Toyota FJ Cruiser (GSJ 10, 15 series). Instruction — part 39
1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES–111
ES
DESCRIPTION
The Intake Air Temperature (IAT) sensor, mounted on the Mass Air Flow (MAF) meter, monitors the IAT.
The IAT sensor has a built in thermistor with a resistance that varies according to the temperature of the
intake air. When the IAT is low, the resistance of the thermistor increases. When the temperature is high,
the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes (See
Fig. 1).
The IAT sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.
Resistor R and the IAT sensor are connected in series. When the resistance value of the IAT sensor
changes, according to changes in the IAT, the voltage at terminal THA also varies. Based on this signal,
the ECM increases the fuel injection volume when the engine is cold to improve driveability.
MONITOR DESCRIPTION
The ECM performs OBD II monitoring based on the values from the intake air temperature sensor. If there
is no change of the sensor value within the normal range, the ECM will not be able to perform OBD II
monitoring or will misdiagnose that there is a malfunction in the sensor. The ECM detects the stuck intake
air temperature sensor value by performing monitoring after the ignition switch is turned OFF or START.
MONITOR STRATEGY
DTC
P0111
Intake Air Temperature Sensor Gradient Too
High
DTC No.
DTC Detection Conditions
Trouble Areas
P0111
When either of following conditions met (2 trip detection
logic):
•
The intake air temperature rise is large, from the previous
trip warm-up to the following trip.
•
When the change in the intake air temperature after
engine start is less than the threshold value.
Mass air flow meter
Related DTCs
P0111: Intake air temperature sensor rationality (After engine stop)
P0111: Intake air temperature sensor rationality (After cold engine
start)
Fig. 1
Resistance
Acceptable
Temperature
(kΩ)
(°C)
(°F)
A067628E14
ES–112
1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
TYPICAL ENABLING CONDITIONS
All:
After engine stop:
After cold engine start:
TYPICAL MALFUNCTION THRESHOLDS
After engine stop:
After cold engine start:
WIRING DIAGRAM
Refer to DTC P0110 (See page
).
INSPECTION PROCEDURE
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch ON.
(c) Turn the tester ON.
(d) Enter the following menus: DIAGNOSIS / ENHANCED
OBD II / DTC INFO / CURRENT CODES.
(e) Read DTCs.
Required Sensors/Components (Main)
Intake Air Temperature (IAT) sensor
Required Sensors/Components (Sub)
Engine Coolant Temperature (ECT) sensor and Mass Air Flow (MAF)
meter
Frequency of Operation
Once per driving cycle
Duration
10 seconds or more
MIL Operation
2 driving cycles
Sequence of Operation
None
Monitor runs whenever following DTCs are not present
-
Battery voltage
10.5 V or more
Time after engine start
10 seconds or more
ECT sensor circuit
OK
ECT in previous driving cycle
80
°C (176°F) or more
Accumulated MAF amount in previous driving cycle
7,000 g or more
ECT when 30 minutes elapsed after engine stop
20
°C (68°F) or more
Key-off duration
5 hours
Time after engine start
10 seconds or more
ECT sensor circuit
OK
ECT
70
°C (158°F) or more
Accumulated MAF amount
7,000 g or more
One of the following conditions 1 or 2 is met:
-
1. Duration while engine load is low
120 seconds or more
2. Duration while engine load is high
10 seconds or more
IAT change
Less than 1
°C (2°F)
IAT change
Less than 1
°C (2°F)
1
CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0111)
1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES–113
ES
Result
HINT:
If any DTCs other than P0111 are output, troubleshoot
those DTCs first.
B
A
Display (DTC Output)
Proceed To
P0111 and other DTCs
A
P0111
B
REPLACE MASS AIR FLOW METER (See
page
)
GO TO DTC CHART (See page
)
ES–114
1GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
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.
HINT:
When any of these DTCs are set, check the ECT by selecting the following menu items on an intelligent
tester: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / COOLANT TEMP.
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 is low, the resistance in the thermistor increases. When the temperature is high, the
resistance drops.
These 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 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 voltage output is more than 4.91 V 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 less than
0.14 V 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.
MONITOR STRATEGY
DTC
P0115
Engine Coolant Temperature Circuit
DTC
P0117
Engine Coolant Temperature Circuit Low Input
DTC
P0118
Engine Coolant Temperature Circuit High Input
DTC No.
Proceed To
DTC Detection Conditions
Trouble Areas
P0115
Step 1
Open or short in Engine Coolant
Temperature (ECT) sensor circuit for 0.5
seconds (1 trip detection logic)
•
Open or short in ECT sensor circuit
•
ECT sensor
•
ECM
P0117
Step 4
Short in Engine Coolant Temperature
(ECT) sensor circuit for 0.5 seconds (1
trip detection logic)
•
Short in ECT sensor circuit
•
ECT sensor
•
ECM
P0118
Step 2
Open in Engine Coolant Temperature
(ECT) sensor circuit for 0.5 seconds (1
trip detection logic)
•
Open in ECT sensor circuit
•
ECT sensor
•
ECM
Temperature Displayed
Malfunctions
-40
°C (-40°F)
Open circuit
140
°C (284°F) or higher
Short circuit
Related DTCs
P0115: Engine coolant temperature sensor open/short (Fluctuating)
P0117: Engine coolant temperature sensor short (Low voltage)
P0118: Engine coolant temperature sensor open (High voltage)
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