Engine General Information and Diagnosis: 1A-90
2 1) Connect the ECM coupler and O2 sensor coupler.
2) Warm up the engine enough.
3) Insert the needle pointed probes to the lead wire coupler.
4) Measure the O2 sensor output voltage between the W/G
wire or W/Bl wire and B/Br wire, in idling condition.
Special tool
(A): 09900–25008 (Multi-circuit tester set)
(B): 09900–25009 (Needle pointed probe set)
Tester knob indication
Voltage ( )
O2 sensor output voltage at idle speed
0.4 V and less
((+) terminal: W/G – (–) terminal: B/Br)
5) If OK, then pinch the PAIR hoses (1) with a proper hose
clamps.
6) Measure the O2 sensor output voltage while holding the
engine speed at 3 000 r/min.
O2 sensor output voltage at 3 000 r/min
0.6 V and more
((+) terminal: W/G – (–) terminal: B/Br)
Is the voltage OK?
• W/G, W/Bl or B/Br
wire open or shorted
to the power source,
or poor “12”, “15” or
“29” connection.
• If wire and
connection are OK,
intermittent trouble or
faulty ECM.
• Recheck each
terminal and wire
harness for open
circuit and poor
connection.
• Replace the ECM
with a known good
one, and inspection it
again. Refer to “ECM
Removal and
Installation in Section
1C (Page 1C-1)”.
Replace the O2 sensor
with a new one. Refer to
“Oxygen Sensor (O2S)
Removal and
Installation in Section
1B (Page 1B-9)”.
Step Action Yes No
(A)
(B)
I822H1110101-01
1
I822H1110102-02
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