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:
Meter display
■ Locations of gauges and meters
The units of measure may differ depending on the intended destination of
the vehicle.
Tachometer
Displays the engine speed in revolutions per minute
Outside temperature
Displays the outside temperature within the range of -40ºF (-40ºC) to 140ºF
(60ºC)
...
Hood
Adjustment
Hint:
since the centering bolt is used as a hood hinge and hood lock
set bolt, the hood and hood lock can not be adjusted with it on.
Substitute a bolt with washer for the centering bolt.
1. Inspect hood sub–assy
Check that the clearance is within the standard value.
...
Wiper rubber lh
Replacement
1. Remove fr wiper blade lh
remove the front wiper blade lh from the front wiper arm lh.
Notice:
do not fold down the front wiper arm with the front wiper blade being removed
from it.
2. Remove wiper rubber lh
remove the front wiper rubber lh from the front wi ...