1996 TOYOTA T100 check engine

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

Downloaded from www.Manualslib.com manuals search engine FI6514
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 S00594
Vapor Pressure SensorECM
From
Battery
From
IG SwitchII
IDIM12H
2D2C
2BE7
E6
E7
E6
E6 3
92
25
12 3
AA2 1
8 2 1 VSV (for EVAP)
VSV
(for Vapor
Pressure Sensor) LG
W−B B−O BP L−R
BR13
22 3
2
1
10
IGN
Instrument
Panel J/BDriver Side J/B
EFI Relay
EB
J/B
No.3VC
E2
E1
E01
E01 TPC EVP 1PTNK
BR
EFI
A
12 LGW−L 3
B−O5 V
− DIAGNOSTICSENGINE (5VZ−FE)
DI−213
1996 TOYOTA T100 (RM449U)
WIRING DIAGRAM
INSPECTION PROCEDURE
TOYOTA hand−held tester:
1 Check VSV connector for EVAP, VSV connector for vapor pressure sensor and
vapor pressure sensor connector for looseness and disconnection.
NG Repair or connect VSV or sensor connector.
OK

Downloaded from www.Manualslib.com manuals search engine BE6653S00564A06382
ON
E2(−)VC(+)
DI−214
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
2 Check vacuum hose between throttle body and VSV for EVAP, VSV for EVAP and
charcoal canister, charcoal canister and VSV for vapor pressure sensor, VSV for
vapor pressure sensor and vapor pressure sensor.
CHECK:
(a) Check that the vacuum hose is connected correctly.
(b) Check the vacuum hose for looseness and disconnection.
(c) Check the vacuum hose for cracks, hole, damage and blockage.
NG Repair or replace.
OK
3 Check voltage between terminals VCC and E2 of ECM connector.
PREPARATION:
(a) Remove the glove compartment (See page SF−61).
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminals VC and E2 of ECM con-
nector.
OK:
Voltage: 4.5 − 5.5 V
NG Check and replace ECM (See page IN−26).
OK

Downloaded from www.Manualslib.com manuals search engine BE6653S00568P2497
6S0 00 47A06383
E2(−) PTNK(+)
ON
Vacuum
− DIAGNOSTICSENGINE (5VZ−FE)
DI−215
1996 TOYOTA T100 (RM449U)
4 Check voltage between terminals PTNK and E2 of ECM connector.
PREPARATION:
(a) Remove the glove compartment (See page SF−61).
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminals PTNK and E2 of ECM con-
nector.
(1) Disconnect the vacuum hose from the vapor pres-
sure sensor.
(2) Using the MITYVAC (Hand−Held Vacuum Pump),
apply a vacuum to the vapor pressure sensor.
NOTICE:
The vacuum applied to the vapor pressure sensor must be
less than 66.7 kPa (500 mmHg, 19.7 in. Hg).
OK:
(1) Voltage: 2.9 − 3.7 V
(2) Voltage: 0.5 V or less
OK Go to step 6.
NG
5 Check for open and short in harness and connector between vapor pressure
sensor and ECM (See page
IN−26).
NG Repair or replace harness or connector.
OK
Replace vapor pressure sensor.

Downloaded from www.Manualslib.com manuals search engine S05710S05711
A00784
VSV is OFF VSV is ON
DI−216
− DIAGNOSTICSENGINE (5VZ−FE)
1996 TOYOTA T100 (RM449U)
6 Check the purge flow.
PREPARATION:
(a) Connect the TOYOTA hand−held tester to the DLC3.
(b) Select the ”ACTIVE TEST” mode on the TOYOTA hand−
held tester.
(c) Disconnect the VSV vacuum hose for EVAP from the
charcoal canister.
(d) Start the engine.
CHECK:
When the VSV for the EVAP is operated by the TOYOTA
hand−held tester, check whether the disconnected hose ap-
plies suction to your finger.
OK:
VSV is ON:
Disconnected hose applies suction to your finger.
VSV is OFF:
Disconnected hose applies no suction to your finger.
OK Go to step 10.
NG
7 Check vacuum hose between throttle body and VSV for EVAP, VSV for EVAP and
charcoal canister.
CHECK:
(a) Check that the vacuum hose is connected correctly.
(b) Check the vacuum hose for looseness and disconnection.
(c) Check the vacuum hose for cracks, hole, damage and blockage.
NG Repair or replace.
OK