Toyota Avalon Service & Repair Manual: Mass or Volume Air Flow Sensor "A" Circuit Short to Battery (P010012,P010014)

Toyota Avalon Service & Repair Manual / Engine / A25a-fxs Engine Control / Sfi System / Mass or Volume Air Flow Sensor "A" Circuit Short to Battery (P010012,P010014)

DESCRIPTION

The mass air flow meter sub-assembly is a sensor that measures the intake air volume using the following built-in components:

  • By-pass duct (allows some of the intake air to flow past a silicon chip sensor)
  • Silicon chip sensor (uses a heater control bridge circuit and temperature sensor bridge circuit to detect the difference in the temperature of the intake air that passes the sensors positioned before and after the heater).
  • Control circuit (converts the difference in temperature into a pulse signal and performs correction)

Intake air flows past the temperature sensor (before heater), the heater, and then the temperature sensor (after heater) of the silicon chip sensor in the by-pass duct. As the intake air is warmed up when it is exposed to the heater, the temperature of the intake air as it flows past the temperature sensor (after heater) is higher than when it flows past the temperature sensor (before heater). The difference in temperature of the intake air at each temperature sensor varies depending on the velocity of the intake air that flows past the silicon chip sensor. The temperature sensor bridge circuit detects the difference in temperature and the control circuit converts it into a pulse signal and outputs it to the ECM. When the temperature detected by the temperature sensor (before heater) is higher than that detected by the temperature sensor (after heater), backflow of the intake air is detected.

The ECM calculates the intake air volume based on the pulse signal received from the mass air flow meter sub-assembly, and uses it to determine the fuel injection duration necessary for an optimal air-fuel ratio.

The heater control bridge circuit has a temperature sensor and power transistor, and maintains the heater temperature at a specific temperature.

HINT:

When DTCs are stored, the ECM enters fail-safe mode. During fail-safe mode, the ECM calculates the fuel injection duration based on the engine speed and throttle valve angle. Fail-safe mode continues until a pass condition is detected.

*1

Mass Air Flow Meter Sub-assembly

-

-

*a

Silicon Chip Sensor

*b

By-pass Duct

*c

Heater

*d

Heater Thermistor

*e

Intake Air

*f

Temperature Sensor (After Heater)

*g

Temperature Sensor (Before Heater)

*h

Air Flow

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

P010012

Mass or Volume Air Flow Sensor "A" Circuit Short to Battery

The mass air flow meter sub-assembly output frequency is higher than 9.8 kHz for 3 seconds or more (1 trip detection logic).

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

Comes on

DTC stored

SAE Code: P0103

P010014

Mass or Volume Air Flow Sensor "A" Circuit Short to Ground or Open

The mass air flow meter sub-assembly output frequency is less than 0.1 kHz for 3 seconds or more (1 trip detection logic).

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

Comes on

DTC stored

SAE Code: P0102

MONITOR DESCRIPTION

If there is a defect or an open or short circuit in the mass air flow meter sub-assembly, the frequency level deviates from the normal operating range. The ECM interprets this deviation as a malfunction in the mass air flow meter sub-assembly circuit and stores a DTC.

Example:

When the sensor output frequency remains less than 0.1 kHz, or higher than 9.8 kHz for 3 seconds, the ECM stores a DTC.

MONITOR STRATEGY

Related DTCs

P0102: Mass air flow meter range check (low frequency)

P0103: Mass air flow meter range check (high frequency)

Required Sensors/Components (Main)

Mass air flow meter sub-assembly

Required Sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

3 seconds

MIL Operation

Immediate

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored

None

Both of the following conditions are met

-

Auxiliary battery voltage

8 V or higher

Power switch

On (IG)

TYPICAL MALFUNCTION THRESHOLDS

P0102

Mass air flow meter output frequency

Less than 0.1 kHz

P0103

Mass air flow meter output frequency

Higher than 9.8 kHz

CONFIRMATION DRIVING PATTERN

HINT:

  • After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.

