ES–90 3MZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM

DTC P0100 Mass or Volume Air Flow Circuit

DTC P0102 Mass or Volume Air Flow Circuit Low Input

DTC P0103 Mass or Volume Air Flow Circuit High Input

DESCRIPTION
The Mass Air Flow (MAF) meter measures the amount of air flowing through the throttle valve. The ECM
uses this information to determine the fuel injection time and provide a proper air fuel ratio. Inside the
MAF meter, there is a heated platinum wire exposed to the flow of intake air.
By applying a specific current to the wire, the ECM heats this wire to a given temperature. The flow of
ES incoming air cools the wire and an internal thermistor, changing 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 air flow through the sensor. The ECM interprets this voltage as the intake air
amount.
The circuit is constructed so that the platinum hot wire and temperature sensor provide a bridge circuit,
with the power transistor controlled so that the potential of A and B remains equal to maintain the set
temperature.

Temperature Sensor
(Thermistor) +B

Power Transistor

Platinum Hot Wire (Heater)

A B
Output Voltage

Temperature Sensor (Thermistor) Platinum Hot Wire (Heater)

A094565E03

DTC No. DTC Detection Condition Trouble Area

• Open or short in MAF meter circuit
When MAF meter circuit has an open or a short for
P0100 • MAF meter
more than 3 seconds under 4,000 rpm engine speed
• ECM
• Open or short in MAF meter circuit
When MAF meter circuit has an open for more than 3
P0102 • MAF meter
seconds under 4,000 rpm engine speed
• ECM
• Open or short in MAF meter circuit
When MAF meter circuit has a short for more than 3
P0103 • MAF meter
seconds under 4,000 rpm engine speed
• ECM

HINT:
After confirming DTC P0100, P0102 or P0103, use the intelligent tester or the OBD II scan tool to confirm
the MAF ratio from the ALL menu (to reach the ALL menu: DIAGNOSIS / ENHANCED OBD II / DATA
LIST / ALL).
Air Flow Value (gm/s) Malfunction
• Open in MAF meter power source circuit
Approx. 0.0
• Open or short in VG circuit
271.0 or more • Open in E2G circuit
 3MZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM ES–91

MONITOR DESCRIPTION
If there is a defect in the sensor, or an open or short circuit, the voltage level will deviate from the normal
operating range. The ECM interprets this deviation as a defect in the MAF meter and sets a DTC.
Example:
The sensor voltage output is less than 0.2 V or more than 4.9 V and either condition continues for more
than 3 seconds.

MONITOR STRATEGY
P0100: MAF Meter Range Check (Chattering)
Related DTCs P0102: MAF Meter Range Check (Low voltage)
P0103: MAF Meter Range Check (High voltage)
Required sensors / components (Main) MAF meter
Required sensors / components (Related) Crankshaft position sensor ES
Frequency of operation Continuous
Duration 3 seconds
Immediate: Engine RPM is less than 4,000 rpm
MIL operation
2 driving cycles: Engine RPM is 4,000 rpm or more
Sequence operation None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not present None

TYPICAL MALFUNCTION THRESHOLDS

P0100:
MAF meter voltage Less than 0.2 V, or more than 4.9 V

P0102:
MAF meter voltage Less than 0.2 V

P0103:
MAF meter voltage More than 4.9 V

COMPONENT OPERATING RANGE

Mass air flow meter voltage Between 0.4 V and 2.2 V
 ES–92 3MZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM

WIRING DIAGRAM

LG A J10
J/C
ECM
A 12 8
Y LG
IA2 E5 MREL
Fusible
Link LG
Block
7
2 2 Engine
2 M1
Room
Mass Air Flow Meter
EFI 1 5 R/B
ES No. 1 EFI B-R +B 30
VG R
MAIN 1 E8 VG
1 Relay 3
7A 1 2 3 E2G L-W
29
E8 E2G
EB1 1 2
2 2

GR
W
R
7
W-B
2
E Fusible
EFI Link
J8
FL MAIN No. 2 Block
J/C
E 1

A
J6
J/C R

Battery
IH

A082522E01

HINT:
Read freeze frame data using the intelligent tester or the OBD II scan tool. 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 running or stopped, 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.
 3MZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM ES–93

