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Code P0685

Tiny
MARK87
  • MEMBER
  • 2006 HONDA CIVIC
  • 1.8L
  • 4 CYL
  • 2WD
  • MANUAL
  • 80,000 MILES
Hi, just want to know where to start a troubleshooting, I got a code P0685 PCM/ECM power relay control circuit/open.
Saturday, April 3rd, 2021 AT 9:09 AM

5 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 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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Sunday, April 4th, 2021 AT 1:15 PM
Tiny
MARK87
  • MEMBER
  • 61 POSTS
Yes, the check engine light comes on with the key on.
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Sunday, April 4th, 2021 AT 8:40 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay, then most likely the ECM has failed since the light comes on and you can communicate with it.

Roy
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Monday, April 5th, 2021 AT 3:35 AM
Tiny
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?
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Tuesday, April 6th, 2021 AT 5:13 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
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
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Tuesday, April 6th, 2021 AT 5:20 AM

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