Page 353 of 5135
A76863
B±Y
Battery FL MAINEngine Room R/B No. 4
G EFI Relay
A6
Mass Air Flow MeterMREL
B±G 4B 1
W±BB±W 53
2
1
32
E128
E9ECM
EFI No. 1
EC 4A 1
Engine Room
J/B No. 4 1A 1
B±G 1 2
EFI 1
Engine Room
R/B No. 1 and
Engine Room
J/B No.14
4
44
4
4
2
1 W±B
B±R
B±RGR
GRIE1 2
EVG 24
E12VG
L±Y 1
3
2 EA112
± DIAGNOSTICSSFI SYSTEM (1AZ±FE)
05±187
AVENSIS REPAIR MANUAL (RM1018E)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the hand±held tester. Freeze frame data records the engine conditions when
a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running
or stopped, the engine was warmed up or not, the air±fuel ratio was lean or rich, etc. at the time of the mal-
function.
Page 354 of 5135

A54396
+B (+)
Wire Harness Side
Mass Air Flow Meter ConnectorA6
05±188
±
DIAGNOSTICS SFI SYSTEM(1AZ±FE)
AVENSIS REPAIR MANUAL (RM1018E)
When using hand±held tester:
1READ VALUE OF HAND±HELD TESTER(MASS AIR FLOW RATE)
(a)Connect the hand±held tester to the DLC3.
(b)Start the engine.
(c)Push the hand±held tester main switch ON.
(d)Select the item ºDIAGNOSIS / OBD/MOBD / DATA LIST / ALL / MAFº and read its value displayed on the hand±held tester.
Result:
Air flow rate (gm/s)Proceed to
0.0A
271.0 or moreB
1 Mass Air Flow Rate 270.0 or more (*1)C
*1: The value must be changed when the throttle valve is opened or closed.
BGo to step 6
CCHECK FOR INTERMITTENT PROBLEMS(See page 05±149)
A
2 INSPECT MASS AIR FLOW METER(POWER SOURCE)
(a) Turn the ignition switch ON.
(b) Disconnect the mass air flow meter connector.
(c) Measure the voltage between the terminal of the wire har- ness side connector and the body ground.
Standard:
Symbols (Terminal No.)Specified condition
+B (A6±1) ± Body ground9 to 14 V
NG Go to step 5
OK
Page 355 of 5135

A18294
VG (+)EVG (±)
E12
ECM Connector
A54396
VG
Wire Harness Side
Mass Air Flow Meter ConnectorE2G
A6
A65745
VG
EVG
E12
ECM Connector
±
DIAGNOSTICS SFI SYSTEM(1AZ±FE)
05±189
AVENSIS REPAIR MANUAL (RM1018E)
3INSPECT ECM(VG VOLTAGE)
(a)Start the engine.
(b)Measure the voltage between the terminals of the E12
ECM connector.
HINT:
The shift position should be P or N and the A/C switch should
be turned OFF. Standard:
Symbols (Terminal No.)ConditionSpecified condition
VG (E12±24) ±
EVG (E12±32)Engine is idling0.5 to 3.0 V
OKCHECK AND REPLACE ECM(See page 01±32)
NG
4 CHECK HARNESS AND CONNECTOR(MASS AIR FLOW METER ± ECM)
(a) Disconnect the mass air flow meter connector.
(b) Disconnect the E12 ECM connector.
(c) Check for continuity between the wire harness side con- nectors.
Standard (Check for open):
Symbols (Terminal No.)Specified condition
VG (A6±3) ± VG (E12±24)ContinuityE2G (A6±2) ± EVG (E12±32)Continuity
Standard (Check for short):
Symbols (Terminal No.)Specified condition
VG (A6±3) or VG (E12±24) ± Body groundNo continuity
NG REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
REPLACE MASS AIR FLOW METER
Page 356 of 5135

