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:
Circuit description
The door key lock and unlock switch is built in the door lock motor.
Wiring diagram
Inspection procedure
1 Check door lock
2 Check wire harness (tvip ecu door lock)
Disconnect the tvip ecu and door lock connectors.
check the continuity between the terminals of the t ...
Installing tire pressure
warning valves and transmitters
(vehicles with a
tire pressure warning system)
When replacing tires or wheels,
tire pressure warning valves and transmitters must also be
installed.
When new tire pressure warning
valves and transmitters are
installed, new ID codes must be
registered in the tire pressure
warning computer and the tire
pressure warning system must
be initialized. ...
How to proceed with troubleshooting
The hand–held tester can be used at step 3, 4, 6, 9.
1 Vehicle brought to workshop
2 Customer problem analysis
3 Connect the obd ii scan tool or hand–held tester to dlc3
4 Check and clear dtc and freeze frame data
5 Visual inspection
6 Setting the check mode diagnosis
7 Proble ...