Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection

INSPECTION








Using Scan tool

Check Item: Engine Coolant Temperature Sensor.
Data Display: Sensor temperature.
Check Conditions: Ignition Switch ON or engine running.

With coolant temperature of -20°C (-4°F): test specification of -20°C.
With coolant temperature of 0°C (0°F): test specification of 0°C.
With coolant temperature of 20°C (68°F): test specification of 20°C.
With coolant temperature of 40°C (104°F): test specification of 40°C.
With coolant temperature of 80°C (176°F): test specification of 80°C.

Sensor Inspection

1. Remove Engine Coolant Temperature Sensor from the intake manifold.





2. With temperature sensing portion of Engine Coolant Temperature Sensor immersed in hot water, check resistance.

With temperature 0°C (32°F): Resistance 5.9 k ohms.
With temperature 20°C (68°F): Resistance 2.5 k ohms.
With temperature 40°C (104°F): Resistance 1.1 k ohms.
With temperature 80°C (176°F): Resistance 0.3 k ohms.

3. If the resistance deviates from the standard value greatly, replace the sensor.

Harness Inspection Procedure





1. Check for continuity of the ground circuit.
- Connector disconnected.

If OK - go to step 2.
If not OK - Repair the harness (H1 - C50-5 12).





2. Measure the power supply voltage.
- Connector disconnected.
- Ignition Switch ON.
- Voltage should be 4.5 - 4.9 volts

If OK - END
If not OK - Repair the harness (H2 - C50-5 21).

Troubleshooting Hints
If the fast idle speed is not enough or the engine gives off dark smoke during the engine warm-up operation, the Engine Coolant Temperature Sensor might be the causes.