sensor TOYOTA T100 1996 Factory Service Manual

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A00027
Atomosphere
CoverIdeal Air−Fuel Mixture
Exhaust GasFlange
Platinum Electrode
Solid Electrolyte
(Zirconia Element)
Platinum Electrode
Heater
Coating(Ceramic)
Output Voltage
Richer  Air−fuel Ratio  Leaner
− DIAGNOSTICSENGINE (5VZ−FE)
DI−169
1996 TOYOTA T100 (RM449U)
DTC P0125 Insufficient Coolant Temp. for Closed Loop
Fuel Control
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 oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity of the
stoichiometric air−fuel ratio. This characteristic is used to detect the oxygen concentration in the exhaust
gas and provide feedback to the computer for control of the air−fuel ratio.
When the air−fuel ratio becomes LEAN, the oxygen concentration in the exhaust increases and the oxygen
sensor informs the ECM of the LEAN condition (small electromotive force: 0 V).
When the air−fuel ratio is RICHER than the stoichiometric air−fuel ratio the oxygen concentration in the ex-
haust gas is reduced and the oxygen sensor informs the ECM of the RICH condition (large electromotive
force: 1 V). The ECM judges by the electromotive force from the oxygen sensor whether the air−fuel ratio
is RICH or LEAN and controls the injection time accordingly. However, if malfunction of the oxygen sensor
causes output of abnormal electromotive force, the ECM is unable to perform accurate air−fuel ratio control.
The heated oxygen sensors include 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.
DTC No.DTC Detecting ConditionTrouble Area
P0125
After engine is warmed up, heated oxygen sensor output
does not indicate RICH even once when conditions (a), (b),
(c) and (d) continue for at least 1.5 min.:
(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) 140 sec. or more after starting engine
Open or short in heated oxygen sensor
(bank1 sensor 1) circuit
Heated oxygen sensor (bank 1 sensor 1)
DI0UN−01

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R/B No.2
B−W
22E6 E6
E6 E6
BRE1 E1
EB
2
2
22
From Battery
To Body GroundFrom
IG Switch
EFI RelayW−R
EFI
2
2
15 13EA1IE1 W−RW−RW−R 99
W−R
Heated
Oxygen
Sensor
(Bank 1
Sensor 2)2
13
423
14Heated
Oxygen
Sensor
(Bank 1
Sensor 1)
P−G
E5 E7
E7
E5
E5 E7 R−G RECM
OX1
HT1
OX2
E1
HT2E03
E03 (M/T)(A/T)5
3
13
24
913
16
19
16
15 W
BR BR
BR
DI−170
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
HINT:
After confirming DTC P0125 use the OBD II scan tool or TOYOTA hand−held tester to confirm voltage output
of heated oxygen sensor from "CURRENT DATA".
If voltage output of heated oxygen sensor is 0 V, heated oxygen sensor circuit may be open or short.
WIRING DIAGRAM
INSPECTION PROCEDURE
1 Connect OBD II scan tool or TOYOTA hand−held tester and read value for
voltage output of heated oxygen sensor (bank 1 sensor 1).
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand−held tester to the DLC3.
(b) Warm up the engine to normal operating temp.
CHECK:
Read voltage output of heated oxygen sensor (bank 1 sensor 1) when engine is suddenly raced.
HINT:
Perform quick racing to 4,000 rpm 3 times using the accelerator pedal.
OK:
Heated oxygen sensor (bank 1 sensor 1) output a RICH signal (0.45 V or more) at least once
OK Check and replace ECM (See page IN−26).
NG

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DI−171
1996 TOYOTA T100 (RM449U)
2 Check for open and short in harness and connector between ECM and heated
oxygen sensor (bank 1 sensor 1) (See page IN−26).
NG Repair or replace harness or connector.
OK
Replace heated oxygen sensor
(bank 1 sensor 1).

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Vehicle speed
50 ∼ 65 km/h
(31 ∼ 40 mph)
Idling
IG SW OFF
1 ∼ 3 min. 1 min. Time
(1)(2)(3)(4)
(5)
DI−172
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
DTC P0130 Heated Oxygen Sensor Circuit Malfunction
(Bank 1 Sensor 1)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI−169.
DTC No.DTC Detecting ConditionTrouble Area
P0130
Voltage output of heated oxygen sensor remains at 0.35 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:
Sensor 1 refers to the sensor closer to the engine body.
The heated oxygen sensor’s output voltage and the shortterm fuel trim value can be read using the
OBD II scan tool or TOYOTA handheld tester.
WIRING DIAGRAM
Refer to DTC P0125 on page DI−169.
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−129).
(3) Start the engine and warm it up with all the 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.
HINT:
If a malfunction exists, the MIL will light up during step (5).
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 (5), then perform steps (3) to (5) again.
DI0UO−01

