Component Description

The engine coolant temperature sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the ECM. The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.

Fig 1: Identifying ECT Sensor

Courtesy of NISSAN MOTOR CO., U.S.A.

VOLTAGE AND RESISTANCE REFERENCE CHART

Engine coolant temperature [°C (°F)]

Voltage⁽¹⁾ (V)

Resistance (kΩ)

-10 (14)

4.4

7.0 - 11.4

20 (68)

3.5

2.1 - 2.9

50 (122)

2.2

0.68 - 1.00

90 (194)

0.9

0.236 - 0.260

⁽¹⁾	This data is reference value and is measured between ECM terminal 73 (Engine coolant temperature sensor) and ground.

Fig 2: Resistance And Temperature Graph

Courtesy of NISSAN MOTOR CO., U.S.A.

CAUTION: Never use ECM ground terminals when measuring input/output voltage. Doing so may result in damage to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.