1996 TOYOTA T100 check engine light

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DI−140
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
DIAGNOSTIC TROUBLE CODE CHART
SAE CONTROLLED
HINT:
Parameters listed in the chart may not be exactly the same as your reading due to the type of instrument
or other factors.
If a malfunction code is displayed during the DTC check in check mode, check the circuit for that code listed
in the table below. For details of each code, turn to the page referred to under the ’’See Page ’’ for the respec-
tive ’’DTC No.’’ in the DTC chart.
DTC No.
(See Page)Detection ItemTrouble AreaMIL*Memory
P0100
(DI−149)Mass Air Flow Circuit
MalfunctionOpen or short in mass air flow meter circuit
Mass air flow meter
ECM

P0101
(DI−153)Mass Air Flow Circuit
Range/Performance
Problem
Mass air flow meter
P0110
(DI−154)Intake Air Temp. Circuit
MalfunctionOpen or short in intake air temp. sensor circuit
Intake air temp. sensor
ECM

P0115
(DI−158)Engine Coolant Temp. Circuit
MalfunctionOpen or short in engine coolant temp. sensor circuit
Engine coolant temp. sensor
ECM

P0116
(DI−162)Engine Coolant Temp. Circuit
Range/Performance ProblemEngine coolant temp. sensor
Cooling system
P0120
(DI−163)Throttle/Pedal Position
Sensor/Switch ”A” Circuit
MalfunctionOpen or short in throttle position sensor circuit
Throttle position sensor
ECM

P0121
(DI−168)Throttle/Pedal Position
Sensor/Switch ”A” Circuit
Range/Performance Problem
Throttle position sensor
P0125
(DI−169)Insufficient Coolant Temp. for
Closed Loop Fuel ControlOpen or short in heated oxygen sensor (bank 1 sensor 1)
circuit
Heated oxygen sensor (bank 1 sensor 1)

P0130
(DI−172)Heated Oxygen Sensor Circuit
Malfunction (Bank 1 Sensor 1)Heated oxygen sensor
Fuel trim malfunction
P0133
(DI−175)Heated Oxygen Sensor Circuit
Slow Response
(Bank 1 Sensor 1)
Heated oxygen sensor
P0135
(DI−176)Heated Oxygen Sensor Heater
Circuit Malfunction
(Bank 1 Sensor 1)Open or short in heater circuit of heated oxygen sensor
Heated oxygen sensor
ECM

P0136
(DI−178)Heated Oxygen Sensor Circuit
Malfunction
(Bank 1 Sensor 2)
Heated oxygen sensor
P0141
(DI−176)Heated Oxygen Sensor Heater
Circuit Malfunction
(Bank 1 Sensor 2)
Same as DTC No. P0135
*:  MIL lights up

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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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− 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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Vehicle Speed
70 ∼ 90 km/h
(43 ∼ 56 km/h)
Idling
IG SW OFF(2)
(1)(3)
(4)(5)
(6)
Warm up 3 ∼ 5 min. 3 ∼ 5 min. 2 min. 2 min.
Time
− DIAGNOSTICSENGINE (5VZ−FE)
DI−197
1996 TOYOTA T100 (RM449U)
SYSTEM CHECK DRIVING PATTERN
(1) Connect the OBD II scan tool or TOYOTA hand−held tester to the DLC3.
(2) Start and warm up the engine with all the accessories switched OFF.
(3) Run the vehicle at 70 − 90 km/h (43 − 56 mph) for 3 min. or more.
(4) Idle the engine for about 2 min.
(5) Do steps (3) and (4) again.
(6) Check the ”READINESS TESTS” mode on the OBD II scan tool or TOYOTA hand−held tester.
If ”COMPL” is displayed and the MIL does not light up, the system is normal.
If ”INCMPL” is displayed and the MIL does not light up, run the vehicle step (5) from some time and check
it.
HINT:
”INCMPL” is displayed when either condition (a) or (b) exists:
(a) The system check is incomplete.
(b) There is a malfunction in the system.
If there is a malfunction in the system, the MIL will light up after steps (2) to (5) above are done.

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OX Signal Waveform (Oscilloscope)
1.0 V
0 V
200 msec./Division
− DIAGNOSTICSENGINE (5VZ−FE)
DI−211
1996 TOYOTA T100 (RM449U)
(1) Connect the TOYOTA hand−held tester to the DLC3, or connect the probe of the oscilloscope between
terminals OX1, OX2 and E1 of ECM.
(2) Start engine and warm it up with all accessories switched OFF until water temp. is stable.
(3) Race the engine at 2500 − 3000 rpm for about 3 min.
(4) After confirming that the waveform of the heated oxygen sensor, bank 1 sensor 1 (OX1), oscillate around
0.5 V during feedback to the ECM, check the waveform of the heated oxygen sensor bank 1 sensor 2 (OX2).
HINT:
If there is a malfunction in the system, the waveform of the
heated oxygen sensor bank 1 sensor 2 (OX2) is almost the
same as that of the heated oxygen sensor bank 1 sensor 1
(OX1) on the left.
There are some cases where, even though a malfunction
exists, the MIL may either light up or not light up.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0420) being output?
YES Go to relevant DTC chart.
NO
2 Check heated oxygen sensor (bank 1 sensor 1) (See page DI−172).
NG Repair or replace.
OK
3 Check heated oxygen sensor (bank 1 sensor 2) (See page DI−178).
NG Repair or replace.
OK
Replace center exhaust pipe (TWC: catalyst)
(See page EM−108).

