P0103

4GR-FSE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0102, P0103: Mass or Volume Air Flow Circuit Low Input

DESCRIPTION

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

The ECM uses this information to determine the fuel injection time and to provide an 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 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.









HINT
When any of these DTCs are set, check the air-flow rate by entering the following menus on Techstream: Powertrain / Engine / Data List / All Data / MAF.





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:

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

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

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS

P0102





P0103





COMPONENT OPERATING RANGE





CONFIRMATION DRIVING PATTERN





1. Connect the Techstream to the DLC3.

2. Turn the engine switch on (IG) and turn the Techstream on.

3. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation) Reading and Clearing Diagnostic Trouble Codes.

4. Turn the engine switch off and wait for at least 30 seconds.

5. Turn the engine switch on (IG) 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 / 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 / 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 / Utility / All Readiness.

14. Input the DTC: P0102 or P0103.

15. Check the DTC judgment result.





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 [E] again.

16. If no pending DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

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

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

HINT
Read freeze frame data using 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 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 Freeze Frame Data.

PROCEDURE

1. READ DTC OUTPUT (DTC P0102 OR P0103)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG) (do not run the engine).

(c) Turn the Techstream on.

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

(e) Read the DTCs.

Result:





B -- CHECK HARNESS AND CONNECTOR (SENSOR GROUND)
A -- Continue to next step.

2. INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE)

(a) Disconnect the E29 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:





(d) Reconnect the MAF meter connector.

NG -- CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - INTEGRATION RELAY)
OK -- Continue to next step.

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

(a) Disconnect the E29 MAF meter connector.

(b) Disconnect the E5 ECM connector.

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

Standard resistance (Check for open):





Standard resistance (Check for short):





(d) Reconnect the MAF meter connector.

(e) Reconnect the ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

4. INSPECT MASS AIR FLOW METER

(a) Perform On-vehicle Inspection Testing and Inspection.

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

(1) Connect the Techstream to the DLC3.

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

(3) Turn the Techstream on.

(4) Start the engine.

(5) Enter the following menus: Powertrain / Engine / Data List / All Data / MAF.

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

OK:

The reading changes.

NG -- REPLACE MASS AIR FLOW METER Removal

OK -- REPLACE ECM Removal

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

(a) Disconnect the E29 MAF meter connector.

(b) Remove the integration relay from the engine room R/B No. 2.

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

Standard resistance (Check for open):





Standard resistance (Check for short):





(d) Reconnect the MAF meter connector.

(e) Reinstall the integration relay.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- CHECK ECM POWER SOURCE CIRCUIT ECM Power Source Circuit

6. CHECK HARNESS AND CONNECTOR (SENSOR GROUND)

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

Standard resistance:





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

OK -- REPLACE MASS AIR FLOW METER Removal

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

(a) Disconnect the E29 MAF meter connector.

(b) Disconnect the E5 ECM connector.

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

Standard resistance:





(d) Reconnect the MAF meter connector.

(e) Reconnect the ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Removal