1.CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Measure the voltage between ECM and chassis ground.
Connector & terminal
(B136) No. 3 (+) — Chassis ground (−):
(B136) No. 2 (+) — Chassis ground (−):
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Is the voltage 10 V or more?
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Repair the short circuit to power in the harness between the ECM and front oxygen (A/F) sensor connector.
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2.CHECK GROUND CIRCUIT FOR ECM.
1) Disconnect the connectors from the ECM.
2) Measure the resistance 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 poor contact of the ECM connector.
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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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