Brand:

Toyota

Model Name:

4Runner GRN210 215 UZN210 215

Manual:

Repair Manual

Section:

1Gr-Fe Engine Control System

Title:

Sfi System

  1. Description

  2. Monitor description

  3. Monitor strategy

  4. Typical enabling conditions

  5. Typical malfunction thresholds

  6. Component operating range

  7. Wiring diagram

  8. Inspection procedure

  9. Read value of intelligent tester (mass air flow rate)

  10. Inspect mass air flow meter (power source voltage)

  11. Inspect ecm (vg voltage)

  12. Check harness and connector (mass air flow meter - ecm)

  13. Check harness and connector (mass air flow meter - efi relay)

  14. Inspect ecm (sensor ground)

  15. Check harness and connector (mass air flow meter - ecm)

DTC P0100 Mass or Volume Air Flow Circuit

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 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 specific temperature. The flow of incoming air cools both the wire and an internal thermistor, changing 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 air flow 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 provide 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 set, 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.

Open or short in MAF meter circuit 4Runner


DTC No.
DTC Detection Conditions
Trouble Areas
P0100
Open or short in Mass Air Flow (MAF) meter circuit for 3 seconds
  1. Open or short in MAF meter circuit
  2. MAF meter
  3. ECM
P0102
Open in Mass Air Flow (MAF) meter circuit for 3 seconds
  1. Open in MAF meter circuit
  2. Short in ground circuit
  3. MAF meter
  4. ECM
P0103
Short in Mass Air Flow (MAF) meter circuit for 3 seconds
  1. Short in MAF meter circuit (+B circuit)
  2. MAF meter
  3. ECM
HINT:
When any of these DTCs are set, check the air-flow rate by selecting the following menu items on an intelligent tester: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / MAF.

Mass Air Flow Rate (gm/s)
Malfunctions
Approximately 0.0
  1. Open in Mass Air Flow (MAF) meter power source circuit
  2. Open or short in VG circuit
271.0 or more
Open in EVG 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 sets a DTC.
Example:
  1. When the sensor voltage output remains less than 0.2 V, or more than 4.9 V, for more than 3 seconds, the ECM sets a DTC.
  2. If the malfunction is not repaired successfully, a DTC is set 3 seconds after the engine is next started.

MONITOR STRATEGY


Related DTCs
P0100: Mass air flow meter range check (Fluctuating)
P0102: Mass air flow meter range check (Low voltage)
P0103: Mass air flow 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 RPM less than 4,000 rpm
2 driving cycles: Engine RPM 4,000 rpm or more
Sequence of Operation
None

TYPICAL ENABLING CONDITIONS


The monitor will run whenever these DTCs are not present
None

TYPICAL MALFUNCTION THRESHOLDS


P0100:
Mass air flow meter voltage
Less than 0.2 V, or more than 4.9 V

P0102:
Mass air flow meter voltage
Less than 0.2 V

P0103:
Mass air flow meter voltage
More than 4.9 V

COMPONENT OPERATING RANGE


Mass air flow meter voltage
Between 0.4 V and 2.2 V

WIRING DIAGRAM


Connect the intelligent tester to the DLC3. 4Runner


INSPECTION PROCEDURE

HINT:
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
1.READ VALUE OF INTELLIGENT TESTER (MASS AIR FLOW RATE)

  1. Connect the intelligent tester to the DLC3.

  1. Start the engine.

  1. Turn the tester on.

  1. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / MAF.

  1. Read the values displayed on the tester.

    Result:

    Mass Air Flow Rate (gm/s)
    		Proceed to
    0.0
    		A
    271.0 or more
    		B
    Between 1.0 and 270.0 (*1)
    		C
    *1: The value must be changed when the throttle valve is open or closed.


