TOYOTA CAMRY 1999 Service Repair Manual

A09401
Engine Room J/B No.2
EFI11
B
Battery B±G11
2A E4ECM
F9BATT
2JB±Y
F118
FL Block
MAIN FL DI±110
± DIAGNOSTICSENGINE
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 circuit
Open 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 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 was warmed up or not, the air±fuel ratio was lean
or rich, etc. at the time of the malfunction.
DI01I±12

A09286AB0117
A09271
LOCK
BATT
(±) (+)
A00356
Engine Room J/B No.2
EFI Fuse
± DIAGNOSTICSENGINE
DI±111
1 Check voltage between terminal BATT of ECM connector and body ground.
PREPARATION:
Remove the glove compartment (See Pub. No. RM654U, page
SF±64).
CHECK:
Measure the voltage between terminal BATT of the ECM con-
nector and body ground.
OK:
Voltage 9 ± 14 V
OK Check and replace ECM (See page IN±29).
NG
2 Check EFI fuse.
PREPARATION:
Remove the EFI fuse from the engine room J/B No.2.
CHECK:
Check the continuity of the 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±29).

DI±112
± DIAGNOSTICSENGINE
DTC P1780 Park/Neutral Position Switch Malfunction
CIRCUIT DESCRIPTION
The park/neutral position switch goes 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 positive 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 P, R, N, D, 2
and L positions (2 trip detection logic)
P1780
When driving under conditions (a) and (b) for 30 sec. or more
park/neutral position switch is ON (N position):
(2 trip detection logic)
(a) Vehicle speed: 80 km/h (50 mph) or more
(b) Engine speed: 2,000 ± 5,000 rpm
Short 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 the
CURRENT DATA.
WIRING DIAGRAM
Refer to DTC P1780 on page DI±165.
INSPECTION PROCEDURE
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 was warmed up or not, the air±fuel ratio was lean
or rich, etc. at the time of the malfunction.
Refer to DTC P1780 on page DI±165.
DI01J±07

DI±112
± DIAGNOSTICSENGINE
DTC P1780 Park/Neutral Position Switch Malfunction
CIRCUIT DESCRIPTION
The park/neutral position switch goes 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 positive 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 P, R, N, D, 2
and L positions (2 trip detection logic)
P1780
When driving under conditions (a) and (b) for 30 sec. or more
park/neutral position switch is ON (N position):
(2 trip detection logic)
(a) Vehicle speed: 80 km/h (50 mph) or more
(b) Engine speed: 2,000 ± 5,000 rpm
Short 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 the
CURRENT DATA.
WIRING DIAGRAM
Refer to DTC P1780 on page DI±165.
INSPECTION PROCEDURE
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 was warmed up or not, the air±fuel ratio was lean
or rich, etc. at the time of the malfunction.
Refer to DTC P1780 on page DI±165.
DI01J±07

A03606
ECM
STA 11
E1 E4 Instrument
Panel J/BPark/Neutral
Position Switch
B
J6 J7
B CJ/C IG210 11
IG26 5
GR B±W
B±WGR B±W
J/C J29
B B 3
1J 4
1K
5
1B 1K5
STARTER
R
8
7
W±R
IG SwitchW±R
Engine Room
J/B No.2B
B FL
Block
B±G
B±R
BatteryStarter 11
W±B
A
J9
J/C
IF
42L
1
2A
3
2B
AM2
MAINST
Relay11 2 J
92K 52D 1 1
F11 F91 5
2 3
S2B±R MAIN
FL
GR
S1
GR
J6
± DIAGNOSTICSENGINE
DI±113
Starter Signal Circuit
CIRCUIT DESCRIPTION
When the engine is cranked, the intake air flow is slow, so fuel vaporization is poor. A rich mixture is therefore
necessary in order to achieve good startability. While the engine is being cranked, the battery positive volt-
age is applied to terminal STA of the ECM. The starter signal is mainly used to increase the fuel injection
volume for the starting injection control and after±start injection control.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
This diagnostic chart is based on the premise that the engine is cranked normally. If the engine is not
cranked, proceed to the problem symptoms table on page DI±21.
DI01K±12

