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:

Adjusting the set speed
To change the set speed, operate the lever until the desired set speed is obtained. 1 Increases the speed 2 Decreases the speed Fine adjustment: Momentarily move the lever in the desired direction. Large adjustment: Hold the lever in the desired direction. The set speed will be increased or dec ...

Driving monitor
■ Switching the display Items displayed can be switched by pressing the DISP switch. ■ Average fuel consumption Displays the average fuel consumption since the function was reset. Press and hold the DISP switch to reset when the average fuel consumption is displayed. Use ...

Check short circuit
If the wire harness is ground shorted as shown in fig. 5, Locate the section by conducting a resistance check with the body ground in step (b). Check the resistance with the body ground.  Disconnect connectors a and c and measure the resistance between terminals 1 and 2 ...

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