Toyota FJ Cruiser (GSJ 10, 15 series). Instruction - part 37

1GR-FE ENGINE CONTROL SYSTEM  –  SFI SYSTEM

ES–103

ES

TYPICAL MALFUNCTION THRESHOLDS

WIRING DIAGRAM

Refer to DTC P0100 (See page 

ES-92

).

CONFIRMATION DRIVING PATTERN

HINT:
Performing this confirmation pattern will activate the mass air flow performance monitor.

1. Connect the intelligent tester to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the tester ON.
4. Clear DTCs (See page 

ES-38

).

5. Start the engine, and warm it up until the engine coolant temperature reaches 70

°C (158°F) or higher.

6. Drive the vehicle at approximately 62 mph (100 km/h) for 20 seconds or more.
7. On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / 

PENDING CODES and check if any DTCs (any pending DTCs) are set.

Engine coolant temperature

70

°C (158°F) or more

IAT sensor circuit

OK

ECT sensor circuit

OK

CKP sensor circuit

OK

TP sensor circuit

OK

Canister pressure sensor circuit

OK

EVAP leak detection pump

OK

EVAP vent valve

OK

Both of following conditions 1 and 2 met

-

1. Averaged engine load value ratio

Less than 0.85, or more than 1.17 (varies with estimated engine load)

2. Averaged air-fuel ratio

Less than -20 %, or more than 20 %

Vehicle Speed

Approximately 62 mph

(100 km/h)

Idling

Warming Up

20 seconds or more

Time

A112632E01

ES–104

1GR-FE ENGINE CONTROL SYSTEM  –  SFI SYSTEM

ES

INSPECTION PROCEDURE

HINT:
Read freeze frame data using an intelligent tester. Freeze frame data record the engine condition when 
malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was 
moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other 
data, from the time the malfunction occurred.

(a) Connect an intelligent tester to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the tester ON.
(d) Select the following menu items: DIAGNOSIS / 

ENHANCED OBD II / DTC INFO / CURRENT CODES.

(e) Read DTCs.

Result

HINT:
If any DTCs other than P0101 are output, troubleshoot those 
DTCs first.

B

A

(a) Check the air induction system for vacuum leakage.

OK:

No leakage from air induction system.

NG

OK

OK:

PCV hose is connected correctly and is not damaged.

NG

OK

1

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0101)

Display (DTC Output)

Proceed To

P0101

A

P0101 and other DTCs

B

GO TO DTC CHART

2

CHECK AIR INDUCTION SYSTEM

REPAIR OR REPLACE AIR INDUCTION 
SYSTEM

3

CHECK PCV HOSE CONNECTIONS

REPAIR OR REPLACE PCV HOSE

REPLACE MASS AIR FLOW METER (See page 

ES-409

)

1GR-FE ENGINE CONTROL SYSTEM  –  SFI SYSTEM

ES–105

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.
HINT:
When any of DTCs P0110, P0112 and P0113 are set, the ECM enters fail-safe mode. During fail-safe 
mode, the IAT is estimated to be 20

°C (68°F) by the ECM. Fail-safe mode continues until a pass condition 

is detected.

DTC

P0110

Intake Air Temperature Circuit

DTC

P0112

Intake Air Temperature Circuit Low Input

DTC

P0113

Intake Air Temperature Circuit High Input

DTC No.

Proceed To

DTC Detection Conditions

Trouble Areas

P0110

Step 1

Open or short in Intake Air Temperature 
(IAT) sensor circuit for 0.5 seconds (1 trip 
detection logic)

•

Open or short in IAT sensor circuit

•

IAT sensor (built into MAF meter)

•

ECM

P0112

Step 4

Short in Intake Air Temperature (IAT) 
sensor circuit for 0.5 seconds (1 trip 
detection logic)

•

Short in IAT sensor circuit

•

IAT sensor (built into MAF meter)

•

ECM

P0113

Step 2

Open in Intake Air Temperature (IAT) 
sensor circuit for 0.5 seconds (1 trip 
detection logic)

•

Open in IAT sensor circuit

•

IAT sensor (built into MAF meter)

•

ECM

kΩ

Acceptable

°C (°F)

(Figure 1)

A056276E08

ES–106

1GR-FE ENGINE CONTROL SYSTEM  –  SFI SYSTEM

ES

HINT:
When any of these DTCs are set, check the IAT by selecting the following menu items on an intelligent 
tester: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / INTAKE AIR.

MONITOR DESCRIPTION

The ECM monitors the sensor voltage and uses this value to calculate the Intake Air Temperature (IAT).
When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a 
malfunction in the IAT 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 IAT sensor circuit, and sets DTC P0113. Conversely, if the voltage output is less than 
0.18 V for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit, and sets 
DTC P0112.
If the malfunction is not repaired successfully, a DTC is set 0.5 seconds after the engine is next started.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

P0110:

P0112:

P0113:

COMPONENT OPERATING RANGE

Temperature Displayed

Malfunctions

-40

°C (-40°F)

Open circuit

140

°C (284°F) or higher

Short circuit

Related DTCs

P0110: Intake air temperature sensor open/short (Fluctuating)
P0112: Intake air temperature sensor short (Low voltage)
P0113: Intake air temperature sensor open (High voltage)

Required Sensors/Components (Main)

Intake Air Temperature (IAT) sensor

Required sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

0.5 seconds

MIL Operation

Immediate

Sequence of Operation

None

Monitor runs whenever following DTCs not present

None

Intake air temperature sensor voltage

Less than 0.18 V, or more than 4.91 V

Intake air temperature sensor voltage

Less than 0.18 V

Intake air temperature sensor voltage

More than 4.91 V

Intake air temperature sensor voltage

0.18 V to 4.91 V