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DI−173
1996 TOYOTA T100 (RM449U)
INSPECTION PROCEDURE
1 Check for open and short in harness and connector between ECM and heated
oxygen sensor (See page IN−26).
NG Repair or replace harness or connector.
OK
2 Check for heated oxygen sensor data.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand−held tester to the DLC3.
(b) Warm up the engine to normal operating temp.
CHECK:
Read heated oxygen sensor output voltage and short−term fuel trim.
RESULT:
PatternHeated oxygen sensor output voltageShort−term fuel trim
1Lean condition (Changes at 0.55 V or less)Changes at about + 20 %
2Rich condition (Changes at 0.35 V or more)Changes at about − 20 %
3Except 1 and 2Except 1 and 2
1, 2 Check fuel trim system (See page DI−183).
3

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1 V
0.55 V
0.35 V
0 VNG NG NG OK
DI−174
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
3 Check output voltage of heated oxygen sensor during idling.
PREPARATION:
Warm up the heated oxygen sensor with the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Use the OBD II scan tool or TOYOTA hand−held tester read the output voltage of the heated oxygen sensor
during idling.
OK:
Heated oxygen sensor output voltage:
Alternates repeatedly between less than 0.35 V and more than 0.55 V (See the following table)
OK Perform confirmation driving pattern.
NG
Replace heated oxygen sensor.

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DI−175
1996 TOYOTA T100 (RM449U)
DTC P0133 Heated Oxygen Sensor Circuit Slow
Response (Bank 1 Sensor 1)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI−169.
DTC No.DTC Detecting ConditionTrouble Area
P0133
Response time for heated oxygen sensor’s voltage output to
change from rich to lean, or from lean to rich, is 1 sec. or
more during idling after engine is warmed up
(2 trip detection logic)
Heated oxygen sensor
HINT:
Sensor 1 refers to the sensor closer to the engine body.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0133) being output?
YES Go to relevant DTC chart.
NO
Replace heated oxygen sensor.
DI0UP−01

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P24318
P24317A00109
ON
HT1 (+) HT2 (+)
HT1 (+)HT2 (+) For M/T
For A/T
DI−176
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
DTC P0135 Heated Oxygen Sensor Heater Circuit
Malfunction (Bank 1 Sensor 1)
DTC P0141 Heated Oxygen Sensor Heater Circuit
Malfunction (Bank 1 Sensor 2)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI−169.
DTC No.DTC Detecting ConditionTrouble Area
P0135
P0141
When heater operates, heater current exceeds 2.35 A
(2 trip detection logic)Open or short in heater circuit of heated oxygen sensor
Heated oxygen sensor heater
ECM
Heater current of 0.2 A or less when heater operates
(2 trip detection logic)
HINT:
Sensor 1 refers to the sensor closer to the engine body.
Sensor 2 refers to the sensor farther away from the engine body.
WIRING DIAGRAM
Refer to DTC P0125 on page DI−169.
INSPECTION PROCEDURE
1 Check voltage between terminals HT1, HT2 of ECM connector and body ground.
PREPARATION:
(a) Remove the right cowl side trim (See page SF−61).
(b) Turn the ignition switch ON.
CHECK:
Measure voltage between terminals HT1, HT2 of ECM connec-
tor and body ground.
HINT:
Connect terminal HT1 to bank 1 sensor 1.
Connect terminal HT2 to bank 1 sensor 2.
OK:
Voltage: 9 − 14 V
OK Check and replace ECM (See page IN−26).
NG
DI0UQ−01

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DI−177
1996 TOYOTA T100 (RM449U)
2 Check resistance of heated oxygen sensor heater (See page SF−60).
NG Replace heated oxygen sensor.
OK
Check and repair harness or connector
between EFI main relay, heated oxygen
sensor and ECM (See page IN−26).

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− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
DTC P0136 Heated Oxygen Sensor Circuit Malfunction
(Bank 1 Sensor 2)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI−169.
DTC No.DTC Detecting ConditionTrouble Area
P0136
Voltage output of heated oxygen sensor (bank 1 sensor 2)
remains at 0.4 V or more or 0.5 V or less when vehicle is
driven at 50 km/h (31 mph) or more after the engine is
warmed up.
(2 trip detection logic).
Heated oxygen sensor
HINT:
Sensor 2 refers to the sensor farther away from the engine body.
WIRING DIAGRAM
Refer to DTC P0125 on page DI−169.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0136) being output?
YES Go to relevant DTC chart.
NO
2 Check for open and short in harness and connector between ECM and heated
oxygen sensor (See page IN−26).
NG Repair or replace harness or connector.
OK
DI0UR−01