1 READ VALUE OF INTELLIGENT TESTER OR OBD II SCAN TOOL (MASS AIR FLOW RATE)

(a) Connect the intelligent tester or the OBD II scan tool to

the DLC3.
(b) Start the engine.
(c) Push the intelligent tester or the OBD II scan tool main
switch ON.
(d) On the intelligent tester or the OBD II scan tool, enter the
following menus: DIAGNOSIS / ENHANCED OBD II /
DATA LIST / ALL / MAF. Read the values.
Result
Air Flow Rate (gm/s) Proceed to ES
0.0 A
271.0 or more B
MAF rate greater than 1 but less than 270.0* C

HINT:
*: The value must change when the throttle valve is
opened or closed.
B Go to step 6

C CHECK FOR INTERMITTENT PROBLEMS

2 INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE)

(a) Turn the ignition switch ON.

Wire Harness Side: (b) Disconnect the M1 MAF meter connector.
(c) Measure the voltage of the wire harness side connector.
Standard voltage
+B (+)
Tester Connection Specified Condition
M1-1 (+B) - Body ground 9 to 14 V

M1 MAF Meter Connector

NG Go to step 5
A054396E28

OK
 ES–94 3MZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM

3 INSPECT ECM (VG VOLTAGE)

(a) Start the engine.

(b) Measure the voltage of the E8 ECM connector.
E8 HINT:
The shift position should be P or N and the A/C switch
should be turned OFF.
Standard voltage
Tester Connection Condition Specified Condition

VG (+) E2G (-) E8-30 (VG) -

Engine is idling 0.5 to 3.0 V
ECM Connector E8-29 (E2G)

ES A076903E59

OK REPLACE ECM

NG

4 CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

(a) Disconnect the M1 MAF meter connector.

Wire Harness Side: (b) Disconnect the E8 ECM connector.
(c) Measure the resistance of the wire harness side
M1 MAF Meter
connectors.
Standard resistance
Tester Connection Specified Condition
M1-3 (VG) - E8-30 (VG)
Below 1 Ω
M1-2 (E2G) - E8-29 (E2G)

E2G VG M1-3 (VG) or E8-30 (VG) - Body ground 10 kΩ or higher

E8 ECM (d) Reconnect the MAF meter connector and ECM

connector.
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR

E2G
ECM Connector
VG
A085482E09

OK

REPLACE MASS AIR FLOW METER

 3MZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM ES–95

5 CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - EFI MAIN RELAY)

(a) Check the EFI No. 2 fuse.

Wire Harness Side: (1) Remove the EFI No. 2 fuse the fusible link block.
(2) Measure the resistance of the EFI No. 2 fuse.
Mass Air Flow Meter Connector Standard:
Below 1 Ω
(3) Reinstall the EFI No. 2 fuse.
M1 (b) Disconnect the M1 MAF meter connector.
(c) Remove the EFI MAIN relay from the engine room R/B.
+B (+) (d) Measure the resistance of the wire harness side
Front View connectors.
Engine Room R/B and Standard resistance
ES
Fusible Link Block: Tester Connection Specified Condition
M1-1 (+B) - EFI MAIN relay terminal 3 Below 1 Ω
M1-1 (+B) or EFI MAIN relay terminal 3 - Body ground 10 kΩ or higher

(e) Reconnect the MAF meter connector.

EFI MAIN (f) Reinstall the EFI MAIN relay.
Relay
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
EFI No. 2
A124290E01

OK

INSPECT ECM POWER SOURCE CIRCUIT

6 INSPECT ECM (SENSOR GROUND)

(a) Measure the resistance of the ECM connector.

E2G
Standard resistance
Tester Connection Specified Condition
E8-29 (E2G) - Body ground Below 1 Ω

NG REPLACE ECM

E8 ECM
A076903E68

OK
 ES–96 3MZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM

7 CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

(a) Disconnect the M1 MAF meter connector.

Wire Harness Side: (b) Disconnect the E8 ECM connector.
(c) Measure the resistance of between the wire harness
M1 MAF Meter
side connectors.
Standard resistance
Tester Connection Specified Condition
M1-3 (VG) - E8-30 (VG)
Below 1 Ω
M1-2 (E2G) - E8-29 (E2G)

E2G VG M1-3 (VG) or E8-30 (VG) - Body ground 10 kΩor higher

ES E8 ECM (d) Reconnect the MAF meter connector and ECM

connector.
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR

E2G
ECM Connector
VG
A085482E09

OK

REPLACE MASS AIR FLOW METER