Page 2785 of 4770
± DIAGNOSTICSENGINE (1MZ±FE)
DI±365
600 Author: Date:
3 Check harness and connector between ECM and stop light switch
(See page IN±31).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±31).
Page 2786 of 4770
S05470
Battery FL
MAIN B±G
F4
F61 1
18
B Fusible
Link
BlockEngine Room J/B No.2
2A2JB±YECM
BATT EFI
E71 DI±366
± DIAGNOSTICSENGINE (1MZ±FE)
601 Author: Date:
DTC P1600 ECM BATT Malfunction
CIRCUIT DESCRIPTION
Battery positive voltage is supplied to terminal BATT of the ECM even when the ignition switch is OFF for
use by the DTC memory and air±fuel ratio adaptive control value memory, etc.
DTC No.DTC Detecting ConditionTrouble Area
P1600Open in back up power source circuitOpen in back up power source circuit
ECM
HINT:
If DTC P1600 appear, the ECM does not store another DTC.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because free frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
DI089±06
Page 2787 of 4770
A02038
LOCK
BATT (+)
S04162
Engine Room J/B
EFI Fuse
± DIAGNOSTICSENGINE (1MZ±FE)
DI±367
602 Author: Date:
1 Check voltage between terminal BATT of ECM connector and body ground.
PREPARATION:
Remove the glove compartment (See page SF±73).
CHECK:
Measure voltage between terminal BATT of the ECM connector
and body ground.
OK:
Voltage: 9 ~ 14 V
OK Check and replace ECM (See page IN±31).
NG
2 Check EFI fuse.
PREPARATION:
Remove the EFI fuse from the engine room J/B.
CHECK:
Check continuity of EFI fuse.
OK:
Continuity
NG Check for short in all harness and components
connected to EFI fuse.
OK
Check and repair harness or connector be-
tween battery and EFI fuse, and EFI fuse and
ECM (See page IN±31).
Page 2788 of 4770

DI±368
± DIAGNOSTICSENGINE (1MZ±FE)
603 Author: Date:
DTC P1780 Park/Neutral Position Switch Malfunction
CIRCUIT DESCRIPTION
The park/neutral position switch go on when the shift lever is in the N or P shift position. When it goes on
terminal NSW of the ECM is grounded to body ground via the starter relay, thus the terminal NSW voltage
becomes 0V. When the shift lever is in the D, 2, L or R position, the park/neutral position switch goes off,
so the voltage of ECM. Terminal NSW becomes battery voltage, the voltage of the ECM internal power
source. If the shift lever is moved from the N position to the D position, this signal is used for air±fuel ratio
correction and for idle speed control (estimated control), etc.
DTC No.DTC Detecting ConditionTrouble Area
2 or more switches are ON simultaneously for ºNº, º2º, ºLº and
ºRº positions
(2 trip detection logic)
Sh t i k/ t l iti it h i it
P1780When driving under conditions (a) and (b) for 30 sec. or more
the park/neutral position switch is ON (N position):
(2 trip detection logic)
(a) Vehicle speed: 70 km/h (44 mph) or more
(b) Engine speed: 1,500 NE and 2,500 rpmShort in park/neutral position switch circuit
Park/neutral position switch
ECM
HINT:
After confirming DTC P1780, use the TOYOTA hand±held tester to confirm the PNP switch signal from
ºCURRENT DATAº.
WIRING DIAGRAM
Refer to DTC P1780 on page DI±479.
INSPECTION PROCEDURE
Refer to DTC P1780 (Park/Neutral Position Switch Malfunction) on page DI±479.
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
DI08A±06
Page 2789 of 4770

A07450
Ignition SwitchW±R B±RInstrument Panel J/B
FL
MAINFusible
Link
Block
BatteryJunction
ConnectorECM
B±R
W±R
BR
BR
W±B
B±Y
B
6
7
2 4
17
2 5
4
1 1B
AA F4 F6 E10E7
2F 2K 2J
2L
2AEFI EFI
RelayEngine Room
J/B+B
E1 17 16
AM2
EB EC
J28
3
1E72
MREL
E78IGSW
J27
1W
1B7
5 IGN
1K3
1K5
B+ B
B±Y
B±W
B±W
J35 J35
C
C
Junction
Connector
B±GJ22
Junction
Connector
± DIAGNOSTICSENGINE (1MZ±FE)
DI±369
604 Author: Date:
ECM Power Source Circuit
CIRCUIT INSPECTION
When the ignition switch is turned on, battery positive voltage is applied to terminal IGSW of the ECM and
the EFI main relay (Marking: EFI) control circuit in the ECM sends a signal to terminal MREL of the ECM
switching on the EFI main relay.
This signal causes current to flow to the coil, closing the contacts of the EFI, main relay and supplying power
to terminals +B of the ECM.
If the ignition switch is turned off, the ECM continues to switch on the EFI main relay for a maximum of 2
seconds for the initial setting of the IAC valve.
WIRING DIAGRAM
DI4DU±01
Page 2790 of 4770
A02382
+B (+)
E1 (±)
A02951
IGSW (+)
DI±370
± DIAGNOSTICSENGINE (1MZ±FE)
605 Author: Date:
INSPECTION PROCEDURE
1 Check voltage between terminals +B and E1 or ECM connectors.
PREPARATION:
(a) Remove the glove compartment (See page SF±73).
(b) Turn the ignition switch ON.
CHECK:
Measure voltage between terminals +B and E1 of the ECM
connectors.
OK:
Voltage: 9 ~ 14 V
OK Proceed to next circuit inspection shown on
problem symptoms table (See page DI±221).
NG
2 Check for open in harness and connector between terminals E1 of ECM and
body ground (See page IN±31).
NG Repair or replace harness or connector.
OK
3 Check voltage between terminal IGSW of ECM and body ground.
PREPARATION:
Turn the ignition switch ON.
CHECK:
Measure voltage between terminal IGSW of ECM connectors
and body ground.
OK:
Voltage: 9 ~ 14 V
OK Go to step 6.
NG
Page 2791 of 4770
S04164
IGN Fuse
Instrument Panel J/B
± DIAGNOSTICSENGINE (1MZ±FE)
DI±371
606 Author: Date:
4 Check EFI fuse.
PREPARATION:
Remove IGN fuse from instrument panel J/B.
CHECK:
Check continuity of IGN fuse.
OK:
Continuity
NG Check for short in all the harness and compo-
nents connected to IGN fuse
(See attached wiring diagram).
OK
5 Check ignition switch (See page BE±13).
NG Replace ignition switch.
OK
Check and repair harness and connector be-
tween battery and ignition switch, and igni-
tion switch and ECM.
Page 2792 of 4770
A02952
MREL (+)
DI±372
± DIAGNOSTICSENGINE (1MZ±FE)
607 Author: Date:
6 Check voltage between terminal MREL of ECM and body ground.
PREPARATION:
Turn the ignition switch ON.
CHECK:
Measure voltage between terminal MREL of the ECM
connectors and body ground.
OK:
Voltage: 9 ~ 14 V
NG Check and replace ECM (See page DI±197).
OK
7 Check EFI No.1 fuse of engine room J/B.
NG Check for short in all the harness and compo-
nents connected to EFI No.1 fuse
(See attached wiring diagram).
OK
8 Check EFI main relay (Marking: EFI) (See page SF±53).
NG Replace EFI main relay (Marking: EFI).
OK