TOYOTA CAMRY 1999 Service Repair Manual

A00477
CoverAtmosphere
Platinum
Electrode
Solid Electrolyte
(Zirconia Element)
Platinum
Electrode
Heater
Coating (Ceramic)
Exhaust Gas
(V)
4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.6
17
Air±Fuel Ratio
2.4
16 15 12 1413 1918ECM Monitored
A/F Sensor Voltage
± DIAGNOSTICSENGINE (1MZ±FE)
DI±249
484 Author: Date:
DTC P0125 Insufficient Coolant Temp. for Closed Loop
Fuel Control (Only for California Spec.)
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three±way
catalytic converter is used, but for the most efficient use of the three±way catalytic converter, the air±fuel
ratio must be precisely controlled so that it is always close to the stoichiometric air±fuel ratio.
The A/F sensor has the characteristic that provides output voltage
* approximately proportional to the existing
air±fuel ratio. The A/F sensor output voltage
* is used to provide feedback for the ECM to control the air±fuel
ratio.
By the A/F sensor output, the ECM can determine the deviation amount from the stoichiometric air±fuel ratio
and control the proper injection time immediately. If the A/F sensor is malfunctioning, ECM is unable to per-
form accurate air±fuel ratio control.
The A/F sensor is equipped with a heater which heats the zirconia element. The heater is controlled by the
ECM. When the intake air volume is low (the temp. of the exhaust gas is low), current flows to the heater
to heat the sensor for accurate oxygen concentration detection.
*: The voltage value changes at the inside of the ECM only.
DTC No.DTC Detecting ConditionTrouble Area
P0125
After engine is warmed up, A/F sensor output* does not
change when conditions (a), (b) and (c) continue for at least
1.5 min.
*: Output value changes at inside of ECM only.
(a) Engine speed: 1,500 rpm or more
(b) Vehicle speed: 40 ~ 100 km/h (25 ~ 62 mph)
(c) Throttle valve does not fully closed
(d) After starting engine
140 sec
Fuel system

Injector

Ignition system

Gas leakage on exhaust system

Open or short in A/F sensor circuit (bank 1, 2 sensor 1)

A/F sensors (bank 1, 2 sensor 1)

ECM
DI07M±09

A07445
B
BB B
2 142
31 23
4
BR
23
1
B±W P±BB B±WB±R
*
1L
E8 E8 E10 E10
E78 9 84 213 122011
AFR+
AFR±
AFL+
AFL± HAFR
OXS
HTS
MREL HAFLECM
3.3 V
3.3 V 3.0 V
3.0 V
E1
B+ E10 E10E10E10 1
J27
Engine Room J/B
F6
F4 2J
2A
2C2K
2
7
5 1
EFI Relay
1
1B
B±W
B±W
B EFI
1 2
2
52
22 3
L W±B1
1 2
A/F HTR
1
W
FL
MAIN FLEngine RoomBattery*
1B±W B
B
B±G
1
2 3
5
E04
E05
E03
*1B±R *1BR *G
*G
*B±W*L
ES1
J27 B
E
Junction
connector
A/F Sensor
(Bank 2, Sensor 1)
B±Y
A/F Sensor
(Bank 1, Sensor 2)
BRII1A
ABR
J22
Junction
Connector J24
Junction
Connector
B±Y
W±B
B±W
J35
J35J36A C
C
EB EC
A/F Sensor
(Bank 1, Sensor 1)
Engine Room
A/F HTR Relay
*: TMC Made
*: TMMK Made
Junction
Connector
4
to Analog±Digital
Converter
to Analog±Digital
Converter
DI±250
± DIAGNOSTICSENGINE (1MZ±FE)
485 Author: Date:
HINT:

After confirming DTC P0125, use the OBD II scan tool or TOYOTA hand-held tester to confirm voltage
output of heated oxygen sensors (bank 1, 2 sensor 1) from CURRENT DATA.

