Engine-Codes.com
Engine-Codes – GMC – P0686 GMC

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

Quick Answer

The P0686 diagnostic trouble code for GMC vehicles 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, Blown fuse related to the ECM power supply. 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 GMC 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, Blown fuse related to the ECM power supply.
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 10, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P0686 GMC Description

The P0686 diagnostic trouble code for GMC vehicles indicates a problem with the Engine Control Module (ECM) power relay control circuit being low. The ECM power relay is responsible for supplying power to the ECM, which is a crucial component for the proper functioning of the vehicle's engine management system. When the power relay control circuit is reading low, it means that there is an issue with the power supply to the ECM, which can lead to various performance issues.

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

Common Causes of P0686 GMC

  1. Faulty ECM power relay
  2. Damaged wiring or connectors in the power relay circuit
  3. Blown fuse related to the ECM power supply
  4. Malfunctioning ECM

Symptoms of P0686 GMC

  1. Engine misfires or rough idling
  2. Poor acceleration and reduced power
  3. Check Engine light illuminated on the dashboard
  4. Difficulty starting the engine
  5. Reduced fuel efficiency

How to Fix P0686 GMC

  1. Perform a thorough inspection of the ECM power relay and related wiring for any visible damage or corrosion.
  2. Test the power relay using a multimeter to check for proper voltage supply and continuity.
  3. Check and replace any blown fuses related to the ECM power supply.
  4. If the ECM power relay is faulty, replace it with a new, OEM-quality part.
  5. Clear the error code from the ECM using a diagnostic scanner and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0686 GMC

The typical repair costs for addressing the P0686 code can vary depending on the specific cause of the issue and the cost of replacement parts. In general, the cost of replacing an ECM power relay can range from $50 to $150, while labor costs can range from $80 to $150 per hour. Additional costs may apply if other components need to be replaced or if further diagnostics are required. It's advisable to consult a professional mechanic for an accurate cost estimate based on the specific circumstances of the vehicle in question.

Need more information about the P0686 GMC code?

Need more information on how to fix the P0686 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0686 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC 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.

Frequently Asked Questions about P0686 GMC Code

1. What are the common symptoms of OBDII code P0686 in a GMC vehicle?

The common symptoms of OBDII code P0686 in a GMC vehicle may include engine stalling, rough idling, difficulty starting the engine, and decreased fuel efficiency.

2. What can cause the Engine Control Module Power Relay Control Circuit Low code P0686 in a GMC vehicle?

The P0686 code in a GMC vehicle is usually caused by a faulty engine control module power relay, poor electrical connections, a damaged relay control circuit, or a defective engine control module.

3. How can I diagnose the OBDII code P0686 in my GMC vehicle?

Diagnosing the P0686 code in a GMC vehicle involves using an OBDII scanner to retrieve the trouble code, inspecting the engine control module power relay and related wiring for any damage, and testing the relay control circuit for proper voltage and continuity.

4. Can I still drive my GMC vehicle with the P0686 trouble code?

It is not recommended to drive your GMC vehicle with the P0686 trouble code present, as it can lead to potential engine performance issues and further damage if left unresolved.

5. What are some repair tips for fixing the P0686 code in a GMC vehicle?

Repair tips for addressing the P0686 code in a GMC vehicle include checking and replacing the engine control module power relay if necessary, repairing any damaged wiring or connections, and clearing the trouble code after completing the repairs.

6. How much does it cost to fix the P0686 code in a GMC vehicle?

The cost of fixing the P0686 code in a GMC vehicle can vary depending on the underlying cause of the issue, the cost of parts needed for repair, and labor charges. It is recommended to consult with a professional mechanic for an accurate cost estimate.

7. Can a DIY enthusiast repair the P0686 code in a GMC vehicle?

While some DIY enthusiasts may be able to address the P0686 code by following repair guides and using the necessary tools, it is recommended to consult with a professional mechanic for proper diagnosis and repair to ensure the issue is fully resolved.

8. Will resetting the trouble code make the P0686 issue go away permanently?

Simply resetting the trouble code associated with the P0686 issue may temporarily clear the warning light, but it will not resolve the underlying problem causing the code to reappear. It is essential to diagnose and fix the root cause of the issue to prevent future occurrences.

9. Is the P0686 code specific to GMC vehicles only?

The OBDII code P0686 related to the Engine Control Module Power Relay Control Circuit Low is not specific to GMC vehicles only. It can appear in various makes and models, so it is essential to consult the vehicle's specific diagnostic manual for accurate information.

10. Can a faulty battery or alternator trigger the P0686 trouble code in a GMC vehicle?

While a faulty battery or alternator can cause electrical issues in a vehicle, they are not common triggers for the P0686 trouble code specifically. It is best to focus on diagnosing the engine control module power relay and related components when addressing the P0686 code in a GMC vehicle.

Discuss the causes and fixes for P0686 GMC OBDII Code

Submit a New Comment

Code P0686 GMC comments

No comments found for this page.