Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Engine coolant temperature circuit / Circuit description
Toyota Corolla (E120): 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 fail–safe 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 |
|
| 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 hand–held tester or the obd ii scan tool.
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 malfunction thresholds
Component operating range
Wiring diagram
Other materials:
Inspection procedure
Hint:
if dtc p0441 (purge flow), p0446 (vsv for ccv or vsv for pressure
switching valve), p0451, p0452
or p0453 is output with dtc p0442 or p0456 , first troubleshoot
dtc p0441, p0446, p0451, p0452 or p0453. If no malfunction is detected,
troubleshoot dtc
p0442 or p0456 next.
...
Circuit description
The park/neutral position switch detects the shift lever position and sends
signals to the ecm.
Monitor description
The park/neutral position switch detects the gearshift position and sends a
signal to the ecm.
For security, the park/neutral position switch detects the gearshift positio ...
Child restraint systems
Before installing a child
restraint system in the vehicle,
there are precautions
that need to be observed,
different types of child
restraint systems, as well as
installation methods, etc.,
written in this manual.
Use a child restraint system
when riding with a small child
that cannot properly use a ...