1.CHECK POWER SUPPLY TO REAR OXYGEN SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from rear oxygen sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between rear oxygen sensor connector and engine ground.
Connector & terminal
(T6) No. 2 (+) — Engine ground (−):
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Is the voltage 10 V or more?
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Repair the power supply line.
NOTE:
In this case, repair the following item:
• Open circuit in harness between A/F, oxygen sensor relay and rear oxygen sensor
• Poor contact of A/F, oxygen sensor relay connector
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2.CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM.
3) Measure the resistance between ECM and oxygen sensor connector.
Connector & terminal
(B136) No. 4 — (T6) No. 1:
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Is the resistance less than 1 Ω?
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Repair the harness and connector.
NOTE:
In this case, repair the following items.
• Open circuit of harness between the ECM and rear oxygen sensor
• Poor contact of coupling connector
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3.CHECK GROUND CIRCUIT FOR ECM.
Measure the resistance of harness between ECM and chassis ground.
Connector & terminal
(B134) No. 5 — Chassis ground:
(B137) No. 1 — Chassis ground:
(B137) No. 2 — Chassis ground:
(B137) No. 3 — Chassis ground:
(B137) No. 7 — Chassis ground:
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Is the resistance less than 5 Ω?
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Repair the harness and connector.
NOTE:
In this case, repair the following item:
• Open circuit of harness between ECM and engine ground
• Poor contact of coupling connector
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4.CHECK REAR OXYGEN SENSOR.
Measure the resistance between rear oxygen sensor terminals.
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Is the resistance between 5 — 7 Ω?
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Repair the poor contact of the ECM connector.
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Replace the rear oxygen sensor. 
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