1996 TOYOTA T100 engine

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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).

Downloaded from www.Manualslib.com manuals search engine DI−178
− 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

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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

Downloaded from www.Manualslib.com manuals search engine S00901
Battery W−RW−R
R−L W
AM2
2
2 4
3R/B No.28
IA3
8
7Switch IG
B−R
IE114
B−R
B−RB−R
B−R 2
B−R 2
B−R 2
B−R 2
B−R 2
B−R 2Injector
No.1
No.2
No.3
No.4
No.5
No.61
1
1
1
1
1W−R
W
W−G
Y−R
W−L
Y−B
BR
BRE7 E7
E7 E7
E7 E7
E7 E7
E7 E7
E7 E7
E7 E7
E7 E7
(M/T)(A/T)
EB
12 10
11 9
25 8
10 7
96
85
13 34
26 33#10
#20
#30
#40
#50
#60
E01
E02ECM
FI6588
FI6538
A00064
10 V
/Division10 V
/Division
GND GND
100 msec./Division (Idling)1 msec./Division (Idling)
Injection duration
(Magnification)
DI−184
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
WIRING DIAGRAM
Reference INSPECTION USING OSCILLOSCOPE
INJECTOR SIGNAL WAVEFORM
With the engine idling, measure between terminals #10 − #60 and E01 of ECM.
HINT:
The correct waveform is as shown.