ECD SYSTEM(w/o Glow Plug Controller), Diagnostic DTC:P0102 and P0103

DTC Code	DTC Name
P0102	Mass Air Flow Circuit Low
P0103	Mass Air Flow Circuit High

DESCRIPTION

The Mass Air Flow (MAF) 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) detect the intake air temperature.

There is little variation in the output from the mass air flow meter, as it is hardly affected by the resistance of the wire harness.

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.


DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory
P0102	Mass Air Flow Circuit Low	Generated pulse period is 50 μsec. or less (MAF value is extremely high). (1 trip detection logic)	Open or short in Mass Air Flow (MAF) meter circuit Mass air flow meter ECM	Comes on	DTC stored
P0103	Mass Air Flow Circuit High	Generated pulse period is 2100 μsec. or more (MAF value is extremely low). (1 trip detection logic)	Open or short in Mass Air Flow (MAF) meter circuit Mass air flow meter ECM	Comes on	DTC stored

Table 1. DTC Detection Drive Pattern
DTC No.	DTC Detection Drive Pattern
P0102	Engine speed between 750 to 2500 rpm
P0103	Engine speed between 750 to 2500 rpm

Table 2. Related Data List
DTC No.	Data List
P0102	MAF
P0103	MAF

Tip:

If DTC P0102 is stored, the following symptoms may appear (as the ECU mistakenly determines that there is less air than the actual intake air amount, EGR is decreased to match the target EGR):
- Combustion noise increases
If DTC P0103 is stored, the following symptoms may appear (as the ECU mistakenly determines that there is more air than the actual intake air amount, EGR is increased to match the target EGR):
- Misfire
- White smoke
- Black smoke

WIRING DIAGRAM

CAUTION / NOTICE / HINT

Note:

When replacing the ECM, perform ECM Initialization and Registration.
Click here Click here
Inspect the fuses for circuits related to this system before performing the following procedure.

Tip:

When the ECM must be replaced, before replacing the ECM, perform the "Learning Values Save" function using the GTS. Then after installing a new ECM, perform all of the initialization and registration procedures for the "Learning Values Write" function by following the instructions shown on the GTS display.
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.

PROCEDURE

CHECK TERMINAL VOLTAGE (POWER SOURCE OF MASS AIR FLOW METER)

*a	Front view of wire harness connector (to Mass Air Flow Meter)

Disconnect the mass air flow meter connector.

Turn the ignition switch to ON.

Measure the voltage according to the value(s) in the table below.

Standard Voltage


Tester Connection	Condition	Specified Condition
B2-3 (+B) - Body ground	Ignition switch ON	11 to 14 V

Result


Proceed to
OK
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (EFI-MAIN RELAY - MASS AIR FLOW METER)Click here

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


Tester Connection	Condition	Specified Condition
B2-1 (VG) - A101-11 (VG)	Always	Below 1 Ω
B2-2 (E2G) - A101-12 (EVG)	Always	Below 1 Ω
B2-1 (VG) or A101-11 (VG) - Body ground	Always	10 kΩ or higher
B2-2 (E2G) or A101-12 (EVG) - Body ground	Always	10 kΩ or higher

Result


Proceed to
OK
NG

REPAIR OR REPLACE HARNESS OR CONNECTORClick here

REPLACE MASS AIR FLOW METER

Replace the mass air flow meter.
Click here

Result


Proceed to
NEXT

CHECK WHETHER DTC OUTPUT RECURS (DTC P0102 OR P0103)

Connect the GTS to the DLC3.
Turn the ignition switch to ON and turn the GTS on.
Clear the DTCs.

Powertrain > Engine and ECT > Clear DTCs
Start the engine and depress the accelerator pedal several times to vary the engine speed to between 750 and 2500 rpm.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

Read the DTCs.

Powertrain > Engine and ECT > Trouble Codes

Result


Result	Proceed to
DTC P0102 or P0103 is output	A
DTC is not output	B

END

REPLACE ECM

Replace the ECM.
Click here

Result


Proceed to
NEXT

CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

Connect the GTS to the DLC3.
Turn the ignition switch to ON and turn the GTS on.
Clear the DTCs.

Powertrain > Engine and ECT > Clear DTCs
Start the engine and depress the accelerator pedal several times to the engine speed between 750 to 2500 rpm.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Confirm that the DTC is not output again.

Powertrain > Engine and ECT > Trouble Codes

Result


Proceed to
NEXT

END

REPAIR OR REPLACE HARNESS OR CONNECTOR

Result


Proceed to
NEXT

CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIREDClick here

REPAIR OR REPLACE HARNESS OR CONNECTOR (EFI-MAIN RELAY - MASS AIR FLOW METER)

Result


Proceed to
NEXT

CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIREDClick here