Toyota Tundra Service Manual: Mass Air Flow Circuit Low (P0102,P0103)

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 the wire and internal thermistor. 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 temperature sensor 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 either of these DTCs is stored, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is calculated by the ECM according to the engine RPM and throttle valve position. Fail-safe mode continues until a pass condition is detected.

DTC No.

DTC Detection Condition

Trouble Area

P0102

Mass air flow meter voltage is below 0.2 V for 3 seconds

(1 trip detection logic: Engine speed is less than 4000 rpm)

(2 trip detection logic: Engine speed is 4000 rpm or more).

  • Open or short in mass air flow meter circuit
  • Mass air flow meter
  • ECM

P0103

Mass air flow meter voltage is higher than 4.9 V for 3 seconds

(1 trip detection logic: Engine speed is less than 4000 rpm)

(2 trip detection logic: Engine speed is 4000 rpm or more).

  • Open or short in mass air flow meter circuit
  • Mass air flow meter
  • ECM

HINT:

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

Mass Air Flow Rate (gm/sec.)

Malfunction

Approximately 0.0

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

160.0 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 a DTC.

Example:

When the sensor output voltage remains at less than 0.2 V, or more than 4.9 V for more than 3 seconds, the ECM stores a DTC.

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 4000 rpm

2 driving cycles: Engine speed 4000 rpm or more

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not present

None

TYPICAL MALFUNCTION THRESHOLDS

P0102

MAF meter voltage

Less than 0.2 V

P0103

MAF meter voltage

More than 4.9 V

COMPONENT OPERATING RANGE

MAF meter voltage

0.4 V to 2.2 V

CONFIRMATION DRIVING PATTERN

  1. Connect the Techstream to the DLC3.
  2. Turn the ignition switch to ON and turn the Techstream on.
  3. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).
  4. Turn the ignition switch off and wait for at least 30 seconds.
  5. Turn the ignition switch to ON and turn the Techstream on [A].
  6. Start the engine.
  7. Idle the engine for 5 seconds [B].
  8. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [C].
  9. Read the pending DTCs.

    HINT:

    • If a pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
  10. Run the engine at an engine speed of 4000 rpm or more for 5 seconds [D].
  11. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [E].
  12. Read the pending DTCs.

    HINT:

    • If a pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
  13. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
  14. Input the DTC: P0102 or P0103.
  15. Check the DTC judgment result.

    Techstream Display

    Description

    NORMAL

    • DTC judgment completed
    • System normal

    ABNORMAL

    • DTC judgment completed
    • System abnormal

    INCOMPLETE

    • DTC judgment not completed
    • Perform driving pattern after confirming DTC enabling conditions

    N/A

    • Unable to perform DTC judgment
    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    HINT:

    • If the judgment result shows NORMAL, the system is normal.
    • If the judgment result shows ABNORMAL, the system has a malfunction.
    • If the judgment result shows INCOMPLETE or N/A, perform steps [B] through [C] again.
  16. If no pending DTC is output, perform a universal trip and check for permanent DTCs (See page ).

    HINT:

    • If a permanent DTC is output, the system is malfunctioning.
    • If no permanent DTC is output, the system is normal.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

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 DTC OUTPUT

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(e) Read DTCs.

Result

Result

Proceed to

DTC P0102 is output

A

DTC P0103 is output

B

B

GO TO STEP 5

A

2.

INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE)

(a) Disconnect the mass air flow meter connector.

(b) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

D7-1 (+B) - Body ground

Ignition switch ON

11 to 14 V

NG

GO TO STEP 7

OK

3.

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

(a) Disconnect the mass air flow meter connector.

(b) Disconnect the ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D7-3 (VG) - D74-74 (VG)

Always

Below 1 Ω

D7-2 (E2G) - D74-75 (E2G)

Always

Below 1 Ω

D7-3 (VG) or D74-74 (VG) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

INSPECT MASS AIR FLOW METER

(a) Inspect the mass air flow meter, referring to the On-vehicle inspection for mass air flow meter (See page ).

(b) Inspect the mass air flow meter, referring to the inspection for mass air flow meter (See page ).

(c) Inspect the function of the mass air flow meter.

(1) Connect the Techstream to the DLC3.

(2) Turn the ignition switch to ON.

(3) Turn the Techstream on.

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

(5) Start the engine.

(6) Check that the MAF value changes when the engine is raced.

OK:

The reading changes.

HINT:

Perform "Inspection After Repair" after replacing the mass air flow meter (See page ).

OK

REPLACE ECM

NG

REPLACE MASS AIR FLOW METER

5.

CHECK HARNESS AND CONNECTOR (SENSOR GROUND)

(a) Disconnect the mass air flow meter connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D7-2 (E2G) - Body ground

Always

Below 1 Ω

HINT:

Perform "Inspection After Repair" after replacing the mass air flow meter (See page ).

OK

REPLACE MASS AIR FLOW METER

NG

6.

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

(a) Disconnect the mass air flow meter connector.

(b) Disconnect the ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D7-3 (VG) - D74-74 (VG)

Always

Below 1 Ω

D7-2 (E2G) - D74-75 (E2G)

Always

Below 1 Ω

D7-3 (VG) or D74-74 (VG) - Body ground

Always

10 kΩ or higher

OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.

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

(a) Disconnect the mass air flow meter connector.

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D7-1 (+B) - 2B-4

Always

Below 1 Ω

D7-1 (+B) or 2B-4 - Body ground

Always

10 kΩ or higher

OK

CHECK ECM POWER SOURCE CIRCUIT

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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