BE6653A03027A09272
START
STA
(±) (+)
DI±114
± DIAGNOSTICSENGINE
TOYOTA hand±held tester:
1 Connect TOYOTA hand±held tester, and check STA signal.
PREPARATION:
(a) Connect the TOYOTA hand±held tester to the DLC3.
(b) Turn the ignition switch ON and push the TOYOTA hand±held tester main switch ON.
CHECK:
Read the STA signal on the TOYOTA hand±held tester while the starter operates.
OK:
Ignition Switch PositionONSTART
STA signalOFFON
OK Proceed to next circuit inspection shown on
problem symptoms table (See page DI±21).
NG
2 Check for open in harness and connector between ECM and starter relay (Mark-
ing: ST) (See page IN±29).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±29).
OBD II scan tool (excluding TOYOTA hand±held tester):
1 Check voltage between terminal STA of ECM connector and body ground.
PREPARATION:
(a) Remove the glove compartment (See Pub. No. RM654U,
page SF±64).
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal STA of the ECM connec-
tor and body ground, during the engine cranking.
OK:
Voltage: 6 V or more
OK Proceed to next circuit inspection shown on
problem symptoms table (See page DI±3).

± DIAGNOSTICSENGINE
DI±115
NG
2 Check for open in harness and connector between ECM and starter relay (Mark-
ing: ST) (See page IN±29).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±29).

A09403
ECM
+B 12
E4 B±Y J/C
B
J24 J23B
B±Y
Instrument
Panel J/B 22J 2K7
W±R EFI
Relay 1 3
52
2F4
W±B
2A 1
AM2
42L
B
FL
Block
MAIN
FL
B±GEngine
J/B No.2
5
1B
531K71W
IGN
1K
Room
W±R
IG
Switch
7 6
E6
BR
B±R
EC
E1
F11
F9EB
1
1
EFI
J20
J/C A
A
Battery
BR
16 B±R DI±116
± DIAGNOSTICSENGINE
ECM Power Source Circuit
CIRCUIT DESCRIPTION
When the ignition switch is turned ON, battery positive voltage is applied to the coil, closing the contacts of
the EFI main relay (Marking: EFI) and supplying power to terminal +B of the ECM.
WIRING DIAGRAM
DI01L±07

A09291BE6653
A09273
ON
+B
E1
(±) (+)
± DIAGNOSTICSENGINE
DI±117
INSPECTION PROCEDURE
1 Check voltage between terminals +B and E1 of ECM connector.
PREPARATION:
(a) Remove the glove compartment (See Pub. No. RM654U,
page SF±64).
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminals +B and E1 of the ECM
connector.
OK:
Voltage: 9 ± 14 V
OK Proceed to next circuit inspection shown on
Problem symptoms table (See page DI±21).
NG
2 Check for open in harness and connector between terminal E1 of ECM and body
ground (See page IN±29).
NG Repair or replace harness or connector.
OK
3 Check EFI main relay (Marking: EFI) (See Pub. No. RM654U, page SF±40).
NG Replace EFI main relay.
OK
4 Check EFI fuse (See page DI±110, step 2).
NG Check for short in all harness and components
connected to EFI fuse.
OK

A00355
IGN Fuse
Instrument Panel J/B
DI±118
± DIAGNOSTICSENGINE
5 Check for open in harness and connector between EFI main relay (Marking: EFI)
and battery, and EFI main relay and ECM (See page IN±29).
NG Repair or replace harness or connector.
OK
6 Check IGN fuse.
PREPARATION:
Remove the IGN fuse from the instrument panel J/B.
CHECK:
Check the continuity of the IGN fuse.
OK:
Continuity
NG Check for short in all harness and components
connected to IGN fuse.
OK
7 Check ignition switch (See Pub. No. RM654U, page BE±14).
NG Replace ignition switch.
OK
Check for open in harness and connector between ignition switch and EFI main relay, and EFI
main relay and body ground (See page IN±29).