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Last Modified: 11-27-2007 1.6 C
Service Category: Engine/Hybrid System Section: Engine Control
Model Year: 2008 Model: LX570 Doc ID: RM000000U5B05FX
Title: 3UR-FE ENGINE CONTROL: SFI SYSTEM: DESCRIPTION (2008 LX570)

DTC

P0102

Mass or Volume Air Flow Circuit Low Input

DTC

P0103

Mass or Volume Air Flow Circuit High Input

DESCRIPTION

The Mass Air Flow (MAF) meter is a sensor that measures the amount of air flowing through the throttle valve.

The ECM uses this information to determine the fuel injection time and to provide the appropriate air-fuel ratio.

Inside the MAF meter, there is a heated platinum wire which is exposed to the flow of intake air.

By applying a specific electrical current to the wire, the ECM heats it to a given temperature. The flow of incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to these components in the MAF meter. The voltage level is proportional to the airflow through the sensor, and the ECM uses it to calculate the intake air volume.

The circuit is constructed so that the platinum hot wire and the cold film element create a bridge circuit, and the power transistor is controlled so that the potentials of A and B remain equal to maintain the predetermined temperature.

HINT:

When any of these DTCs are stored, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is calculated by the ECM, according to the engine speed and throttle valve position. Fail-safe mode continues until a pass condition is detected.



DTC Code

DTC Detection Condition

Trouble Area

P0102

The Mass Air Flow (MAF) meter voltage is below 0.2 V for 3 seconds (1 trip detection logic).
  • Open or short in Mass Air Flow (MAF) meter circuit
  • MAF meter
  • ECM

P0103

The MAF meter voltage is higher than 4.9 V for 3 seconds (1 trip detection logic).
  • Open or short in MAF meter circuit
  • MAF meter
  • ECM

HINT:

When any of these DTCs is output, check the air-flow rate by entering the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF.

Mass Air Flow Rate (g/sec.)

Malfunction

Approximately 0.0
  • Open in Mass Air Flow (MAF) meter power source circuit
  • Open or short in VG circuit

271.0 or more

Open in E2G circuit

MONITOR DESCRIPTION

If there is a defect in the MAF meter or an open or short circuit, the voltage level deviates from the normal operating range. The ECM interprets this deviation as a malfunction in the MAF meter and stores DTC(s).

Example:

When the sensor output voltage remains at below 0.2 V, or higher than 4.9 V for more than 3 seconds, the ECM stores DTC(s).

If the malfunction is not repaired successfully, a DTC is stored 3 seconds after the engine is next started.

MONITOR STRATEGY

Related DTCs

P0102: MAF meter range check (Low voltage)

P0103: MAF meter range check (High voltage)

Required Sensors/Components (Main)

MAF meter

Required Sensors/Components (Related)

Crankshaft position sensor

Frequency of Operation

Continuous

Duration

3 seconds

MIL Operation

Immediate: Engine speed less than 4,000 rpm

2 driving cycles: Engine speed 4,000 rpm or more

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not stored

None

TYPICAL MALFUNCTION THRESHOLDS

P0102:

MAF meter voltage

Below 0.2 V

P0103:

MAF meter voltage

Higher than 4.9 V

COMPONENT OPERATING RANGE

MAF meter voltage

0.4 to 2.2 V

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

Read freeze frame data using the Techstream. Freeze frame data records 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.

PROCEDURE

1.

READ VALUE USING TECHSTREAM (MASS AIR FLOW RATE)

(a) Connect the Techstream to the DLC3.

(b) Start the engine.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF.

(e) Read the values displayed on the Techstream.

Result

Mass Air Flow Rate (g/sec.)

Proceed to

0.0

A

271.0 or more

B

Between 1.0 and 270.0*

C

HINT:

*: The value must change when the throttle valve is open or closed with the engine running.

A

2.

INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE)


(a) Disconnect the C3 Mass Air Flow (MAF) meter connector.

(b) Turn the engine switch on (IG).

(c) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

C3-1 (+B) - Body ground

Engine switch on (IG)

11 to 14 V
OK

3.

INSPECT MASS AIR FLOW METER


(a) Remove the Mass Air Flow (MAF) meter 3UR-FE ENGINE CONTROL: MASS AIR FLOW METER: REMOVAL (2008 LX570) .

(b) Inspect the MAF meter.

(1) Measure the voltage according to the value(s) in the table below.

OK:

Tester Connection

Condition

Specified Condition

2 (E2G) - 3 (VG)
  • Battery voltage applied to terminals 1 (+B) - 2 (E2G)
  • Air blown into the MAF meter

Voltage fluctuates

NOTICE:

While using the battery during inspection, do not bring the positive and negative tester probes too close to each other as a short circuit may occur.

OK

4.

CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)


(a) Disconnect the C3 MAF meter connector.

(b) Disconnect the C53 ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

C3-3 (VG) - C53-74 (VG)

Always

Below 1 Ω

C3-2 (E2G) - C53-75 (E2G)

Always

Below 1 Ω

C3-3 (VG) or C53-74 (VG) - Body ground

Always

10 kΩ or higher
OK

9.

CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - INTEGRATION RELAY)

(a) Check the EFI NO. 2 fuse.

(1) Remove the EFI NO. 2 fuse from the engine room relay block.

(2) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

EFI NO. 2 fuse

Always

Below 1 Ω

(3) Reinstall the EFI NO. 2 fuse.



(b) Disconnect the C3 MAF meter connector.

(c) Remove the integration relay from the engine room relay block.

(d) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

C3-1 (+B) - 1B-4

Always

Below 1 Ω

C3-1 (+B) or 1B-4 - Body ground

Always

10 kΩ or higher
OK

12.

CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)


(a) Disconnect the C3 MAF meter connector.

(b) Disconnect the C53 ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

C3-3 (VG) - C53-74 (VG)

Always

Below 1 Ω

C3-2 (E2G) - C53-75 (E2G)

Always

Below 1 Ω

C3-3 (VG) or C53-74 (VG) - Body ground

Always

10 kΩ or higher
OK

13.

CHECK HARNESS AND CONNECTOR (SENSOR GROUND)


(a) Disconnect the C3 MAF meter connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

C3-2 (E2G) - Body ground

Always

Below 1 Ω
OK