DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
INSPECT MASS AIR FLOW METER (POWER SOURCE CIRCUIT)
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - INTEGRATION RELAY)
INSPECT INTEGRATION RELAY (EFI MAIN 2)
CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - ECM)
CHECK ECM POWER SOURCE CIRCUIT
REPAIR OR REPLACE HARNESS OR CONNECTOR
REPLACE INTEGRATION RELAY
REPLACE MASS AIR FLOW METER
CHECK WHETHER DTC OUTPUT RECURS
REPLACE ECM
CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED
DTC P0100 Mass Air Flow Circuit Malfunction
DESCRIPTION
The mass air flow meter consists of a platinum hot wire, a temperature sensor and a control circuit installed in a plastic housing. The temperature sensor (located in the intake air by-pass of the housing) detects the intake air temperature.
There is little variation in the output from the mass air flow meter, as the output voltage is converted into a periodic signal which minimizes the effect of wire harness resistance.
The internal circuit of the mass air flow meter contains a hot wire and cold wire. A voltage is output through a bridge circuit (refer to the illustration) indicating the cooling of the hot wire according to the intake air amount. This voltage is then converted into a periodic signal by the periodic signal conversion circuit and output to the ECM. The frequency varies between approximately 250 to 11000 Hz depending on the air flow rate. The ECM calculates the mass air flow rate based on this frequency.
P0100| DTC Detection Drive Pattern | DTC Detection Condition | Trouble Area |
| 3 seconds after engine is started | Mass air flow meter signal frequency is less than 850 Hz with the engine speed at 400 rpm or more for 3 seconds (1 trip detection logic). | Open or short in mass air flow meter circuit
Mass air flow meter
ECM
|
Related Data List| DTC No. | Data List |
| P0100 | MAF |
If DTC P0100 is stored, the following symptoms may appear (as the ECM mistakenly determines that there is less air than the actual intake air amount, EGR is decreased according to the target EGR):
WIRING DIAGRAM
INSPECTION PROCEDURE
Inspect the fuses of circuits related to this system before performing the following inspection procedure.
After replacing the ECM, the new ECM needs registration () and initialization ().
After replacing the fuel supply pump assembly, the ECM needs initialization ().
After replacing an injector assembly, the ECM needs registration ().
- Read freeze frame data using the GTS. Freeze frame data records 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, and other data from the time the malfunction occurred.
| 1.INSPECT MASS AIR FLOW METER (POWER SOURCE CIRCUIT) |
Disconnect the mass air flow meter connector.
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
| C50-3 (+B) - Body ground | Engine switch on (IG) | 11 to 14 V |
Text in Illustration| *a | Front view of wire harness connector
(to Mass Air Flow Meter) |
Reconnect the mass air flow meter connector.
| 2.CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM) |
Disconnect the mass air flow meter connector.
Disconnect the ECM connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
for LHD| Tester Connection | Condition | Specified Condition |
| C50-1 (FG) - C45-71 (VG) | Always | Below 1 Ω |
| C50-2 (E2G) - C45-94 (EVG) | Always | Below 1 Ω |
| C50-1 (FG) or C45-71 (VG) - Body ground | Always | 10 kΩ or higher |
- Standard Resistance:
for RHD| Tester Connection | Condition | Specified Condition |
| C50-1 (FG) - C46-71 (VG) | Always | Below 1 Ω |
| C50-2 (E2G) - C46-94 (EVG) | Always | Below 1 Ω |
| C50-1 (FG) or C46-71 (VG) - Body ground | Always | 10 kΩ or higher |
Reconnect the mass air flow meter connector.
Reconnect the ECM connector.
| 3.CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - INTEGRATION RELAY) |
Disconnect the mass air flow meter connector.
Remove the integration relay from the engine room relay block and junction block assembly.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
| Tester Connection | Condition | Specified Condition |
| C50-3 (+B) - 1A-4 | Always | Below 1 Ω |
| C50-3 (+B) or 1A-4 - Body ground | Always | 10 kΩ or higher |
| 4.INSPECT INTEGRATION RELAY (EFI MAIN 2) |
Inspect the integration relay (EFI MAIN 2) ().
| 5.CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - ECM) |
Remove the integration relay from the engine room relay block and junction block assembly.
Disconnect the ECM connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
for LHD| Tester Connection | Condition | Specified Condition |
| 1A-2 - A38-44 (MREL) | Always | Below 1 Ω |
| 1A-2 or A38-44 (MREL) - Body ground | Always | 10 kΩ or higher |
- Standard Resistance:
for RHD| Tester Connection | Condition | Specified Condition |
| 1A-2 - A52-44 (MREL) | Always | Below 1 Ω |
| 1A-2 or A52-44 (MREL) - Body ground | Always | 10 kΩ or higher |
| 6.CHECK ECM POWER SOURCE CIRCUIT |
Check the ECM power source circuit ().
| 7.REPAIR OR REPLACE HARNESS OR CONNECTOR |
Repair or replace the harness or connector.
| 8.REPLACE INTEGRATION RELAY |
Replace the integration relay (EFI MAIN 2).
| 9.REPLACE MASS AIR FLOW METER |
Replace the mass air flow meter ().
| 10.CHECK WHETHER DTC OUTPUT RECURS |
Connect the GTS to the DLC3.
Start the engine and wait for 3 seconds or more.
Enter the following menus: Engine and ECT / Trouble Codes.
Read the DTCs.
Result| Result | Proceed to |
| P0100 is output | A |
| No DTC is output | B |
| 12.CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED |
Connect the GTS to the DLC3.
Start the engine and wait for 3 seconds or more.
Enter the following menus: Engine and ECT / Trouble Codes.
Confirm that the DTC is not output again.