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Vehicle Brought to Workshop
Customer Problem Analysis
Check DTC and Freezes Frame Data (Precheck)
Record or Print DTC and Freezed Frame Data P.
DI−265
Clear DTC and Freezed Frame Data P. DI−265
Visual Inspection
Setting the Check Mode Diagnosis P.
DI−265
1
Items insideare titles of pages in this manual, with the
page number indicated in the bottom portion. See the indicated
pages for detailed explanations.
P.
DI−264
Connect an OBD II scan tool or TOYOTA hand−held tester to DLC3
If the display shows ”UNABLE TO CONNECT TO VEHICLE” when you have connected the
scan tool/TOYOTA hand−held tester, inspect DLC3 P.
DI−265
2
3
4
5
6
symptom does not occur
Problem Symptom Confirmation8
7Symptom Simulation
P.
IN−16symptom occur
DTC Check
P. DI−265OK Code
11Preliminary Check
P.
DI−265
DTC Chart
P.
DI−276
Mechanical System Tests
P.
DI−265
Manual Shifting Test
P.
DI−265 OK
OK
Chapter 1
(Electronic)Chapter 2
(On−Vehicle)OKChapter 3
(Off−Vehicle)OK Problem Symptoms table
P. DI−282
Circuit
Inspection O/D Cancel Signal Check
 Stop Light Signal Check
NG
Parts Inspection
NG
NGNG
Identification of ProblemRepairConfirmation TestEnd
NG
NG
12
NG13
14
1516
17 9
10
P. DI−282
P. DI−286 to DI−316
18
P. DI−282P. DI−282
− DIAGNOSTICSAUTOMATIC TRANSMISSION
DI−263
520 Author: Date:
1996 TOYOTA T100 (RM449U)
AUTOMATIC TRANSMISSION
HOW TO PROCEED WITH TROUBLESHOOTING
Troubleshoot in accordance with the procedure on the following page.

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w/o Tachometer
w/ Tachometer
DI0VF−02
Q08498
TOYOTA Hand−Held Tester
DLC3
− DIAGNOSTICSAUTOMATIC TRANSMISSION
DI−265
1996 TOYOTA T100 (RM449U)
PRE−CHECK
1. DIAGNOSIS SYSTEM
(a) Description
When troubleshooting OBD II vehicles, the only dif-
ference from the usual troubleshooting procedure
is that you connect to the vehicle an OBD II scan
tool complying with SAE J1978 or TOYOTA hand−
held tester, and read off various data output from
the vehicle’s ECM.
OBD II regulations require that the vehicle’s on−
board computer lights up the Malfunction Indicator
Lamp (MIL) on the instrument panel when the com-
puter detects a malfunction in the computer itself or
in drive system components which affect vehicle
emissions. In addition to the MIL lighting up when
a malfunction is detected, the applicable DTCs pre-
scribed by SAE J2012 are recorded in the ECM
memory.
(3RZ−FE: See page DI−13)
(5VZ−FE: See page DI−140)
If the malfunction only occurs in 3 trips, the MIL goes off but the
DTCs remain recorded in the ECM memory.
To check the DTCs, connect an OBD II scan tool or
TOYOTA hand−held tester to DLC3 on the vehicle.
The OBD II scan tool or TOYOTA hand−held tester
also enables you to erase the DTCs and check
freeze frame data and various forms of engine data
(For instruction book).
DTCs include SAE controlled codes and Manufac-
turer controlled codes.
SAE controlled codes must be set as prescribed by
the SAE, while Manufacturer controlled codes can
be set freely by the manufacturer within the pre-
scribed limits (See DTC chart on page DI−276).

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DI−266
− DIAGNOSTICSAUTOMATIC TRANSMISSION
1996 TOYOTA T100 (RM449U)
The diagnosis system operates in normal mode
during normal vehicle use, and also has a check
mode for technicians to simulate malfunction symp-
toms and perform troubleshooting. Most DTCs use
2 trip detection logic(*) to prevent erroneous detec-
tion. By switching the ECM to check mode when
troubleshooting, the technician can cause the MIL
to light up and for a malfunction that is only detected
once or momentarily (TOYOTA hand−held tester)
(See page DI−265).
*2 trip detection logic:
When a logic malfunction is first detected, the mal-
function is temporarily stored in the ECM memory.
If the same malfunction is detected again during the
2nd test drive, this 2nd detection causes the MIL to
light up.
(b) Inspect the DLC3.
The vehicle’s ECM uses the V.P.W. (Variable Pulse Width)
for communication to comply with SAE J1850. The termi-
nal arrangement of DLC3 complies with SAE J1962 and
matches the V.P.W. format.
Terminal No.Connection / Voltage or ResistanceCondition
2Bus  Line / Pulse generationDuring communication
4Chassis Ground ↔ Body / 1 Ω or lessAlways
5Signal Ground ↔ Body / 1 Ω or lessAlways
16Battery Positive ↔ Body / 9 − 14 VAlways
HINT:
If your display shows ”UNABLE TO CONNECT TO VEHICLE”
when you have connected the cable of OBD II scan tool or TOY-
OTA hand−held tester to DLC3, turned the ignition switch ON
and operated the scan tool, there is a problem on the vehicle
side or tool side.
If communication is normal when the tool is connected to
another vehicle, inspect DLC3 on the original vehicle.
If communication is still not possible when the tool is con-
nected to another vehicle, the problem is probably in the
tool itself, so consult the Service Department listed in the
tool’s instruction manual.