94 TR-FE EINE CONTROL SYSTEM SFI SYSTEM DTC P0100 Mass or Volume Air Flow Circuit DTC P010 Mass or Volume Air Flow Circuit Low Input DTC P0103 Mass or Volume Air Flow Circuit High Input DCRIPTION 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. y 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 remain equal to maintain the predetermined temperature. 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. Temperature Sensor (Thermistor) + Power Transistor Temperature Sensor (Thermistor) Platinum Hot Wire A Output Voltage Platinum Hot Wire (Heater) A115747E03 DTC No. DTC Detection Conditions Trouble Areas P0100 P010 P0103 Mass Air Flow (MAF) meter voltage less than 0. V, or more than 4.9 V for 3 seconds Mass Air Flow (MAF) meter voltage less than 0. V for 3 seconds Mass Air Flow (MAF) meter more than 4.9 V for 3 seconds Open or short in MAF meter circuit MAF meter ECM Open or short in MAF meter circuit MAF meter ECM Open or short in MAF meter circuit MAF meter ECM When any of these DTCs are set, check the air-flow rate by selecting the following menu items on an intelligent tester: DIAGNOSIS / ENHANCED OD II / DATA LIST / PRIMARY / MAF.
TR-FE EINE CONTROL SYSTEM SFI SYSTEM 95 Mass Air Flow Rate (g/sec) Malfunctions Open in Mass Air Flow (MAF) meter power source circuit Approximately 0.0 Open or short in circuit 71.0 or more Open in E circuit MONITOR DCRIPTION 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 voltage output remains less than 0. V, or more than 4.9 V, for more than 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 Related DTCs Required Sensors/Components (Main) Required Sensors/Components (Related) Frequency of Operation Duration MIL Operation Sequence of Operation P0100: Mass air flow meter range check (Fluctuating) P010: Mass air flow meter range check (Low voltage) P0103: Mass air flow meter range check (High voltage) MAF meter Crankshaft position sensor Continuous 3 seconds Immediate: Engine RPM less than 4,000 rpm driving cycles: Engine RPM 4,000 rpm or more None TYPICAL ENALI CONDITIONS Monitor runs whenever following DTCs not present None TYPICAL MALFUNCTION THRHOLDS P0100: P010: P0103: Less than 0. V, or more than 4.9 V Less than 0. V More than 4.9 V COMPONENT OPERATI RAE etween 0.4 V and. V
96 TR-FE EINE CONTROL SYSTEM SFI SYSTEM WIRI DIAGRAM Engine Room R/ Engine Room R/ and J/ EFI Relay EFI No. L 5 3 1 1 10 14 A L-W W- L-W A 30 1 Mass Air Flow Meter 3 R-Y 8 ECM 1 EFI Engine Room R/ R-W 30 EG 1 C A 33 W- G-W 10 IA1 G-W 8 E8 MREL attery E A11737E01 Read freeze frame data using an intelligent tester. Freeze frame data record 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. 1 READ DATA LIST (MASS AIR FLOW RATE) Connect an intelligent tester to the DLC3. Start the engine. Turn the tester ON. (d) Select the following menu items: DIAGNOSIS / ENHANCED OD II / DATA LIST / PRIMARY / MAF.
TR-FE EINE CONTROL SYSTEM SFI SYSTEM 97 (e) Read the values displayed on the tester. Result Mass Air Flow Rate (g/sec) Proceed To 0.0 A 71.0 or more etween 1.0 and 70.0 ( * 1) C * 1: The value must be changed when the throttle valve is open or closed. C Go to step 6 CHECK FOR INTERMITTENT PROLEMS A INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE) + (+) MAF Meter Connector Disconnect the Mass Air Flow (MAF) meter connector. Turn the ignition switch to ON. Measure the voltage between the terminal of the wire harness side connector and body ground. Standard Voltage + (-1) - ody ground 9 to 14 V A0543961 (d) Reconnect the MAF meter connector. Go to step 5 3 INSPECT ECM ( VOLTAGE) Start the engine. Measure the voltage between the terminals of the ECM connector. The transmission gear selector lever should be in the P or N position and the A/C switch should be turned OFF. Standard Voltage EG A13893E03 Engine Conditions (-8) - EG (-30) Engine idling 0.5 to 3.0 V REPLACE ECM
98 TR-FE EINE CONTROL SYSTEM SFI SYSTEM 4 CHECK HARNS AND CONNECTOR (MASS AIR FLOW METER - ECM) MAF Meter Connector Disconnect the MAF meter connector. Disconnect the ECM connector. Standard Resistance (Check for open) (-3) - (-8) EG (-) - EG (-30) EG Standard Resistance (Check for short) (-3) or (-8) - ody ground 10 kω or higher (d) Reconnect the MAF meter connector. (e) Reconnect the ECM connector. REPAIR OR REPLACE HARNS OR CONNECTOR EG A13978E01 REPLACE MASS AIR FLOW METER
TR-FE EINE CONTROL SYSTEM SFI SYSTEM 99 5 CHECK HARNS AND CONNECTOR (MASS AIR FLOW METER - EFI RELAY) Engine Room R/: EFI No. Fuse EFI Relay MAF Meter Connector (d) Inspect the EFI No. fuse. (1) Remove the EFI No. fuse from the engine room R/. () Check the EFI No. fuse resistance. Standard Resistance: elow 1Ω (3) Reinstall the EFI No. fuse. Remove the EFI relay from the engine room R/. Disconnect the MAF meter connector. Standard Resistance (Check for open) + (-1) - EFI relay (3) Standard Resistance (Check for short) + A14186E01 (e) (f) + (-1) or EFI relay (3) - ody ground Reconnect the MAF meter connector. Reinstall the EFI relay. 10 kω or higher REPAIR OR REPLACE HARNS OR CONNECTOR INSPECT ECM POWER SOURCE CIRCUIT 6 INSPECT ECM (SENSOR GROUND) Standard Resistance EG (-30) - ody ground REPLACE ECM EG A13893E04
100 TR-FE EINE CONTROL SYSTEM SFI SYSTEM 7 CHECK HARNS AND CONNECTOR (MASS AIR FLOW METER - ECM) MAF Meter Connector Disconnect the MAF meter connector. Disconnect the ECM connector. Standard Resistance (Check for open) (-3) - (-8) EG (-) - EG (-30) EG Standard Resistance (Check for short) (d) (e) (-3) or (-8) - ody ground Reconnect the MAF meter connector. Reconnect the ECM connector. 10 kω or higher REPAIR OR REPLACE HARNS OR CONNECTOR EG A13978E01 REPLACE MASS AIR FLOW METER