Circuit Description

A thermistor is built in the Engine Coolant Temperature (ECT) sensor and changes the resistance value according to the engine coolant temperature.

The structure of the sensor and connection to the ECM is the same as the Intake Air Temperature (IAT) sensor.

NOTE: If the ECM detects the DTC P0115, P0117 or P0118, it operates the fail-safe function in which the ECT is assumed to be 80° C (176° F).

Fig 1: DTC P0115, P0117 & P0118 Chart

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NOTE: After confirming DTC P0115, P0117 or P0118, use the OBD II scan tool or the hand-held tester to confirm the engine coolant temperature from the DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL.

NOTE:

TEMPERATURE DISPLAY

Displayed Temperature	Malfunction
-40° C (-40° F)	Open circuit
140° C (284° F) or more	Short circuit