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P0685 Ford Code - Powertrain Control Module Power Relay Control Circuit Open

Quick Answer

The P0685 diagnostic trouble code for Ford vehicles indicates a problem with the Powertrain Control Module (PCM) power relay control circuit being open. Common causes include Faulty power relay, Wiring issues or loose connections in the power relay control circuit, Corrosion or damage to the electrical connectors. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0685 Ford indicates Powertrain Control Module Power Relay Control Circuit Open.
Common causes
Common causes include Faulty power relay, Wiring issues or loose connections in the power relay control circuit, Corrosion or damage to the electrical connectors.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 09, 2024
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Code P0685 Ford Description

The P0685 diagnostic trouble code for Ford vehicles indicates a problem with the Powertrain Control Module (PCM) power relay control circuit being open. The PCM is a critical component that controls various functions in the vehicle, such as fuel injection, ignition timing, and emissions control. The power relay control circuit is responsible for providing power to the PCM, allowing it to function properly.

OBDII Code P0685 Ford - Powertrain Control Module Power Relay Control Circuit Open
P0685 Ford Code - Powertrain Control Module Power Relay Control Circuit Open

Common Causes of P0685 Ford

  1. Faulty power relay
  2. Wiring issues or loose connections in the power relay control circuit
  3. Corrosion or damage to the electrical connectors
  4. PCM failure
  5. Electrical system malfunctions

Symptoms of P0685 Ford

  1. Engine misfires or hesitation
  2. Check engine light illuminated
  3. Engine stalling or failure to start
  4. Reduced fuel efficiency
  5. Rough idling or erratic engine performance

How to Fix P0685 Ford

  1. Begin by checking the power relay and its connections for any signs of damage or corrosion. Replace the relay if necessary.
  2. Inspect the wiring in the power relay control circuit for any breaks, frays, or loose connections. Repair or replace damaged wires as needed.
  3. Check the electrical connectors for the PCM and power relay to ensure proper connection and cleanliness. Clean or replace connectors if necessary.
  4. Test the PCM to determine if it is functioning correctly. Replace the PCM if it is found to be faulty.
  5. Clear the diagnostic trouble codes from the vehicle's memory using a scan tool and perform a test drive to verify that the issue has been resolved.

Cost to Fix P0685 Ford

The typical repair costs for addressing a P0685 code can vary depending on the specific cause of the issue and the labor rates at the auto repair shop. In general, replacing a faulty power relay or repairing wiring issues may cost between $100 to $300, including parts and labor. However, if the PCM needs to be replaced, the cost can range from $500 to $1000 or more. It is recommended to consult with a professional mechanic to get an accurate estimate based on the specific circumstances of your vehicle.

What does this mean?

Tech Notes for P0685 Ford

Check all the Engine Control Module (ECM) fuses, if the fuses are OK, then replacing the ECM relay should take care of the problem.

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Information for Specific Ford Models

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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