the control module chooses a fixed value, equivalent to 80°C (176°F).