    Click here

  • When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.

    Click here

  1. Connect the Techstream to the DLC3.
  2. Turn the power switch on (IG).
  3. Turn the Techstream on.
  4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
  5. Turn the power switch off and wait for at least 30 seconds.
  6. Turn the power switch on (IG).
  7. Turn the Techstream on.
  8. Wait 5 seconds or more [A].
  9. Enter the following menus: Powertrain / Engine / Trouble Codes [B].
  10. 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.
  11. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
  12. Input the DTC: P010012 or P010014.
  13. 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

    HINT:

    • If the judgment result is NORMAL, the system is normal.
    • If the judgment result is ABNORMAL, the system has a malfunction.
    • If the judgment result is INCOMPLETE, perform steps [A] through [B] again.
    • [A] to [B]: Normal judgment procedure.

      The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.

    • When clearing the permanent DTCs, do not disconnect the cable from the auxiliary battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Vehicle Control History may be stored in the hybrid vehicle control ECU assembly if the engine is malfunctioning. Certain vehicle condition information is recorded when Vehicle Control History is stored. Reading the vehicle conditions recorded in both the Freeze Frame Data and Vehicle Control History can be useful for troubleshooting.

    Click here

    (Select Powertrain in Health Check and then check the time stamp data.)

    Click here

  • If any "Engine Malfunction" Vehicle Control History item has been stored in the hybrid vehicle control ECU assembly, make sure to clear it. However, as all Vehicle Control History items are cleared simultaneously, if any Vehicle Control History items other than "Engine Malfunction" are stored, make sure to perform any troubleshooting for them before clearing Vehicle Control History.

    Click here

HINT:

Read Freeze Frame Data using the Techstream. The ECM records vehicle and driving condition information as Freeze Frame Data the moment a DTC is stored. 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.

CHECK TERMINAL VOLTAGE (POWER SOURCE OF MASS AIR FLOW METER SUB-ASSEMBLY)

*a

Front view of wire harness connector

(to Mass Air Flow Meter Sub-assembly)

(a) Disconnect the mass air flow meter sub-assembly connector.

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

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

C28-3 (5V) - C28-2 (E2G)

Power switch on (IG)

4.8 to 5.2 V

C28-1 (FG) - C28-2 (E2G)

Power switch on (IG)

4.8 to 5.2 V

NG

GO TO STEP 5

OK

2.

REPLACE MASS AIR FLOW METER SUB-ASSEMBLY

(a) Replace the mass air flow meter sub-assembly.

Click here

HINT:

Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly.

Click here

NEXT

3.

CLEAR DTC

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Clear the DTCs.

Powertrain > Engine > Clear DTCs

(e) Turn the power switch off and wait for at least 30 seconds.

NEXT

4.

CHECK WHETHER DTC OUTPUT RECURS (DTC P010012 OR P010014)

(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(b) Enter the following menus: Powertrain / Engine / Trouble Codes.

(c) Read the DTCs.

Powertrain > Engine > Trouble Codes

Result

Proceed to

DTCs are not output

A

DTC P010012 or P010014 is output

B

A

END

B

REPLACE ECM

5.

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

(a) Disconnect the mass air flow meter sub-assembly 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

C28-3 (5V) - C55-78 (VCVG)

Always

Below 1 Ω

C28-1 (FG) - C55-101 (VG)

Always

Below 1 Ω

C28-2 (E2G) - C55-79 (E2G)

Always

Below 1 Ω

C28-3 (5V) or C55-78 (VCVG) - Body ground and other terminals

Always

10 kΩ or higher

C28-1 (FG) or C55-101 (VG) - Body ground and other terminals

Always

10 kΩ or higher

C28-2 (E2G) or C55-79 (E2G) - Body ground and other terminals

Always

10 kΩ or higher

OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

    Fuel Rail / System Pressure - Too High (P008800)

    Mass or Volume Air Flow Sensor "A" Signal Plausibility Failure (P010064)

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