Bnext
Go to step 6

Cnext
CHECK FOR INTERMITTENT PROBLEMS
A
next down

2.INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE)
  1. Disconnect the M1 Mass Air Flow (MAF) meter connector. 4Runner

  2. Disconnect the M1 Mass Air Flow (MAF) meter connector.

  1. Turn the ignition switch on.

  1. Measure the voltage between the terminal of the wire harness side connector and body ground.

    Standard voltage:
    Tester Connections
    		Specified Conditions
    +B (M1-1) - Body ground
    		9 to 14 V

  1. Reconnect the MAF meter connector.



NGnext
Go to step 5
OK
next down

3.INSPECT ECM (VG VOLTAGE)
  1. Start the engine. 4Runner

  2. Start the engine.

  1. Measure the voltage between the terminals of the E4 ECM connector.

    HINT:
    The transmission gear selector lever should be in the P or N position and the A/C switch should be turned off.
    Standard voltage:
    Tester Connections
    		Conditions
    		Specified Conditions
    VG (E4-30) - E2G (E4-29)
    		Engine idling
    		0.5 to 3.0 V


OKnext
REPLACE ECM
NG
next down

4.CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
  1. Disconnect the M1 MAF meter connector. 4Runner

  2. Disconnect the M1 MAF meter connector.

  1. Disconnect the E4 ECM connector.

  1. Measure the resistance.

    Standard resistance (Check for open):
    Tester Connections
    		Specified Conditions
    VG (M1-3) - VG (E4-30)
    		Below 1 Ω
    E2G (M1-2) - E2G (E4-29)
    		Below 1 Ω
    Standard resistance (Check for short):
    Tester Connections
    		Specified Conditions
    VG (M1-3) or VG (E4-30) - Body ground
    		10 kΩ or higher

  1. Reconnect the MAF meter connector.

  1. Reconnect the ECM connector.



NGnext
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
next down
REPLACE MASS AIR FLOW METER

5.CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - EFI RELAY)
  1. Inspect the EFI No. 2 fuse.Remove the EFI No. 2 fuse from the engine room R/B.Measure the EFI No. 2 fuse resistance.Standard resistance:Below 1 ΩReinstall the EFI No. 2 fuse. 4Runner

  2. Inspect the EFI No. 2 fuse.

    1. Remove the EFI No. 2 fuse from the engine room R/B.

    2. Measure the EFI No. 2 fuse resistance.

      Standard resistance:
      Below 1 Ω

    3. Reinstall the EFI No. 2 fuse.

  1. Disconnect the M1 MAF meter connector.

  1. Remove the EFI relay from the engine room R/B.

  1. Measure the resistance.

    Standard resistance (Check for open):
    Tester Connections
    		Specified Conditions
    +B (M1-1) - EFI relay (3)
    		Below 1 Ω
    Standard resistance (Check for short):
    Tester Connections
    		Specified Conditions
    +B (M1-1) or EFI relay (3) - Body ground
    		10 kΩ or higher

  1. Reconnect the MAF meter connector.

  1. Reinstall the EFI relay.



NGnext
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
next down
CHECK ECM POWER SOURCE CIRCUIT

6.INSPECT ECM (SENSOR GROUND)
  1. Check the resistance.Standard resistance:Tester ConnectionsSpecified ConditionsE2G (E4-29) - Body groundBelow 1 Ω 4Runner

  2. Check the resistance.

    Standard resistance:
    Tester Connections
    		Specified Conditions
    E2G (E4-29) - Body ground
    		Below 1 Ω


NGnext
REPLACE ECM
OK
next down

7.CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
  1. Disconnect the M1 MAF meter connector. 4Runner

  2. Disconnect the M1 MAF meter connector.

  1. Disconnect the E4 ECM connector.

  1. Measure the resistance.

    Standard resistance (Check for open):
    Tester Connections
    		Specified Conditions
    VG (M1-3) - VG (E4-30)
    		Below 1 Ω
    E2G (M1-2) - E2G (E4-29)
    		Below 1 Ω
    Standard resistance (Check for short):
    Tester Connections
    		Specified Conditions
    VG (M1-3) or VG (E4-30) - Body ground
    		10 kΩ or higher

  1. Reconnect the MAF meter connector.

  1. Reconnect the ECM connector.



NGnext
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
next down
REPLACE MASS AIR FLOW METER