A66053
Engine Room R/B No.4EFI Relay
A79066
Engine Room R/B No.4EFI No.1 Fuse
1
2
A54396Mass Air Flow Meter Connector
Wire Harness Side
+B
A6
A18294
EVG
ECM Connector E12
05±190
±
DIAGNOSTICS SFI SYSTEM(1AZ±FE)
AVENSIS REPAIR MANUAL (RM1018E)
5CHECK HARNESS AND CONNECTOR(MASS AIR FLOW METER ± EFI RELAY)
(a)Remove the EFI relay from the engine room R/B No.4.
(b)Remove the EFI No.1 fuse from the engine room R/B No.4.
(c)Disconnect the mass air flow meter connector.
(d)Check for continuity between the wire harness side con- nectors.
Standard (Check for open):
Symbols (Terminal No.)Specified condition
EFI relay (3) ± EFI No.1 fuse (1)ContinuityEFI No.1 fuse (2) ± +B (A6±1)Continuity
Standard (Check for short):
Symbols (Terminal No.)Specified condition
EFI relay (3) or EFI No.1 fuse (1) ± Body groundNocontinuityEFI No.1 fuse (2) or +B (A6±1) ± Body groundNo continuity
NOTICE:
Do not insert the tester leads hard in the procedure (c), the
holder may be damaged.
NGREPAIR OR REPLACE HARNESS OR CONNECTOR
OK
CHECK FOR ECM POWER SOURCE CIRCUIT (See page 05±257)
6 INSPECT ECM(SENSOR GROUND)
(a) Check for continuity between the terminal of the E12 ECM connector and the body ground.
Standard:
Symbols (Terminal No.)Specified condition
EVG (E12±32) ± Body groundContinuity
NG CHECK AND REPLACE ECM (See page 01±32)
OK
Page 357 of 5135

A54396
VG
Wire Harness Side
Mass Air Flow Meter ConnectorE2G
A6
A65745
VG
EVG
E12
ECM Connector
A18294
VG (+)EVG (±)
E12
ECM Connector
±
DIAGNOSTICS SFI SYSTEM(1AZ±FE)
05±191
AVENSIS REPAIR MANUAL (RM1018E)
7CHECK HARNESS AND CONNECTOR(MASS AIR FLOW METER ± ECM)
(a)Disconnect the mass air flow meter connector.
(b)Disconnect the E12 ECM connector.
(c)Check for continuity between the wire harness side con-
nectors.
Standard (Check for open):
Symbols (Terminal No.)Specified condition
VG (A6±3) ± VG (E12±24)ContinuityE2G (A6±2) ± EVG (E12±32)Continuity
Standard (Check for short):
Symbols (Terminal No.)Specified condition
VG (A6±3)or VG (E12±24) ± Body groundNo continuity
NGREPAIR OR REPLACE HARNESS OR CONNECTOR
OK
REPLACE MASS AIR FLOW METER
When not using hand±held tester:
1INSPECT ECM(VG VOLTAGE)
(a)Start the engine.
(b)Measure the voltage between the terminals of the E12 ECM connector.
HINT:
The shift position should be P or N and the A/C switch should
be turned OFF. Standard:
Symbols (Terminal No.)ConditionSpecified condition
VG (E12±24) ±
EVG (E12±32)Engine is idling0.5 to 3.0 V
OKCHECK AND REPLACE ECM(See page 01±32)
NG
Page 358 of 5135

