sensor TOYOTA T100 1996 Factory Service Manual

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DI−179
1996 TOYOTA T100 (RM449U)
3 Check output voltage of heated oxygen sensor.
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 the heated oxygen sensor (bank 1 sensor 2) when the engine suddenly raced.
HINT:
Perform quick racing to 4,000 rpm 3 min. using the accelerator pedal.
OK:
Heated oxygen sensor output voltage: Alternates from 0.4 V or less to 0.5 V or more
OK Check that each connector is properly
connected.
NG
Replace heated oxygen sensor.

Downloaded from www.Manualslib.com manuals search engine DI−180
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
DTC P0171 System too Lean (Fuel Trim)
DTC P0172 System too Rich (Fuel Trim)
CIRCUIT DESCRIPTION
Fuel trim refers to the feedback compensation value compared against the basic injection time. Fuel trim
includes short−term fuel trim and long−term fuel trim.
Short−term fuel trim is the short−term fuel compensation used to maintain the air−fuel ratio at its ideal
theoretical value. The signal from the heated oxygen sensor indicates whether the air−fuel ratio is RICH or
LEAN compared to the ideal theoretical value, triggering a reduction in fuel volume if the air−fuel ratio is rich,
and an increase in fuel volume if it is lean.
Long−term fuel trim is overall fuel compensation carried out long−term to compensate for continual deviation
of the short−term fuel trim from the central value due to individual engine differences, wear over time and
changes in the usage environment.
If both the short−term fuel trim and long−term fuel trim are LEAN or RICH beyond a certain value, it is
detected as a malfunction and the MIL lights up.
DTC No.DTC Detecting ConditionTrouble Area
P0171
When air fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on RICH side
(2 trip detection logic)
Air intake (hose loose)
Fuel line pressure
Injector blockage
Heated oxygen sensor (bank 1 sensor 1) malfunction
Mass air flow meter
Engine coolant temp. sensor
P0172
When air fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on LEAN side
(2 trip detection logic)
Fuel line pressure
Injector leak, blockage
Heated oxygen sensor (bank 1 sensor 1) malfunction
Mass air flow meter
Engine coolant temp. sensor
HINT:
When DTC P0171 is recorded, the actual air−fuel ratio is on the LEAN side. When DTC P0172 is re-
corded, the actual air−fuel ratio is on the RICH side.
If the vehicle runs out of fuel, the air−fuel ratio is LEAN and DTC P0171 is recorded. The MIL then
comes on.
If the total of the short−term fuel trim value and long−term fuel trim value is within ± 25 %, the system
is functioning normally.
INSPECTION PROCEDURE
1 Check air induction system (See page SF−5).
NG Repair or replace.
OK
DI0US−01

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DI−181
1996 TOYOTA T100 (RM449U)
2 Check for heated oxygen sensor (bank 1 sensor 1) 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 (bank 1 sensor 1) 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
3 Check for heated oxygen sensor
(bank 1 sensor 1) (See page DI−172).
1, 2
3 Check fuel pressure (See page SF−5).
NG Check and repair fuel pump, pressure
regulator, fuel pipe line and filter
(See page SF−5).
OK
4 Check injector injection (See page SF−21).
NG Replace injector.
OK

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− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
5 Check mass air flow meter and engine coolant temp. sensor
(See page SF−29, SF−52).
NG Repair or replace.
OK
6 Check for spark and ignition (See page IG−1).
NG Repair or replace.
OK
Check and replace ECM (See page IN−26).

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DI−183
1996 TOYOTA T100 (RM449U)
DTC P0300 Random/Multiple Cylinder Misfire Detected
DTC P0301 Cylinder 1 Misfire Detected
DTC P0302 Cylinder 2 Misfire Detected
DTC P0303 Cylinder 3 Misfire Detected
DTC P0304 Cylinder 4 Misfire Detected
DTC P0305 Cylinder 5 Misfire Detected
DTC P0306 Cylinder 6 Misfire Detected
CIRCUIT DESCRIPTION
Misfire: The ECM uses the crankshaft position sensor and camshaft position sensor to monitor changes in
the crankshaft rotation for each cylinder.
The ECM counts the number of times the engine speed change rate indicates that misfire has occur-
red.When the misfire rate equals or exceeds the count indicating that the engine condition has deteriorated,
the MIL lights up.
If the misfire rate is high enough and the driving conditions will cause catalyst overheating, the MIL blinks
when misfiring occurs.
DTC No.DTC Detecting ConditionTrouble Area
P0300Misfiring of random cylinders is detected during any
particular 200 or 1,000 revolutionsIgnition system
Injector
Fuel line pressure
EGR*
Compression pressure
Valve clearance not to specification
Valve timing
Mass air flow meter
Engine coolant temp. sensor
P0301
P0302
P0303
P0304
P0305
P0306For any particular 200 revolutions for engine, misfiring is
detected which can cause catalyst overheating
(This causes MIL to blink)
For any particular 1,000 revolutions of engine, misfiring is de-
tected which causes a deterioration in emission
(2 trip detection logic)
*: Only for 2WD models with a load capacity of 0.5 ton and regular cab.
HINT:
When the 2 or more codes for a misfiring cylinder are recorded repeatedly but no Random Misfire
code is
recorded, it indicates that the misfires were detected and recorded at different times.
DI0UT−01

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DI−187
1996 TOYOTA T100 (RM449U)
5 Check injector injection (See page SF−21).
NG Replace injector.
OK
6 Check EGR system (See page EC−9).*
NG Repair EGR system.*
OK
*: Only for 2WD models with a load capacity of 0.5 ton and regular cab.
7 Check mass air flow meter and engine coolant temp. sensor (See page SF−29
and SF−52).
NG Repair or replace.
OK
Check the compression pressure (See page EM−2), valve clearance (See page EM−4) and valve
timing (See page EM−17).

