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P0685 2014 Chevrolet Silverado Code - Engine Control Module Power Relay Control Circuit Open

Quick Answer

The P0685 diagnostic trouble code (DTC) indicates an issue with the Engine Control Module (ECM) power relay control circuit. Common causes include Faulty ECM Power Relay: A malfunctioning relay can prevent power from reaching the ECM, Wiring Issues: Damaged, frayed, or corroded wiring in the power relay circuit can create an open circuit, Defective ECM: A failure within the ECM itself can lead to power control issues. 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 2014 Chevrolet Silverado indicates Engine Control Module Power Relay Control Circuit Open.
Common causes
Common causes include Faulty ECM Power Relay: A malfunctioning relay can prevent power from reaching the ECM, Wiring Issues: Damaged, frayed, or corroded wiring in the power relay circuit can create an open circuit, Defective ECM: A failure within the ECM itself can lead to power control issues.
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 Oct 21, 2024
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Code P0685 2014 Chevrolet Silverado Description

The P0685 diagnostic trouble code (DTC) indicates an issue with the Engine Control Module (ECM) power relay control circuit. Specifically, this code signifies that the ECM is not receiving power due to an open circuit in the relay control. The ECM is a critical component of the vehicle's engine management system, responsible for monitoring and controlling various engine functions to optimize performance, fuel efficiency, and emissions. When the power relay circuit is open, the ECM cannot operate, leading to a range of performance issues.

OBDII Code P0685 2014 Chevrolet Silverado - Engine Control Module Power Relay Control Circuit Open
P0685 2014 Chevrolet Silverado Code - Engine Control Module Power Relay Control Circuit Open

Common Causes of P0685 2014 Chevrolet Silverado

  1. Faulty ECM Power Relay: A malfunctioning relay can prevent power from reaching the ECM.
  2. Wiring Issues: Damaged, frayed, or corroded wiring in the power relay circuit can create an open circuit.
  3. Defective ECM: A failure within the ECM itself can lead to power control issues.
  4. Poor Ground Connections: Inadequate grounding can disrupt the electrical flow to the ECM.
  5. Moisture or Contamination: Water intrusion or dirt can affect electrical connections, leading to circuit failures.

Symptoms of P0685 2014 Chevrolet Silverado

  1. No Start Condition: The vehicle may fail to start due to the ECM not receiving power.
  2. Engine Stalling: Intermittent power loss to the ECM can cause the engine to stall while driving.
  3. Reduced Engine Performance: The vehicle may enter limp mode, resulting in decreased power and responsiveness.
  4. Check Engine Light: The illumination of the check engine light on the dashboard, indicating a fault in the engine management system.
  5. Electrical Issues: Other electrical components may exhibit erratic behavior due to insufficient power supply from the ECM.

How to Fix P0685 2014 Chevrolet Silverado

  1. Visual Inspection: Begin with a thorough inspection of the wiring and connectors associated with the ECM power relay circuit for any visible damage or corrosion.
  2. Test the Power Relay: Use a multimeter to check the functionality of the ECM power relay. Replace it if it is found to be defective.
  3. Check Wiring and Connections: Inspect the wiring for continuity and integrity. Repair or replace any damaged wires or connectors.
  4. Test the ECM: If the relay and wiring are intact, test the ECM for proper operation. If it is found to be faulty, replacement may be necessary.
  5. Clear Codes and Test Drive: After repairs, clear the DTCs and perform a test drive to ensure the issue has been resolved and the code does not reappear.

Cost to Fix P0685 2014 Chevrolet Silverado

The cost to repair a P0685 code can vary widely based on the specific issue and the labor rates in your area. On average, you might expect to pay between $150 and $400 for parts and labor. This estimate includes the cost of a new power relay, any necessary wiring repairs, and labor charges. Labor rates typically range from $80 to $150 per hour, depending on the shop's location and whether it is an independent or dealership service center. In metropolitan areas, rates may be higher, while independent shops often offer more competitive pricing. It is advisable to obtain quotes from local repair shops for a more accurate estimate tailored to your specific situation.

What does this mean?

Tech Notes for P0685 2014 Chevrolet Silverado

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

Need more information about the P0685 2014 Chevrolet Silverado code?

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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.

Frequently Asked Questions about P0685 2014 Chevrolet Silverado Code

What does the OBDII code P0685 mean for a 2014 Chevrolet Silverado?

Code P0685 indicates that the Engine Control Module (ECM) Power Relay Control Circuit is open, meaning the ECM is not receiving the proper power supply.

What are the common symptoms of code P0685 in a 2014 Chevrolet Silverado?

Symptoms include difficulty starting the engine, a no-start condition, reduced engine performance, and the Check Engine Light being illuminated.

What causes the P0685 code in a 2014 Chevrolet Silverado?

Common causes include a faulty ECM power relay, damaged wiring or connectors in the control circuit, or a malfunctioning ECM.

Can a bad battery cause the P0685 code?

Yes, a weak or failing battery can contribute to this code if it disrupts the power supply to the ECM.

How do you diagnose the P0685 code in a 2014 Chevrolet Silverado?

Diagnosis involves inspecting the ECM power relay, checking the wiring and connectors for damage or corrosion, and testing the relay and circuit for proper operation.

Can I drive my 2014 Chevrolet Silverado with the P0685 code?

Driving with this code is not recommended, as it can lead to engine failure or a no-start condition, potentially leaving you stranded.

How is the P0685 code repaired on a 2014 Chevrolet Silverado?

Repairs typically involve replacing the ECM power relay, repairing damaged wiring or connectors, or, in rare cases, replacing the ECM.

How much does it cost to fix the P0685 code on a 2014 Chevrolet Silverado?

Repair costs vary but typically range from $50 to $200 for parts and labor, depending on the specific issue and location.

Can a P0685 code trigger other codes in the ECM?

Yes, an open circuit in the ECM power relay can cause communication errors, leading to additional codes being stored in the ECM.

How can I prevent the P0685 code from occurring?

Regular maintenance, such as inspecting wiring and connectors for damage and ensuring the battery is in good condition, can help prevent this code.

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