Toyota 2GR-FE Manual page 309

DTC P0115
DTC P0117
DTC P0118
DESCRIPTION
A thermistor is built into the Engine Coolant Temperature (ECT) sensor, of which the resistance value
varies according to the ECT.
The structure of the sensor and its connection to the ECM are the same as those of the Intake Air
Temperature (IAT) sensor.
HINT:
When any of DTCs P0115, P0117 and P0118 are set, the ECM enters fail-safe mode. During fail-safe
mode, the ECT is estimated to be 80°C (176°F) by the ECM. Fail-safe mode continues until a pass
condition is detected.
DTC No. Proceed to
P0115 Step 1
P0117 Step 4
P0118 Step 2
HINT:
When any of these DTCs are set, check the ECT by entering the following menus on the intelligent tester:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / COOLANT TEMP.
Temperature Displayed
-40°C (-40°F)
140°C (284°F) or higher
MONITOR DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is used to monitor the ECT. The ECT sensor has a
thermistor with a resistance that varies according to the temperature of the engine coolant. When the
coolant temperature drops, the resistance in the thermistor increases. When the temperature rises, the
resistance drops. These variations in resistance are reflected in the output voltage from the sensor. The
ECM monitors the sensor voltage and uses this value to calculate the ECT. 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:
If the sensor output voltage is -40°C (-40°F) for 0.5 seconds or more, the ECM determines that there
is an open in the ECT sensor circuit, and sets DTC P0118. Conversely, if the voltage output is more
than 140°C (284°F) for 0.5 seconds or more, the ECM determines that there is a short in the sensor
circuit, and sets DTC P0117.
If the malfunction is not repaired successfully, a DTC is set 0.5 seconds after the engine is next
started.
2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
Engine Coolant Temperature Circuit Malfunc-
tion
Engine Coolant Temperature Circuit Low Input
Engine Coolant Temperature Circuit High Input
DTC Detection Condition
Open or short in Engine Coolant Temperature
(ECT) sensor circuit for 0.5 seconds (1 trip
detection logic)
Short in Engine Coolant Temperature (ECT)
sensor circuit for 0.5 seconds (1 trip detection
logic)
Open in Engine Coolant Temperature (ECT)
sensor circuit for 0.5 seconds (1 trip detection
logic)
Trouble Area
• Open or short in ECT sensor circuit
• ECT sensor
• ECM
• Short in ECT sensor circuit
• ECT sensor
• ECM
• Open in ECT sensor circuit
• ECT sensor
• ECM
Malfunction
Open circuit
Short circuit
ES–153
ES