P0102
DTC P0102 MASS OR VOLUME AIR FLOW CIRCUIT LOW INPUTComponent Location:
COMPONENT LOCATION
GENERAL DESCRIPTION
The mass air flow sensor (MAF) is located between the air cleaner assembly and throttle body. The MAF uses a hot film type sensing element to measure the mass of intake air entering the engine. This hot film type air flow sensor consists of a hot film sensor, housing and metering ducts. Mass air flow rate is measured by detection of heat transfer from a hot film probe. The change in air flow rate causes change in the amount of heat being transferred from the hot film probe surface to the air. A large amount of intake air represents acceleration or high load condition while a small amount of intake air represent acceleration or idle. The mass of intake air should increase at acceleration and be stable during constant engine speed. The PCM uses this information to determine the injection duration and ignition timing for the desired air/fuel ratio.
DTC DESCRIPTION
If MAF output voltage is lower than threshold value, the PCM determines that a fault exists and a DTC is stored.
DTC Detecting Condition:
DTC DETECTING CONDITION
Specification:
SPECIFICATION
Schematic Diagram:
SCHEMATIC DIAGRAM
MONITOR SCANTOOL DATA
1. Connect scantool to Data Link Connector(DLC).
2. Engine "ON" & Warm up the engine to normal operating temperature.
3. Monitor the "MAFS VOLTAGE" parameter on scantool.
Specification : Voltage increases in response to racing (Refer to the table.)
4. Is the MAF sensor parameter displayed within specifications?
YES: Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "W/Harness Inspection" procedure.
TERMINAL & CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals.
Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination,deterioration, or damage.
3. Has a problem been found?
YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to " Power Circuit Inspection " procedure.
POWER CIRCUIT INSPECTION
1. Check Power Supply
1. Ignition "OFF"
2. Disconnect MAP sensor connector.
3. Ignition " ON " & Engine "OFF"
4. Measure voltage between terminal 4 of MAP sensor harness connector and chassis ground.
Specification : Approx. B+
5. Is the measured voltage within specifications?
YES: Go to "Check MAFS Power" as below.
NO:
- Check that Fuse is installed or blown off between control relay and MAF sensor.
- Check open in hareness between control relay and MAF sensor.
- Repair or replace as necessary and then, go to " Verification of Vehicle Repair" procedure.
2. Check MAFS Power
1. Ignition "OFF"
2. Disconnect MAF sensor connector.
3. Ignition "ON" & Engine "OFF"
4. Measure voltage between terminal 2 of MAF sensor harness connector and chassis ground.
Specification : Approx. 5 V
5. Is the measured voltage within specifications?
YES: Go to "Signal Circuit Inspection" procedure.
NO:
- Check open in harness between control relay and MAP sensor.
- Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
SIGNAL CIRCUIT INSPECTION
1. Check for short to ground in harness.
1. Ignition "OFF"
2. Disconnect MAFS sensor and PCM connector.
3. Measure resistance between terminal 1 of MAFS sensor harness connector and chassis ground.
Specification : Infinite
4. Is the measured resistance within specifications?
YES: Go to " Check for open in harness " as below.
NO:
- Check short to ground in signal harness.
- Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
2. Check for open in harness
1. Ignition "OFF"
2. Disconnect MAFS sensor and PCM connector.
3. Measure resistance between terminal 1 of MAFS sensor harness connector and terminal B15 of PCM harness connector.
Specification : Approx. below 1 Ohm
4. Is the measured resistance within specifications?
YES: Go to "Component Inspection" procedure.
NO:
- Check open in harness between MAFS connector and PCM connector.
- Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. Visual Inspection
1. Check the MAFS for contamination, deterioration, or damage.
2. Is the MAFS contaminated, deteriorated or damaged?
YES: Repair or replace as necessary and Go to "Verification of Vehicle Repair" procedure.
NO: Go to " Check MAFS" as below.
2. Check MAFS
1. Engine "ON"
2. Connect Scantool and select the "MAF SENSOR" parameter on the CURRENT DATA.
3. Monitor signal waveform of the "MAF SENSOR" on the Scantool.
Specification : MAF value is increased correspondently with TPS when pressing accelerator pedal.
4. Is the measured signal waveform of MAF sensor displaying correctly ?
YES: Go to "Check PCM" as below.
NO: Substitute with a known - good MAF and check for proper operation. If the problem is corrected, replace MAF and go to "Verification of Vehicle Repair" procedure.
3. Check PCM
1. Ignition "OFF"
2. Connect Scantool and Ignition "ON "
3. Select simulation function on scantool.
4. Simulate voltage at terminal 1 of MAF sensor signal connector.
5. Does the signal value of MAF sensor changes according to simulation voltage ?
YES: Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Substitute with a known - good PCM and check for proper operation.
If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all readiness test have been verified as "Complete"
5. Are any DTCs present ?
YES: Go to the applicable troubleshooting procedure.
NO: System is performing to specification at this time.