1999 TOYOTA CAMRY relay

A07149
ON
TPC
OFFON
VSV is ON
VSV is OFF
Air
E
FG Air
G E
F
± DIAGNOSTICSENGINE (1MZ±FE)
DI±329
564 Author: Date:
8 Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and VSV for EVAP and ECM (See page IN±31).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±31).
9 Check VSV for vapor pressure sensor.
PREPARATION:
(a) Remove the glove compartment (See page SF±73).
(b) Turn the ignition switch ON.
CHECK:
Check VSV function.
(1) Connect between terminal TPC of the ECM connec-
tor and body ground (ON).
(2) Disconnect between terminal TPC of the ECM
connector and body ground (OFF).
OK:
(1) VSV is ON:
Air from pipe E is flowing out through pipe F.
(2) VSV is OFF:
Air from pipe E flows out through pipe G.
OK Check and replace charcoal canister
(See page EC±6).
NG

DI±330
± DIAGNOSTICSENGINE (1MZ±FE)
565 Author: Date:
10 Check operation of VSV for vapor pressure sensor (See page SF±62).
OK Go to step 11.
NG
Replace VSV and clean the vacuum hoses between charcoal canister and VSV for vapor pressure
sensor, and VSV for vapor pressure sensor and vapor pressure sensor, and then check the char-
coal canister.
11 Check for open and short in harness and connector between EFI main relay
(Marking: EFI) and VSV for vapor pressure sensor, and VSV for vapor pressure
sensor and ECM (See page IN±31).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±31).
12 Check the fuel tank over fill check valve (See page EC±6).
NG Replace fuel tank over fill check valve or fuel
tank.
OK
Check and replace charcoal canister
(See page EC±6).

P01559
Throttle Valve
From
Air
Cleaner
Signal
ECM
ValveIAC Valve
To Cylinders Intake Air Chamber
A07448
From
BatteryFL
MAIN
EC
F4 F611Fusible
Link
Block
B1
7 2
5EFI Engine Room J/B
EFI Relay1
23
5 2A
2K 2J
2C W±BIAC Valve
J27J28
B±Y
9II3
21
3E1116
15ECM
RSO
E01
RSC
E01 AA
B±W
MREL
B+ E11
E78
B±G
BB±YB±Y
J36
J35 AC J16
Junction
Connector
B±YR±W
Y±B
B±W
Junction
ConnectorB
Junction
Connector B DI±336
± DIAGNOSTICSENGINE (1MZ±FE)
571 Author: Date:
DTC P0505 Idle Control System Malfunction
CIRCUIT DESCRIPTION
The rotary solenoid type IAC valve is located in front of the in-
take air chamber and intake air bypassing the throttle valve is
directed to the IAC valve through a passage.
In this way the intake air volume bypassing the throttle valve is
regulated, controlling the engine speed.
The ECM operates only the IAC valve to perform idle±up and
provide feedback for the target idling speed.
DTC No.DTC Detecting ConditionTrouble Area
P0505Idle speed continues to vary greatly from target speed
(2 trip detection logic)

IAC valve is stuck or closed

Open or short in IAC valve circuit

Open or short in A/C signal circuit

Air intake (hose loose)

ECM
WIRING DIAGRAM
DI083±06

DI±350
± DIAGNOSTICSENGINE (1MZ±FE)
585 Author: Date:
2 Check resistance of A/F sensor heaters (bank 1, 2 sensor 1) (See page SF±68).
NG Replace A/F sensors (bank 1, 2 sensor 1).
OK
Check and repair harness or connector between EFI main relay (Marking: EFI) and A/F sensors
(bank 1, 2 sensor 1), and A/F sensors (bank 1, 2 sensor 1) and ECM (See page IN±31).

DI±356
± DIAGNOSTICSENGINE (1MZ±FE)
591 Author: Date:
10 Check EFI main relay (Marking: EFI) (See page SF±53).
NG Replace EFI main relay (Marking: EFI).
OK
Replace igniter.

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 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
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

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

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