The ECM controls the voltage of AFR, AFL, AFR and AFL terminals of ECM to the fixed volt-
age. Therefore, it is impossible to confirm the A/F sensor output voltage without OBD II scan tool or
TOYOTA hand±held tester.

OBD II scan tool (excluding TOYOTA hand±held tester) displays the one fifth of the A/F sensor output
voltage which is displayed on the TOYOTA hand±held tester.
WIRING DIAGRAM

± DIAGNOSTICSENGINE (1MZ±FE)
DI±251
486 Author: Date:
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 warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
1 Are there any other codes (besides DTC P0125) being output ?
YES Go to relevant DTC chart.
NO

DI±252
± DIAGNOSTICSENGINE (1MZ±FE)
487 Author: Date:
2 Connect the OBD II scan tool or TOYOTA hand±held tester, and read value for
voltage output of A/F sensors (bank 1, 2 sensor 1).
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(b) Warm up the A/F sensors (bank 1, 2 sensor 1) with the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Read voltage value of A/F sensors (bank 1, 2 sensor 1) on the screen of OBD II scan tool or TOYOTA hand±
held tester, when you perform all the following conditions.
HINT:
The voltage of AFR,AFL terminal of ECM is 3.3 fixed and the AFR,AFL terminal is 3.0 V fixed.
Therefore, it is impossible to check the A/F sensor output voltage at the terminals (AFR,AFL/
AFR,AFL) of ECM.
OK:
ConditionA/F Sensor Voltage value
Engine idlingN t i t 3 3 V (*0 660 V)E i idli
Not remains at 3.3. V (*0.660 V)Engine idlingNot remains at 3.3. V ( 0.660 V)

Not remains at38V(
*0 76 V) or more
Driving at engine speed 1,500 rpm or more and vehicle
speed 40 km/h (25 mph) or move, and operate throttle valve
open and close

Not remains at 3.8 V (*0.76 V) or more

Not remains at 2.8 V (*0.56 V) or less
*: When you use the OBD II scan tool (excluding TOYOTA hand±held tester)
HINT:

During fuel enrichment, there is a case that the output voltage of A/F sensors (bank 1, 2 sensor 1) is
below 2.8 V (
* 0.56 V), it is normal.

During fuel cut, there is a case that the output voltage of A/F sensors (bank 1, 2 sensor 1) is above
3.8 V (
* 0.76 V), it is normal.


If output voltage of A/F sensors (bank 1, 2 sensor 1) remains at 3.30 V (* 0.660 V) even after performing
all the above conditions, A/F sensors (bank 1, 2 sensor 1) circuit may be open.

If output voltage of A/F sensor remains at 3.8 V (* 0.76 V) or more, or 2.8 V (* 0.56 V) or less even after
performing all the above conditions, A/F sensors (bank 1, 2 sensor 1) circuit may be short.
*: When you use the OBD II scan tool (excluding TOYOTA hand±held tester).
OK Go to step 10.
NG
3 Check for open and short in harness and connector between ECM and A/F
sensors (bank1, 2 sensor1) (See page IN±31).
NG Repair or replace harness or connector.
OK

± DIAGNOSTICSENGINE (1MZ±FE)
DI±253
488 Author: Date:
4 Check resistance of A/F sensor heaters (bank1, 2 sensor1) (See page SF±68).
NG Replace A/F sensor.
OK
5 Check air induction system (See page SF±1).
NG Repair or replace.
OK
6 Check EGR system (See page EC±11).
NG Replace EGR system.
OK
7 Check fuel pressure (See page SF±21).
NG Check and repair fuel pump, fuel pipe line and
filter (See page SF±1).
OK
8 Check injector injection (See page SF±25).
NG Replace injector.
OK

DI±254
± DIAGNOSTICSENGINE (1MZ±FE)
489 Author: Date:
9 Check gas leakage on exhaust system.
NG Repair or replace
OK
Replace A/F sensors (bank1, 2 sensor1).
10 Perform confirmation driving pattern (See page DI±340).
Go
11 Is there DTC P0125 being output again ?
YES Check and replace ECM
(See page IN±31).
NO
12 Did vehicle runs out of fuel in the past ?
NO Check for intermittent problems
(See page DI±197).
YES
DTC P0125 is caused by running out of fuel.