Downloaded from www.Manualslib.com manuals search engine P19919
ECM
KNK1
KNK2E1
E1 617
316 E6
E6E6
E6
(M/T)(A/T) BB
GRGR EC1
EC11
2 1
1 Knock Sensor 1
(On right bank)
Knock Sensor 2
(On left bank) DI−188
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
DTC P0325 Knock Sensor 1 Circuit Malfunction
DTC P0330 Knock Sensor 2 Circuit Malfunction
CIRCUIT DESCRIPTION
Knock sensors are fitted one to the right bank and left bank of the cylinder block to detect engine knocking.
This sensor contains a piezoelectric element which generates a voltage when it becomes deformed, which
occurs when the cylinder block vibrates due to knocking. If engine knocking occurs, ignition timing is retarded
to suppress it.
DTC No.DTC Detecting ConditionTrouble Area
P0325No knock sensor 1 signal to ECM with engine speed between
1,760 rpm and 5,600 rpmOpen or short in knock sensor 1 circuit
Knock sensor 1 (looseness)
ECM
P0330No knock sensor 2 signal to ECM with engine speed between
1,760 rpm and 5,600 rpmOpen or short in knock sensor 2 circuit
Knock sensor 2 (looseness)
ECM
If the ECM detects the above diagnosis conditions, it operates the fail safe function in which the corrective
retard angle value is set to the maximum value.
WIRING DIAGRAM
DI0UU−01

Downloaded from www.Manualslib.com manuals search engine A00053
A00054 P20457
A00112
ECM
Knock Sensor
Female
ConnectorMale
Connector 11
2
2
E6 E6
E6
E6KNK1
KNK2 17 6
3161
1
(M/T)(A/T)
EC1
EC1
− DIAGNOSTICSENGINE (5VZ−FE)
DI−189
1996 TOYOTA T100 (RM449U)
INSPECTION PROCEDURE
HINT:
DTC P0325 is for the right bank knock sensor circuit. DTC P0330 is for the left bank knock sensor circuit.
1 Connect OBD II scan tool or TOYOTA hand−held tester and check knock sensor
circuit.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand−held tes-
ter to the DLC3.
(b) Disconnect the wire to wire connector EC1.
(c) Connect the terminals of the disconnected EC1 male con-
nector and EC1 female as follows.
Male connector ↔Female connector
Terminal 1 ↔ Terminal 2
Terminal 2 ↔ Terminal 1
(d) Turn the ignition switch ON and push the OBDII scan tool
or TOYOTA hand−held tester main switch ON.
(e) After the engine is warmed up, perform quick racing to
4,000 rpm 3 times.
CHECK:
Check the DTC.
RESULT:
Type IDTC same as when vehicle brought in
P0325 → P0325 or P0330 → P0330
Type IIDTC different to when vehicle brought in
P0325 → P0330 or P0330 → P0325
Type II Go to step 3.
Type I
2 Check for open and short in harness and connector between EC1 connector and
ECM (See page IN−26).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page
IN−26).

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KNK signal waveform
0.5 V
/Division
5 msec./Division
100 μsec./Division 0V
200 mV
/Division
0V DI−190
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
3 Check for open and short in harness and connector between EC1 connector and
knock sensor (See page IN−26).
HINT:
If DTC P0325 has changed to P0330, check the knock sensor circuit on the right bank side.
If DTC P0330 has changed to P0325, check the knock sensor circuit on the left bank side.
NG Repair or replace harness or connector.
OK
Replace knock sensor.
Reference INSPECTION USING OSCILLOSCOPE
With the engine racing (4,000 rpm), measure between
terminal KNK1, KNK2 of ECM and body ground.
HINT:
The correct waveform is as shown.
Spread the time on the horizontal axis, and confirm that
period of the wave is 141 μsec (Normal mode vibration
frequency of knock sensor: 7.1 kHz).
HINT:
If normal mode vibration frequency is not 7.1 kHz, the sensor
is malfunctioning.

Downloaded from www.Manualslib.com manuals search engine P25501
ECM
G
G−
NE
NE− B
W
G
L 1
2
1
2 Camshaft Position Sensor
Crankshaft Position Sensor11 1 0
511
12 5
66 E5 E5
E5
E5E6
E6
E6
E6
E1
(M/T) (A/T)
− DIAGNOSTICSENGINE (5VZ−FE)
DI−191
1996 TOYOTA T100 (RM449U)
DTC P0335 Crankshaft Position Sensor ”A” Circuit
Malfunction
CIRCUIT DESCRIPTION
The crankshaft position sensor, which detects the engine speed and crankshaft angle signal (NE signal),
has been installed on the oil pump body.
The NE signal plate has 34 teeth. The NE signal sensor generates 34 signals of every engine revolution.
The ECM detects the standard crankshaft angle based on the G signals, and the actual crankshaft angle
and the engine speed by the NE signals.
DTC No.DTC Detecting ConditionTrouble Area
P0335
No crankshaft position sensor signal to ECM during cranking
(2 trip detection logic)Open or short in crankshaft position sensor circuit
Crankshaft position sensor
Starter
ECM
No crankshaft position sensor signal to ECM with engine
speed 600 rpm or more (2 trip detection logic)
WIRING DIAGRAM
DI0UV−01