DESCRIPTION
The mass air flow meter sub-assembly is a sensor that measures the intake air volume using the following built-in components:
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 is 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). |
| 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). |
| 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 |
All of the following conditions are met | - |
Battery voltage | 8 V or higher |
Engine switch | On (IG) |
Starter | Off |
TYPICAL MALFUNCTION THRESHOLDS
P0102 Mass air flow meter output frequency | Less than 0.1 kHz |
Mass air flow meter output frequency | Higher than 9.8 kHz |
CONFIRMATION DRIVING PATTERN
HINT:
Click here
Click here
HINT:
Techstream Display | Description |
---|---|
NORMAL |
|
ABNORMAL |
|
INCOMPLETE |
|
HINT:
The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
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 engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection | Condition | Specified Condition |
---|---|---|
C18-3 (5V) - C18-2 (E2G) | Engine switch on (IG) | 4.8 to 5.2 V |
C18-1 (FG) - C18-2 (E2G) | Engine switch on (IG) | 4.8 to 5.2 V |
NG | GO TO STEP 5 |
|
2. | INSPECT MASS AIR FLOW METER SUB-ASSEMBLY |
(a) Inspect the mass air flow meter sub-assembly.
Click here
|
3. | CLEAR DTC |
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Clear the DTC.
Powertrain > Engine > Clear DTCs(e) Turn the engine switch off and wait for at least 30 seconds.
|
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 |
---|---|---|
C18-3 (5V) - C32-90 (VC) | Always | Below 1 Ω |
C18-1 (FG) - C32-116 (VG) | Always | Below 1 Ω |
C18-2 (E2G) - C32-115 (E2G) | Always | Below 1 Ω |
C18-3 (5V) or C32-90 (VC) - Body ground and other terminals | Always | 10 kΩ or higher |
C18-1 (FG) or C32-116 (VG) - Body ground and other terminals | Always | 10 kΩ or higher |
C18-2 (E2G) or C32-115 (E2G) - Body ground and other terminals | Always | 10 kΩ or higher |
OK | REPLACE ECM |
NG | REPAIR OR REPLACE HARNESS OR CONNECTOR |