check engine light TOYOTA T100 1996 Factory Owner's Manual

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DLC3 DI−130
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
The diagnosis system operates in normal mode
during normal vehicle use. It also has a check mode
for technicians to simulate malfunction symptoms
and troubleshoot. Most DTCs use 2 trip detection
logic* to prevent erroneous detection, and ensure
thorough malfunction detection. By switching the
ECM to check mode when troubleshooting, the
technician can cause the MIL to light up for a mal-
function that is only detected once or momentarily
(TOYOTA hand−held tester only).
*2 trip detection logic: When a logic malfunction is
first detected, the malfunction is temporarily stored
in the ECM memory. If the same malfunction is de-
tected again during the 2nd drive test, this 2nd
detection causes the MIL to light up.
The 2 trip repeats the same mode a 2nd time. (How-
ever, the ignition switch must be turned OFF be-
tween the 1st trip and 2nd trip.)
Freeze frame data:
Freeze frame data records the engine condition
when a misfire (DTCs P0300 − P0306) or fuel trim
malfunction (DTCs P0171, P0172) or other mal-
function (first malfunction only), is detected.
Because freeze frame data records the engine
conditions (fuel system, calculator load, engine
coolant temperature, fuel trim, engine speed, ve-
hicle speed, etc.) when the malfunction is detected,
when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the en-
gine warmed up or not, the air−fuel ratio lean or rich,
etc. at the time of the malfunction.
Priorities for troubleshooting:
If troubleshooting priorities for multiple DTCs are given in the
applicable DTC chart, these should be followed.
If no instructions are given troubleshoot DTCs according to the
following priorities.
(1) DTCs other than fuel trim malfunction (DTCs
P0171, P0172), EGR (DTCs P0401, P0402) and
misfire (DTCs P0300 − P0306).
(2) Fuel trim malfunction (DTCs P0171, P0172) and
EGR (DTCs P0401, P0402).
(3) Misfire (DTCs P0300 − P0306).
(b) Check the DLC3
The vehicle’s ECM uses V.P.W. (Variable Pulse Width) for
communication to comply with SAE J1850. The terminal
arrangement of DLC3 complies with SAE J1962 and
matches the V.P.W. format.

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w/o Tachometer
w/ Tachometer
− DIAGNOSTICSENGINE (5VZ−FE)
DI−131
1996 TOYOTA T100 (RM449U) Terminal No.
Connection / Voltage or ResistanceCondition
2Bus  Line / Pulse generationDuring transmission
4Chassis Ground ↔ Body Ground / 1 Ω or lessAlways
5Signal Ground ↔ Body Ground / 1 Ω or lessAlways
16Battery Positive ↔ Body Ground / 9 − 14 VAlways
HINT:
If your display shows ”UNABLE TO CONNECT TO VEHICLE”
when you have connected the cable of the OBD II scan tool or
TOYOTA hand−held tester to DLC3, turned the ignition switch
ON and operated the scan tool, there is a problem on the ve-
hicle 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.
2. INSPECT DIAGNOSIS (Normal Mode)
(a) Check the MIL
(1) The MIL comes on when the ignition switch is turned
ON and the engine is not running.
HINT:
If the MIL does not light up, troubleshoot the combination meter
(See page BE−36).
(2) When the engine started, the MIL should go off. If
the lamp remains on, the diagnosis system has de-
tected a malfunction or abnormality in the system.
(b) Check the DTC.
NOTICE:
TOYOTA hand−held tester only: When the diagnosis sys-
tem is switched from normal mode to check mode, it erases
all DTCs and freezed frame data recorded in normal mode.
So before switching modes, always check the DTCs and
freezed frame data, and note them down.
(1) Prepare the OBD II scan tool (complying with SAE
J1978) or TOYOTA hand−held tester.
(2) Connect the OBD II scan tool or TOYOTA hand−
held tester to the DLC3 at the lower of the instru-
ment panel.
(3) Turn the ignition switch ON and push the OBD II
scan tool or TOYOTA hand−held tester switch ON.
(4) Use the OBD II scan tool or TOYOTA hand−held
tester to check the DTCs and freezed frame data,
note them down. (For operating instructions, see
the OBD II scan tool’s instruction book.)
(5) See page DI−129 to confirm the details of the
DTCs.

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Flashing
ON
OFF
0.13 Seconds
DI−132
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
NOTICE:
When simulating symptoms with an OBD II scan tool (ex-
cluding TOYOTA hand−held tester) to check the DTCs, use
normal mode. For code on the DTC chart subject to ”2 trip
detection logic”, turn the ignition switch OFF after the
symptom is simulated the 1st time. Then repeat the simula-
tion process again. When the problem has been simulated
twice, the MIL lights up and the DTCs are recorded in the
ECM.
3. INSPECT DIAGNOSIS (Check Mode)
HINT:
TOYOTA hand−held tester only:
Compared to the normal mode, the check mode has an in-
creased sensitivity to detect malfunctions.
Furthermore, the same diagnostic items which are detected in
the normal mode can also be detected in the check mode.
(a) Check the DTC.
(1) Initial conditions
Battery positive voltage 11 V or more
Throttle valve fully closed
Transmission in ”P” or ”N” position
Air conditioning switched OFF
(2) Turn the ignition switch OFF.
(3) Prepare the TOYOTA hand−held tester.
(4) Connect the TOYOTA hand−held tester to DLC3 at
the lower of the instrument panel.
(5) Turn the ignition switch ON and push the TOYOTA
hand−held tester switch ON.
(6) Switch the TOYOTA hand−held tester normal mode
to check mode (Check that the MIL flashes.).
(7) Start the engine. (The MIL goes out after the engine
start.)
(8) Simulate the conditions of the malfunction de-
scribed by the customer.
NOTICE:
Leave the ignition switch ON until you have checked the
DTCs, etc.
(9) After simulating the malfunction conditions, use the
TOYOTA hand−held tester diagnosis selector to
check the DTCs and freezed frame data, etc.
HINT:
Take care not to turn the ignition switch OFF. Turning the ignition
switch OFF switches the diagnosis system from check mode to
normal mode. so all DTCs, etc. are erased.
(10) After checking the DTC, inspect the applicable cir-
cuit.

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P21121
A00097
SST
DLC1 E1
TE1
DLC1
− DIAGNOSTICSENGINE (5VZ−FE)
DI−135
1996 TOYOTA T100 (RM449U)
5 Check idle speed.
PREPARATION:
(a) Warm up the engine to normal operating temperature.
(b) Switch off all the accessories.
(c) Switch off air conditioning.
(d) Shift the transmission into ”N” position.
(e) Connect the OBD II scan tool or TOYOTA hand−held tester to the DLC3 on the vehicle.
CHECK:
Use ”CURRENT DATA” to check the idle speed.
OK:
Idle speed: 650 − 750 rpm
NG Proceed to problem symptoms table on page
DI−148.
OK
6 Check ignition timing.
PREPARATION:
(a) Warm up the engine to normal operating temperature.
(b) Shift the transmission into ”N” position.
(c) Keep the engine speed at idle.
(d) Using SST, connect terminals TE1 and E1 of the DLC1.
SST 09843−18020
(e) Using a timing light, connect the tester to the No.1 high−
tension cord.
CHECK:
Check the ignition timing.
OK:
Ignition timing: 8 − 12° BTDC at idle
NG Proceed to page Ignition system and continue
to troubleshoot.
OK
Proceed to problem symptoms table on page
DI−148.

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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.