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P0686 2017 GMC Sierra Code - Engine Control Module Power Relay Control Circuit Low

Quick Answer

The P0686 code for a 2017 GMC Sierra indicates a problem with the Engine Control Module (ECM) Power Relay Control Circuit being low. Common causes include Faulty ECM power relay, Damaged wiring or connectors in the power relay circuit, Corrosion or poor connections in the power relay circuit. 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
P0686 2017 GMC Sierra indicates Engine Control Module Power Relay Control Circuit Low.
Common causes
Common causes include Faulty ECM power relay, Damaged wiring or connectors in the power relay circuit, Corrosion or poor connections in the power relay circuit.
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 14, 2024
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Code P0686 2017 GMC Sierra Description

The P0686 code for a 2017 GMC Sierra indicates a problem with the Engine Control Module (ECM) Power Relay Control Circuit being low. The ECM is a crucial component of the vehicle's engine management system, responsible for controlling various functions such as fuel injection, ignition timing, and emissions systems. The power relay control circuit is responsible for providing power to the ECM, allowing it to function properly. When this circuit is detected to be operating at a lower voltage than expected, it can lead to a range of issues affecting the vehicle's performance.

OBDII Code P0686 2017 GMC Sierra - Engine Control Module Power Relay Control Circuit Low
P0686 2017 GMC Sierra Code - Engine Control Module Power Relay Control Circuit Low

Common Causes of P0686 2017 GMC Sierra

  1. Faulty ECM power relay
  2. Damaged wiring or connectors in the power relay circuit
  3. Corrosion or poor connections in the power relay circuit
  4. ECM software or hardware issues
  5. Electrical system issues such as a weak battery or alternator

Symptoms of P0686 2017 GMC Sierra

  1. Engine misfires or rough idling
  2. Reduced engine power or acceleration
  3. Check Engine Light illuminated
  4. Difficulty starting the vehicle
  5. Poor fuel efficiency

How to Fix P0686 2017 GMC Sierra

  1. Begin by diagnosing the specific cause of the issue using a diagnostic scanner to read the trouble codes and perform electrical testing on the power relay circuit.
  2. Inspect the ECM power relay and related wiring for any signs of damage, corrosion, or poor connections. Replace any faulty components as needed.
  3. Test the power relay control circuit to ensure it is providing the correct voltage to the ECM. Repair or replace any components that are not functioning properly.
  4. Clear the trouble codes from the ECM's memory and test the vehicle to ensure the issue has been resolved.
  5. If the problem persists, further diagnostics may be required to identify any underlying issues with the ECM or other related components.

Cost to Fix P0686 2017 GMC Sierra

The typical repair costs for addressing a P0686 code on a 2017 GMC Sierra can vary depending on the specific cause of the issue and the extent of the repairs needed. In general, the cost of replacing a faulty ECM power relay or repairing damaged wiring can range from $150 to $300, including parts and labor. However, if the issue is more complex and requires additional diagnostics or ECM replacement, the cost could increase significantly. It is advisable to consult with a qualified mechanic or auto repair shop for a more accurate estimate based on the specific circumstances of your vehicle. Keep in mind that labor rates can vary between different locations and types of repair facilities.

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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 P0686 2017 GMC Sierra Code

1. What does OBDII code P0686 mean for a 2017 GMC Sierra?

P0686 indicates a problem with the Engine Control Module (ECM) Power Relay Control Circuit, specifically a low voltage or signal issue.

2. What are the common symptoms of P0686 in a 2017 GMC Sierra?

Symptoms may include difficulty starting the engine, stalling, reduced engine performance, or the vehicle failing to start entirely.

3. What causes the P0686 code to appear on a 2017 GMC Sierra?

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

4. Can a dead battery trigger the P0686 code on a 2017 GMC Sierra?

Yes, a weak or dead battery can cause low voltage issues that may trigger this code.

5. How do you diagnose the P0686 code on a 2017 GMC Sierra?

Diagnosis typically involves checking the ECM power relay, inspecting the wiring and connectors for damage, and verifying voltage levels in the control circuit.

6. Is it safe to drive a 2017 GMC Sierra with the P0686 code?

Driving with this code is not recommended as it can cause the engine to stall unexpectedly or fail to start, posing safety risks.

7. How do you fix the P0686 code on a 2017 GMC Sierra?

Repairs may include replacing the ECM power relay, repairing or replacing damaged wiring, or addressing issues with the ECM.

8. How much does it cost to repair the P0686 code on a 2017 GMC Sierra?

Repair costs vary but could range from $100 to $500, depending on the exact issue and labor costs.

9. Can a bad ECM cause the P0686 code on a 2017 GMC Sierra?

Yes, a malfunctioning ECM can lead to this code if it fails to properly control the power relay.

10. Will clearing the code fix P0686 on a 2017 GMC Sierra?

Clearing the code may temporarily remove it, but the underlying issue must be resolved to prevent it from returning.

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