Code P0685

2006 HONDA CIVIC
80,000 MILES • 1.8L • 4 CYL • 2WD • MANUAL
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MARK87
  • MEMBER
  • 61 POSTS
Hi, just want to know where to start a troubleshooting, i got a code P0685 PCM/ECM power relay control circuit/open.
Apr 3, 2021 at 9:09 AM
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ASEMASTER6371
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 52,796 POSTS
Good afternoon,

Does the check engine light come on with the key on? If the light comes on, then most likely you have power to the ECM. I attached the connector diagram for you to view to verify power to the ECM.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

The code indicates an ECM failure.

Roy
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Apr 4, 2021 at 1:15 PM
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MARK87
  • MEMBER
  • 61 POSTS
Yes, the check engine light comes on with the key on.
Apr 4, 2021 at 8:40 PM
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ASEMASTER6371
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 52,796 POSTS
Okay, then most likely the ECM has failed since the light comes on and you can communicate with it.

Roy
Apr 5, 2021 at 3:35 AM
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MARK87
  • MEMBER
  • 61 POSTS
At times the radio would just switch off and come back on. once it happen the car just shut down, but started after a while. Could it be a bad relay or blown fuse?
Apr 6, 2021 at 5:13 AM
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ASEMASTER6371
  • AUTOMOTIVE REPAIR CONTRIBUTOR
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Site rules are one issue per question. If you start a new question, I would be happy to help you with the radio issue.

Roy
Apr 6, 2021 at 5:20 AM