Engine Coolant Temperature Sensor (ECTS)

Description and Operation

Description

The engine coolant temperature sensor is located in the engine coolant passage in the cylinder head. The sensor (ECTS) detects the engine coolant temperature. The ECTS uses a thermistor whose resistance changes with temperature. The electrical resistance of the ECTS decreases as temperature rises and increases as temperature falls. A 5 V reference voltage is supplied to the ECTS through a resistor in the ECM; that is, the resistor in the ECM and the thermistor in the ECTS are connected in series. As the thermistor resistance in the ECTS changes with engine coolant temperature, the output voltage also changes. The ECM uses engine coolant temperature information to control ignition timing and fuel injection to prevent engine stalling and improve drivability. When the engine is cold, the ECM increases the fuel injection frequency and controls ignition timing using engine coolant temperature information to prevent engine stalling and improve drivability.

Specifications

Specification

Temperature		Resistance (kOhm)
°C	°F
-40	-40	48.14
-20	-4	14.13 - 16.83
0	32	5,79
20	68	2,31 - 2,59
40	104	1,15
60	140	0,59
80	176	0,32

Circuit Diagrams

Wiring Diagram

Harness Connector

Repair Procedures

Inspection

1. 1
   Turn the ignition off.
2. 2
   Disconnect the ECTS connector.
3. 3
   Remove the ECTS. (Refer to Removal)
4. 4
   With the sensor thermistor immersed in engine coolant, measure the resistance between ECTS terminals 3 and 4.
5. 5
   Make sure the resistance is within specification.

   Temperature		Resistance (kOhm)
   °C	°F
   -40	-40	48.14
   -20	-4	14.13 - 16.83
   0	32	5,79
   20	68	2,31 - 2,59
   40	104	1,15
   60	140	0,59
   80	176	0,32

Removal

1. 1
   Turn the ignition switch OFF and disconnect the negative (-) battery terminal.
2. 2
   Remove the air cleaner assembly. (Refer to Engine Mechanical System - "Air Cleaner")
3. 3
   Disconnect the engine coolant temperature sensor connector (A).
4. 4
   Remove the engine coolant temperature sensor (B) from the water outlet housing assembly.

   Note that engine coolant may leak when removing the engine coolant temperature sensor.

   

Installation

Install the component to the specified torque. Be aware that internal damage may occur if the component is dropped. In this case, inspect the component before installation. Insert the sensor into the mounting hole, taking care not to damage it during installation.

1. 1
   Install in the reverse order of removal.
2. 2
   Refill the engine coolant. (Refer to Engine Mechanical System - Cooling System)