Toyota Tacoma manuals

Toyota Corolla Repair Manual: Circuit description

A thermistor is built in the engine coolant temperature 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 those of the intake air temperature sensor.

Hint

: if the ecm detects the dtc p0115, p0117 or p0118, it operates the failsafe function in which the engine coolant temperature is assumed to be 80 c (176 F).

Dtc no.

Proceed to

Dtc detection condition

Trouble area

P0115 Step 1 Open or short in engine coolant temperature sensor circuit for 0.5 Seconds
  • Open or short in engine coolant temperature sensor circuit
  • engine coolant temperature sensor
  • ecm
P0117 Step 4 Short in engine coolant temperature sensor circuit for 0.5 Seconds
P0118 Step 2 Open in engine coolant temperature sensor circuit for 0.5 Seconds

Hint

: after confirming dtc p0115, p0117 or p0118, confirm the engine coolant temperature in the diagnosis/ enhanced obd ii/data list/all using the handheld tester or the obd ii scan tool.

Monitor description

Monitor description

The engine coolant temperature (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 the condition continues for 0.5 Sec or more, the ecm will set a dtc.

Monitor strategy

Typical enabling conditions

Typical enabling conditions

Typical malfunction thresholds

Typical malfunction thresholds

Component operating range

Component operating range

Wiring diagram

Wiring diagram

Inspection procedure

Engine coolant temperature circuit
Dtc p0115 engine coolant temperature circuit Dtc p0117 engine coolant temperature circuit low input Dtc p0118 engine coolant temperature circuit high input ...

Inspection procedure
Hint: if different dtcs related to different systems that have terminal e2 as the ground terminal are output simultaneously, terminal e2 may be open. Read freeze frame data using the hand-h ...

Other materials:

Towing your vehicle with 4 wheels on the ground
To prevent damage to your vehicle, perform the following procedures before towing. 1 Shift the shift lever to N. 2 Turn the engine switch to the ACC position (without a smart key system) or ACCESSORY mode (with a smart key system). (, 166) Ensure that the audio system and other powered device ...

Inspection procedure
Hint: if dtcs p0115, p0116, p0117, p0118 and p0125 are output simultaneously, the engine coolant temperature sensor circuit may be open or short. Perform the troubleshooting of dtc p0115, p0117 or p0118 first. Read freeze frame data using the hand-held tester or the obd ii scan to ...

Shifting the shift lever
Vehicles without a smart key system: While the engine switch is in the ON position, depress the brake pedal and move the shift lever. Vehicles with a smart key system: While the engine switch is in IGNITION ON mode, depress the brake pedal and move the shift lever. When shifting the shif ...

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