A54396
+B (+) Wire Harness Side
Mass Air Flow Meter ConnectorA6
A54396
VG Wire Harness Side
Mass Air Flow Meter ConnectorE2G A6
A65745
VGEVG
E12
ECM Connector
05±192
± DIAGNOSTICSSFI SYSTEM (1AZ±FE)
AVENSIS REPAIR MANUAL (RM1018E)
2 INSPECT MASS AIR FLOW METER(POWER SOURCE)
(a) Turn the ignition switch ON.
(b) Disconnect the mass air flow meter connector.
(c) Measure the voltage between the terminal of the wire har-
ness side connector and the body ground.
Standard:
Symbols (Terminal No.)Specified condition
+B (A6±1) ± Body ground9 to 14 V
NG Go to step 4
OK
3 CHECK HARNESS AND CONNECTOR(MASS AIR FLOW METER ± ECM)
(a) Disconnect the mass air flow meter connector.
(b) Disconnect the E12 ECM connector.
(c) Check for continuity between the wire harness side con-
nectors.
Standard (Check for open):
Symbols (Terminal No.)Specified condition
VG (A6±3) ± VG (E12±24)ContinuityE2G (A6±2) ± EVG (E12±32)Continuity
Standard (Check for short):
Symbols (Terminal No.)Specified condition
VG (A6±3) or VG (E12±24) ± Body groundNo continuity
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
REPLACE MASS AIR FLOW METER
Page 359 of 5135

A66053
Engine Room R/B No.4EFI Relay
A79066
Engine Room R/B No.4EFI No.1 Fuse
1
2
A54396Mass Air Flow Meter Connector
Wire Harness Side
+B
A6
±
DIAGNOSTICS SFI SYSTEM(1AZ±FE)
05±193
AVENSIS REPAIR MANUAL (RM1018E)
4CHECK HARNESS AND CONNECTOR(MASS AIR FLOW METER ± EFI RELAY)
(a)Remove the EFI relay from the engine room R/B No.4.
(b)Remove the EFI No.1 fuse from the engine room R/B
No.4.
(c)Disconnect the mass air flow meter connector.
(d)Check for continuity between the wire harness side con- nectors.
Standard (Check for open):
Symbols (Terminal No.)Specified condition
EFI relay (3) ± EFI No.1 fuse (1)ContinuityEFI No.1 fuse (2) ± +B (A6±1)Continuity
Standard (Check for short):
Symbols (Terminal No.)Specified condition
EFI relay (3) or EFI No.1 fuse (1) ± Body groundNocontinuityEFI No.1 fuse (2) or +B (A6±1) ± Body groundNo continuity
NOTICE:
Do not insert the tester leads hard in the procedure (c), the
holder may be damaged.
NGREPAIR OR REPLACE HARNESS OR CONNECTOR
OK
CHECK FOR ECM POWER SOURCE CIRCUIT (See page 05±257)
Page 360 of 5135

B62793
Reference (Bank 1 Sensor 1 System Drawing)A/F Sensor
A/F Relay
Heater
Sensor A1A+ HA1A
Duty
Control
ECM
From
Battery A/F Fuse
A1A±
MREL
05±182
±
DIAGNOSTICS SFI SYSTEM(1AZ±FE)
AVENSIS REPAIR MANUAL (RM1018E)
DTCP0031/21OXYGEN (A/F) SENSOR HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1)
DTCP0032/21OXYGEN (A/F) SENSOR HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 1)
DTCP0051/28OXYGEN (A/F) SENSOR HEATER CONTROL CIRCUIT LOW (BANK 2 SENSOR 1)
DTCP0052/28OXYGEN (A/F) SENSOR HEATER CONTROL CIRCUIT HIGH (BANK 2 SENSOR 1)
CIRCUIT DESCRIPTION
Refer to DTC P2237/21 on page 05±248.
HINT:
These DTCs are related to the air fuel raito (A/F) sensor, although the caption is the heated oxygen
sensor.
The ECM provides a pulse width modulated control circuit to adjust curre\
nt through the heater. The
heated oxygen sensor heater circuit uses a relay on the B+ side of the c\
ircuit.
DTC No.DTC Detection ConditionTrouble Area
P0031/21
P0051/28Heated current is 0.8 A or less when heater operates
(1 trip detection logic)Open or short in heater circuit of A/F sensor
A/F sensor heater
P0032/21
P0052/28When the heater operates, heated current exceeds 19.7 A
(1 trip detection logic)A/F relay
ECM
HINT:
Bank 1 refers to the bank that includes cylinder No.1.
Bank 2 refers to the bank that does not include cylinder No.1.
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.
05C6T±01