LEMON Manuals: Even more car manuals for everyone
Home >> Toyota >> 2004 >> Highlander Limited, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 1 (Engine Control System (SFI) - Diagnostics (2AZ-FE)) >> DTC P0115, P0117, P0118: Engine Coolant Temperature Circuit >> Monitor Description

Monitor Description

WARNING: This page is about a different variant/trim than selected.

The ECT sensor is used to monitor the engine coolant temperature. The ECT sensor has a thermistor that varies its resistance depending on the temperature of the engine coolant. When the coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. The variations in resistance are reflected in the voltage output from the sensor.

The ECM monitors the sensor voltage and uses this value to calculate the engine coolant temperature.

When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the ECT sensor and sets a DTC.

Example:

When the ECM calculates that the ECT is -40°C (-40°F) or more than 140°C (284°F) and if either condition continues 0.5 seconds or more, the ECM will set a DTC.