Lexus IS250 IS220d GSE20 ALE20 4GR-FSE ENGINE CONTROL SYSTEM

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

READ VALUE OF INTAKE AIR TEMPERATURE SENSOR (INTAKE AIR)

CHECK INTAKE AIR TEMPERATURE SENSOR (CHECK FOR OPEN IN SENSOR)

CHECK ECM (CHECK FOR OPEN IN ECM)

CHECK INTAKE AIR TEMPERATURE SENSOR (CHECK FOR SHORT IN SENSOR)

CHECK ECM (CHECK FOR SHORT IN ECM)

DTC P0110 Intake Air Temperature Circuit Malfunction

DTC P0112 Intake Air Temperature Circuit Low Input

DTC P0113 Intake Air Temperature Circuit High Input

DESCRIPTION

Dtc P0110 Intake Air Temperature Circuit Malfunction. 4GR-FSE ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

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 No.	Proceed to	DTC Detection Condition	Trouble Area
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

HINT:

When any of these DTCs are set, check the IAT by entering the following menus on the intelligent tester: Power train / Engine / Data List / Intake Air.

Temperature Displayed	Malfunction
-40°C (-40°F)	Open circuit
140°C (284°F) or higher	Short circuit

WIRING DIAGRAM

Dtc P0110 Intake Air Temperature Circuit Malfunction. 4GR-FSE ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

INSPECTION PROCEDURE

HINT:

If other DTCs relating to different systems that have terminal E3 as the ground terminal are output simultaneously, terminal E3 may have an open circuit.

Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions 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 .

1.READ VALUE OF INTAKE AIR TEMPERATURE SENSOR (INTAKE AIR)

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG).

Turn the tester ON.

Enter the following menus: Power train / Engine / Data List / Intake Air.

Read the value displayed on the tester.

Standard:
Same as actual Intake Air Temperature (IAT).

Result:
Temperature Displayed Proceed to
-40 °C (-40°F) A
140°C (284°F) or higher B
Same as actual IAT C

HINT:

If there is an open circuit, the intelligent tester indicates -40°C (-40°F).

If there is a short circuit, the intelligent tester indicates 140°C (284°F) or higher.

Go to step 4

CHECK FOR INTERMITTENT PROBLEMS

A

2.CHECK INTAKE AIR TEMPERATURE SENSOR (CHECK FOR OPEN IN SENSOR)

Confirm good connection at the Mass Air Flow (MAF) meter.

Disconnect the E29 MAF meter connector.

Connect terminals THA and E2 of the MAF meter wire harness side connector.

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG).

Turn the tester ON.

Enter the following menus: Power train / Engine / Data List / Intake Air.

Read the value displayed on the tester.

Standard:
140°C (284°F) or higher

Reconnect the MAF meter connector.

REPLACE MASS AIR FLOW METER

NG

3.CHECK ECM (CHECK FOR OPEN IN ECM)

Confirm good connection at the ECM.

Disconnect the E29 MAF meter connector.

Connect terminals THA and E3 of the E5 ECM connector.

HINT:

Before checking, do visual and contact pressure checks on the ECM connector.

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG).

Turn the tester ON.

Enter the following menus: Power train / Engine / Data List / Intake Air.

Read the value displayed on the tester.

Standard:
140°C (284°F) or higher

Reconnect the MAF meter connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE ECM

4.CHECK INTAKE AIR TEMPERATURE SENSOR (CHECK FOR SHORT IN SENSOR)

Disconnect the E29 MAF meter connector.

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG).

Turn the tester ON.

Enter the following menus: Power train / Engine / Data List / Intake Air.

Read the value displayed on the tester.

Standard:
-40°C (-40°F) or higher

Reconnect the MAF meter connector.

REPLACE MASS AIR FLOW METER

NG

5.CHECK ECM (CHECK FOR SHORT IN ECM)

Disconnect the E5 ECM connector.

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG).

Turn the tester ON.

Enter the following menus: Power train / Engine / Data List / Intake Air.

Read the value displayed on the tester.

Standard:
-40°C (-40°F) or higher

Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE ECM

Temperature Displayed	Proceed to
-40 °C (-40°F)	A
140°C (284°F) or higher	B
Same as actual IAT	C