1996 TOYOTA T100 sensor

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EGR Gas
Temp.
Sensor
Connector
− DIAGNOSTICSENGINE (5VZ−FE)
DI−205
1996 TOYOTA T100 (RM449U)
7 Check EGR vacuum modulator (See page EC−9).
NG Repair or replace.
OK
8 Check EGR valve (See page EC−9).
NG Repair or replace.
OK
9 Check resistance of EGR gas temp. sensor.
PREPARATION:
(a) Disconnect the EGR gas temp. sensor connector.
(b) Start the engine and warm it up.
(c) Disconnect the VSV connector for EGR.
(d) Race the engine at 4,000 rpm or 3 min.
CHECK:
Measure resistance of the EGR gas temp. sensor while racing
the engine at 4,000 rpm.
OK:
Resistance of EGR gas temp. sensor after 3 min.:
4.3 kΩ or less
HINT:
Resistance: 188.6 ∼ 439.0 kΩ at 20°C (68°F)
NG Replace EGR gas temp. sensor.
OK
Check and replace ECM (See page IN−26).

Downloaded from www.Manualslib.com manuals search engine DI−206
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
DTC P0402 Exhaust Gas Recirculation Flow Excessive
Detected*
*: Only for 2WD models with a load capacity of 0.5 ton and regular cab.
CIRCUIT DESCRIPTION
Refer to DTC P0401 on page DI−196.
DTC No.Detection ItemDTC Detecting ConditionTrouble AreaTrouble Area
P0402
EGR gas temp. sensor value is high during EGR cut−off
when engine is cold (Race engine at about 4,000 rpm
without load so that vacuum is applied to port E)
(2 trip detection logic)EGR valve stuck open
VSV for EGR open malfunction
Open in VSV circuit for EGR
Short in EGR gas temp. sensor circuit
ECM
P0402EGR valve is always open (2 trip detection logic)
WIRING DIAGRAM
Refer to DTC P0401 on page DI−196.
SYSTEM CHECK DRIVING PATTERN
Refer to DTC P0401 on page DI−196.
INSPECTION PROCEDURE
TOYOTA hand−held tester:
1 Connect TOYOTA hand−held tester and read EGR gas temp. value.
PREPARATION:
(a) Connect the TOYOTA hand−held tester to the DLC3.
(b) Turn the ignition switch ON and push the TOYOTA hand−held tester main switch ON.
CHECK:
Read EGR gas temp. on the TOYOTA hand−held tester.
OK:
EGR gas temp.: 159°C (318.2°F) or less (Not immediately after driving)
HINT:
If there is a short circuit, the TOYOTA hand−held tester indicates 159.3°C (318.7°F).
OK Go to step 4.
NG
DI0UY−01

Downloaded from www.Manualslib.com manuals search engine BE6653
P19554
A00048
ON
EGR Gas Temp.
Sensor
2
1ECM
E6 E6
E6 E6
(M/T)(A/T)THG
E25 V
E114 21
922
BE6653
FI7056
P19798
FI7034
A00103
EGR Gas Temp.
SensorECM
THG
E25 V
E1
ON
For M/T
For A/TE6 Connector
E6 Connector
− DIAGNOSTICSENGINE (5VZ−FE)
DI−207
1996 TOYOTA T100 (RM449U)
2 Check for short in harness and ECM.
PREPARATION:
Disconnect the EGR gas temp. sensor connector.
CHECK:
Read EGR gas temp. on the TOYOTA hand−held tester.
OK:
EGR gas temp.: 3.1°C (37.6°F)
OK Replace EGR gas temp. sensor.
NG
3 Check for short in harness or ECM.
PREPARATION:
(a) Remove the right cowl side trim (See page SF−61).
(b) Disconnect the E6 connector of ECM.
HINT:
The EGR gas temp. sensor is disconnected.
CHECK:
Read EGR gas temp. on the TOYOTA hand−held tester.
OK:
EGR gas temp.: 3.1°C (37.6°F)
OK Repair or replace harness or connector.
NG
Check and replace ECM (See pageIN−26).

