1996 TOYOTA T100 check engine

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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).

Downloaded from www.Manualslib.com manuals search engine P25779
P21163A00110
− DIAGNOSTICSENGINE (5VZ−FE)
DI−185
1996 TOYOTA T100 (RM449U)
INSPECTION PROCEDURE
1 Check spark plug and spark of misfiring cylinder.
PREPARATION:
(a) Remove the ignition coil and high−tension cord.
(b) Remove the spark plug.
CHECK:
(a) Check the spark plug type.
(b) Check for carbon deposits on electrode.
(c) Check the electrode gap.
OK:
(1) Twin ground electrodes type.
Recommended spark plug:
ND K16TR11
NGK BKR5EKB−11
(2) No large carbon deposit present. Not wet with
gosoline or oil.
(3) Electrode gap: 1.0 − 1.1 mm (0.039 − 0.043 in.)
PREPARATION:
(a) Install the spark plug to the ignition coil or high−tension
cord.
(b) Disconnect the injector connector.
(c) Ground the spark plug.
CHECK:
Check if the spark occurs while the engine is being cranked.
NOTICE:
To prevent excess fuel being injected from the injectors
during this test, don’t crank the engine for more than 5 − 10
sec. at a time.
OK:
Spark jumps across electrode gap.
NG Replace or check ignition system (See page
IG−1).
OK

Downloaded from www.Manualslib.com manuals search engine BE6653
P24320
P24319A00111
ON
#10 #20
#30#40 #50 #60 (+) (+) (+) (+) (+)
(+)
#10 #20 #40 #50 #60#30(+) (+) (+) (+) (+) (+)
For M/T
For A/T
DI−186
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
2 Check voltage of ECM terminal for injector of failed cylinder.
PREPARATION:
(a) Remove the right cowl side trim (See page SF−61).
(b) Turn the ignition switch ON.
CHECK:
Measure voltage between applicable terminal of ECM connec-
tor and body ground.
OK:
Voltage: 9 − 14 V
OK Go to step 4.
NG
3 Check resistance of injector of misfiring cylinder (See page SF−21).
NG Replace injector.
OK
Check for open and short in harness and con-
nector between injector and ECM (See page
IN−26).
4 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

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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 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).