Toyota T100 1996 Service Manual page 475

(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).
OX Signal Waveform (Oscilloscope)
1.0 V
0 V
200 msec./Division
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0420) being output?
NO
2 Check heated oxygen sensor (bank 1 sensor 1) (See page DI−172).
OK
3 Check heated oxygen sensor (bank 1 sensor 2) (See page DI−178).
OK
Replace center exhaust pipe (TWC: catalyst)
(See page EM−108).
1996 TOYOTA T100 (RM449U)
DIAGNOSTICS − ENGINE (5VZ−FE)
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.
FI6514
YES Go to relevant DTC chart.
NG Repair or replace.
NG Repair or replace.
DI−211