Downloaded from www.Manualslib.com manuals search engine P24227
EGR Gas
Temp
Sensor
Connector
DI−208
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
4 Check VSV for EGR (See page DI−196, step 5).
OK Check EGR valve (See page EC−9).
NG
5 Check operation of VSV for EGR (See page SF−49).
NG Replace VSV for EGR.
OK
Check for short in harness and connector be-
tween VSV and ECM (See page IN−26).
OBD II scan tool (excluding TOYOTA hand−held tester):
1 Check resistance of EGR gas temp. sensor.
PREPARATION:
Disconnect the EGR gas temp. sensor connector.
CHECK:
Measure resistance between terminals of EGR gas temp. sen-
sor connector.
OK:
Resistance: 2.5 kΩ or more
(Not immediately after driving)
HINT:
If there is short circuit, ohmmeter indicates 200 Ω or less.
NG Replace EGR gas temp. sensor.
OK

Downloaded from www.Manualslib.com manuals search engine − DIAGNOSTICSENGINE (5VZ−FE)
DI−209
1996 TOYOTA T100 (RM449U)
2 Check for short in harness and connector between EGR gas temp. sensor and
ECM (See page IN−26).
NG Repair or replace harness or connector.
OK
3 Check VSV for EGR (See page DI−196, step 5).
OK Check EGR valve (See page EC−9).
NG
4 Check operation of VSV for EGR (See page SF−49).
NG Replace VSV for EGR.
OK
5 Check for short in harness and connector between VSV and ECM
(See page IN−26).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN−26).

Downloaded from www.Manualslib.com manuals search engine FI7081
Waveform of Oxygen Sensor
before CatalystNormal Catalyst Waveform of Oxygen Sensor
after Catalyst
P25762
Engine Speed
2500 − 3000 rpm
Idling
IG SW OFF
Warmed up 3 minutes CheckTime (1)(3)
(4)
(2) DI−210
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
DTC P0420 Catalyst System Efficiency Below Threshold
CIRCUIT DESCRIPTION
The ECM compares the waveform of the oxygen sensor located before the catalyst with the waveform of
the oxygen sensor located after the catalyst to determine whether or not catalyst performance has deterio-
rated.
Air−fuel ratio feedback compensation keeps the waveform of the oxygen sensor before the catalyst repeat-
edly changing back and forth from rich to lean.
If the catalyst is functioning normally, the waveform of the oxygen sensor after the catalyst switches back
and forth between rich and lean much more slowly than the waveform of the oxygen sensor before the cata-
lyst.
But when both waveforms change at a similar rate, it indicates that catalyst performance has deteriorated.


DTC No.DTC Detecting ConditionTrouble Area
P0420
After engine and catalyst are warmed up, and while
vehicle is driven within set vehicle and engine speed range,
waveforms of heated oxygen sensors (bank 1 sensor 1, 2)
have same amplitude
(2 trip detection logic)Three−way catalytic converter
Open or short in heated oxygen sensor (bank 1 sensor 1, 2)
circuit
Heated oxygen sensor (bank 1 sensor 1, 2)
CONFIRMATION ENGINE RACING PATTERN
DI0UZ−01

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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).

Downloaded from www.Manualslib.com manuals search engine S00044
ECM
Vapor Pressure
Sensor
VSV for Vapor
Pressure Sensor
Fuel Tank
Charcoal Canister VSV
for EVAP(1)
(2)
(3) (4)
(5) fig. 1
(6)
DI−212
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
DTC P0441 Evaporative Emission Control System
Incorrect Purge Flow
CIRCUIT DESCRIPTION
The vapor pressure sensor and VSV for vapor pressure sensor are used to detect abnormalities in the evap-
orative emission control system.
The ECM decides whether there is an abnormality in the evaporative emission control system based on the
vapor pressure sensor signal.
DTCs P0441 and P0446 are recorded by the ECM when evaporative emissions leak from the components
within the dotted line in fig. 1 below, or when there is a malfunction in either the VSV for EVAP, the VSV for
vapor pressure sensor, or in the vapor pressure sensor itself.
DTC No.DTC Detecting ConditionTrouble Area
P0441
Pressure in charcoal canister does not drop during purge
control (2 trip detection logic)
Open or short in VSV circuit for EVAP
Open or short in VSV circuit for vapor pressure sensor
Open or short in vapor pressure sensor circuit
VSV for EVAP
VSV for vapor pressure sensor
Vapor pressure sensor
Vacuum hose cracks, holed blocked, damaged or
disconnected ((1), (4), (5) and (6) in fig. 1)
Charcoal canister cracks, holed or damaged
During purge cut−off, pressure in charcoal canister is very
low compared with atmospheric pressure
(2 trip detection logic)
DI9AE−01