engine TOYOTA RAV4 2006 Service Repair Manual

2AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEMES–109
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 the
engine is started (short soak or long soak).
DTC P0111Intake Air Temperature Sensor Gradient Too
High
DTC No. DTC Detection Condition Trouble Area
P0111When either condition below is met:
1. The intake air temperature rise is large, from the
previous trip warm-up to the following trip (2 trip
detection logic).
2. When the change in the intake air temperature after
engine start is less than the threshold value.Mass air flow meter assembly
A067628E18

ES–1102AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
MONITOR STRATEGY
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 ES-88).
INSPECTION PROCEDURE
(a) Connect the intelligent tester to the DLC3.
Related DTCsP0111: Intake air temperature sensor rationality (After engine stop)
P0111: Intake air temperature sensor rationality (After cold engine
start)
Required Sensors/Components (Main) Intake Air Temperature (IAT) sensor
Required Sensors/Components (Sub) -
Frequency of Operation Once per driving cycle
Duration 5 hours or more
MIL Operation 2 driving cycles
Sequence of Operation None
Monitor runs whenever following DTCs are not present None
Time after engine start 10 seconds or more
Battery voltage 10.5 V or more
ECT sensor circuit OK
ECT change since engine Less than 180
C (356F)
ECT before engine stop 70
C (158F) or more
Time that MAF is low before engine stop 70 minutes
Accumulated MAF amount before engine stop 3,451 g or more
Key-off duration 30 minutes
Key-off duration 5 hours
Time after engine start 10 seconds or more
ECT sensor circuit OK
ECT 70
C (158F) or more
Accumulated MAF amount 3,451 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 (2F)
IAT change Less than 1
C (2F)
1CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0111)

2AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEMES–111
ES
(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.
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
GO TO DTC CHART

ES–1122AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
DESCRIPTION
A thermistor, whose resistance value varies according to the ECT, is built into the Engine Coolant
Temperature (ECT) sensor.
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 (176F) 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 the 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 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 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.
DTC P0115Engine Coolant Temperature Circuit Malfunc-
tion
DTC P0117 Engine Coolant Temperature Circuit Low Input
DTC P0118 Engine Coolant Temperature Circuit High Input
DTC No. DTC Detection Conditions Trouble Areas
P0115Open or short in ECT sensor circuit for 0.5 seconds (1 trip
detection logic)• Open or short in ECT sensor circuit
• ECT sensor
•ECM
P0117Short in ECT sensor circuit for 0.5 seconds (1 trip detection
logic)• Short in ECT sensor
• ECT sensor
•ECM
P0118Open in ECT sensor circuit for 0.5 seconds (1 trip detection
logic)• Open in ECT sensor circuit
• ECT sensor
•ECM
Temperature Displayed Malfunctions
-40
C (-40F) Open circuit
140
C (284F) or higher Short circuit