A01666
Vehicle speed
50 ~ 65 km/h
(31 ~ 40 mph)
(5)Idling
IG SW OFF
1 ~ 3 min. 1 min.Time
(2)
(1)(3)(4)
± DIAGNOSTICSENGINE (1MZ±FE)
DI±255
490 Author: Date:
DTC P0130 Heated Oxygen Sensor Circuit Malfunction
(Bank 1 Sensor 1) (Except California Spec.)
DTC P0150 Heated Oxygen Sensor Circuit Malfunction
(Bank 2 Sensor 1) (Except California Spec.)
CIRCUIT DESCRIPTION
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control) on page DI±244.
DTC No.DTC Detecting ConditionTrouble Area
P0130
P0150Voltage output of heated oxygen sensor remains at 0.4 V or
more, or 0.55 V or less, during idling after engine is warmed up
(2 trip detection logic)
Heated oxygen sensor

Fuel trim malfunction
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 closer to the engine body.
The heated oxygen sensor's output voltage and the short-term fuel trim value can be read using the
OBD II scan tool or TOYOTA hand-held tester.
WIRING DIAGRAM
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control) on page DI±244.
CONFIRMATION DRIVING PATTERN
(1) Connect the TOYOTA hand±held tester to the DLC3.
(2) Switch the TOYOTA hand±held tester from normal mode to check mode (See page DI±197).
(3) Start the engine and warm it up with all accessory switches OFF.
(4) Drive the vehicle at 50 ~ 65 km/h (31 ~ 40 mph) for 1 ~ 3 min. to warm up the heated oxygen sensor.
(5) Let the engine idle for 1 min.
(6) Perform steps (3) to (5) three times.
DI07N±07

P18349
DI±256
± DIAGNOSTICSENGINE (1MZ±FE)
491 Author: Date:
HINT:
If a malfunction exists, the MIL will light up during step (6).
NOTICE:
If the conditions in this test are not strictly followed, detection of the malfunction will not be possible.
If you do not have a TOYOTA hand±held tester, turn the ignition switch OFF after performing steps
(3) to (6), then perform steps (3) to (6) again.
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 warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
1 Are there any other codes (besides DTC P0130, P0150) being output ?
YES Go to relevant DTC chart.
NO
2 Check the output voltage of heated oxygen sensors (bank1, 2 sensor1)
during idling.
PREPARATION:
Warm up the heated oxygen sensors (bank1, 2 sensor1) with the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Use the OBD II scan tool or TOYOTA hand±held tester to read the output voltage of the heated oxygen sen-
sors (bank1, 2 sensor1) during idling.
OK:
Heated oxygen sensors (bank1, 2 sensor1) output voltage:
Alternates repeatedly between less than 0.4 V and more than 0.55 V (See the following table).
OK Go to step 8.
NG

± DIAGNOSTICSENGINE (1MZ±FE)
DI±257
492 Author: Date:
3 Check for open and short in harness and connector between ECM and heated
oxygen sensors (bank1, 2 sensor1) (See page IN±31).
NG Repair or replace harness or connector.
OK
4 Check air induction system (See page SF±1).
NG Repair or replace.
OK
5 Check EGR system (See page EC±11).
NG Replace EGR system.
OK
6 Check fuel pressure (See page SF±6).
NG Check and repair fuel pump, fuel pipe line and
filter (See page SF±1).
OK

DI±258
± DIAGNOSTICSENGINE (1MZ±FE)
493 Author: Date:
7 Check injector injection (See page SF±25).
NG Replace injector.
OK
Replace heated oxygen sensors
(bank1, 2 sensor1).
8 Perform confirmation driving pattern.
Go
9 Are there DTC P0130 and/or P0150 being output again ?
NO Check for intermittent problems
(see page DI±197).
YES
Check and replace ECM
(See page IN±31).