AutoCodes – GMC – P0686 2014 GMC Sierra

P0686 2014 GMC Sierra Code - Engine Control Module Power Relay Control Circuit Low

Quick Answer

The powertrain relay is a normally open relay. Common causes include Weak battery, Low voltage while cranking, Faulty Engine Control Module (ECM) power relay. 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 2014 GMC Sierra indicates Engine Control Module Power Relay Control Circuit Low.
Common causes: Common causes include Weak battery, Low voltage while cranking, Faulty Engine Control Module (ECM) power relay.
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.

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Code Popularity 195

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 19, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0686 2014 GMC Sierra Description

The powertrain relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature contact at all times. The Engine Control Module (ECM) supplies the ground path to the relay coil control circuit via an internal integrated circuit called an Output Driver Module (ODM). The ODM output control is configured to operate as a low side driver for the powertrain relay. The ODM for the powertrain relay also incorporates a fault detection circuit, which is continuously monitored by the ECM. When the ECM commands the powertrain relay ON, ignition 1 voltage is supplied to the ECM, and to several additional circuits.

OBDII Code P0686 2014 GMC Sierra - Engine Control Module Power Relay Control Circuit Low - AutoCodes.com — P0686 2014 GMC Sierra Code - Engine Control Module Power Relay Control Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0686 2014 GMC Sierra?

Weak battery
Low voltage while cranking
Faulty Engine Control Module (ECM) power relay
ECM power relay harness is open or shorted
ECM power relay circuit poor electrical connection
Blown ECM fuse
Faulty ECM

How to Fix the DTC P0686 2014 GMC Sierra?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0686 2014 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0686 2014 GMC Sierra code?

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Need Help with the 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 P0686 2014 GMC Sierra Code

1. What does the OBDII code P0686 mean on a 2014 GMC Sierra?

P0686 indicates an issue with the Engine Control Module (ECM) Power Relay Control Circuit being too low, suggesting a possible electrical fault or relay problem.

2. What are the common symptoms of code P0686 in a 2014 GMC Sierra?

Symptoms may include difficulty starting the engine, stalling, reduced performance, or a complete no-start condition along with an illuminated check engine light.

3. What causes the P0686 code to appear in a 2014 GMC Sierra?

Common causes include a faulty ECM power relay, damaged wiring, corroded or loose electrical connections, or a malfunctioning ECM.

4. Can I drive my 2014 GMC Sierra with the P0686 code?

Driving with this code is not recommended, as it can lead to unreliable engine performance or cause the vehicle to stall unexpectedly.

5. How do I diagnose the P0686 code in my GMC Sierra?

Start by inspecting the ECM power relay, checking for damaged wiring or corroded connections, and testing the relay and circuit for proper voltage and continuity.

6. How do I fix the P0686 code on a 2014 GMC Sierra?

Repairs may involve replacing the ECM power relay, repairing or replacing damaged wiring, cleaning corroded connections, or, in rare cases, replacing the ECM.

7. How much does it cost to repair a P0686 code on a GMC Sierra?

Repair costs vary depending on the cause but generally range from $100 to $500, with relay replacement being on the lower end and ECM replacement costing more.

8. Can a weak battery cause the P0686 code on a GMC Sierra?

Yes, a weak or failing battery can cause voltage issues that may trigger this code. Ensure the battery is in good condition before further diagnosis.

9. Does the P0686 code mean my ECM is bad?

Not necessarily. While a faulty ECM is possible, the issue is more commonly related to the power relay or wiring. Thorough diagnosis is essential.

10. Can I clear the P0686 code without fixing it on my 2014 GMC Sierra?

Clearing the code without addressing the root cause may temporarily turn off the check engine light, but the issue will likely return until properly repaired.