GR-FE EINE CONTROL SYSTEM SFI SYSTEM 95 DTC P000 Mass or Volume Air Flow Circuit DTC P00 Mass or Volume Air Flow Circuit Low Input DTC P003 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) Piatinum Hot Wire A Output Voltage Piatinum Hot Wire (Heater) A5747E0 DTC No. DTC Detection Conditions Trouble Areas P000 P00 P003 Open or short in Mass Air Flow (MAF) meter circuit for 3 seconds ( trip detection logic) Open in Mass Air Flow (MAF) meter circuit for 3 seconds ( trip detection logic) Short in Mass Air Flow (MAF) meter circuit for 3 seconds ( trip detection logic) Open or short in MAF meter circuit MAF meter ECM Open in MAF meter circuit Short in ground circuit MAF meter ECM Short in MAF meter circuit (+ circuit) MAF meter ECM
96 GR-FE EINE CONTROL SYSTEM SFI SYSTEM 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. 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 7.0 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 P000: Mass air flow meter range check (Fluctuating) P00: Mass air flow meter range check (Low voltage) P003: 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 P000: P00: P003: 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
GR-FE EINE CONTROL SYSTEM SFI SYSTEM 97 WIRI DIAGRAM Engine Room Relay lock EFI Relay Engine Room Relay lock EFI No. L 5 3 0 4 A L-W W- G-W L-W ECM EFI 30 A Engine Room Relay lock 3 30 R-Y R-W 9 EG C 33 A W- M Mass Air Flow Meter attery E 0 A G-W 8 E8 MREL A5906E0 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. READ VALUE USI INTELLIGENT TTER (MASS AIR FLOW RATE) Result Connect an intelligent tester to the DLC3. Start the engine. Turn the tester ON. Select the following menu items: DIAGNOSIS / ENHANCED OD II / DATA LIST / PRIMARY / MAF. (e) Read the values displayed on the tester. Mass Air Flow Rate (g/sec) Proceed to 0.0 A 7.0 or more
98 GR-FE EINE CONTROL SYSTEM SFI SYSTEM Mass Air Flow Rate (g/sec) etween.0 and 70.0 ( * ) Proceed to C * : 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) M + MAF Meter Connector Disconnect the M Mass Air Flow (MAF) meter connector. Turn the ignition switch ON. Measure the voltage between the terminal of the wire harness side connector and body ground. Standard Voltage 3 4 5 A0794E0 + (M-) - ody ground 9 to 4 V 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 Conditions (-30) - EG (-9) Engine idling 0.5 to 3.0 V (+) EG (-) REPLACE ECM A5970E03
GR-FE EINE CONTROL SYSTEM SFI SYSTEM 99 4 CHECK HARNS AND CONNECTOR (MASS AIR FLOW METER - ECM) M MAF Meter Connector EG (e) Disconnect the M MAF meter connector. Disconnect the ECM connector. Standard Resistance (Check for open) (M-3) - (-30) EG (M-) - EG (-9) Standard Resistance (Check for short) (M-3) or (-30) - ody ground Reconnect the ECM connector. elow Ω 0 kω or higher REPAIR OR REPLACE HARNS OR CONNECTOR EG A658E0 REPLACE MASS AIR FLOW METER
00 GR-FE EINE CONTROL SYSTEM SFI SYSTEM 5 CHECK HARNS AND CONNECTOR (MASS AIR FLOW METER - EFI RELAY) M MAF Meter Connector + (+) Engine Room R/: EFI No. Inspect the EFI NO. fuse. () Remove the EFI NO. fuse from the engine room relay block. () Check the EFI NO. fuse resistance. Standard Resistance: elow Ω (3) Reinstall the EFI NO. fuse. Disconnect the M MAF meter connector. Remove the EFI relay from the engine room relay block. Standard Resistance (Check for open) + (M-) - EFI relay (3) elow Ω Standard Resistance (Check for short) + (M-) or EFI relay (3) - ody ground 0 kω or higher EFI Relay A659E0 (e) (f) Reinstall the EFI relay. REPAIR OR REPLACE HARNS OR CONNECTOR CHECK ECM POWER SOURCE CIRCUIT 6 INSPECT ECM (SENSOR GROUND) Standard Resistance EG (-9) - ody ground elow Ω REPLACE ECM EG A5970E04
GR-FE EINE CONTROL SYSTEM SFI SYSTEM 0 7 CHECK HARNS AND CONNECTOR (MASS AIR FLOW METER - ECM) M MAF Meter Connector EG (e) Disconnect the M MAF meter connector. Disconnect the ECM connector. Standard Resistance (Check for open) (M-3) - (-30) EG (M-) - EG (-9) Standard Resistance (Check for short) (M-3) or (-30) - ody ground Reconnect the ECM connector. elow Ω 0 kω or higher REPAIR OR REPLACE HARNS OR CONNECTOR EG A658E0 REPLACE MASS AIR FLOW METER