AutoCodes – GMC – P0686 2016 GMC Sierra

P0686 2016 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 2016 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 151

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 2016 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 2016 GMC Sierra - Engine Control Module Power Relay Control Circuit Low - AutoCodes.com — P0686 2016 GMC Sierra Code - Engine Control Module Power Relay Control Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0686 2016 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 2016 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 2016 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 2016 GMC Sierra code?

Need more information on how to fix the P0686 2016 GMC Sierra code? Get Access to Factory Service Manuals

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 2016 GMC Sierra Code

1. What does the OBDII code P0686 mean on a 2016 GMC Sierra?

P0686 indicates an issue with the Engine Control Module (ECM) Power Relay Control Circuit, specifically that the circuit is reading a low voltage condition.

2. What are the common symptoms of code P0686 in a 2016 GMC Sierra?

Common symptoms include difficulty starting the engine, stalling, reduced engine performance, or the check engine light being illuminated.

3. What causes the P0686 code to appear on a 2016 GMC Sierra?

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

4. Can driving with a P0686 code damage my 2016 GMC Sierra?

While it may not immediately damage the vehicle, this code can cause drivability issues like stalling, which could lead to unsafe driving conditions.

5. How do I diagnose the P0686 code on my 2016 GMC Sierra?

Diagnosis involves inspecting the ECM power relay, checking for damaged wiring or corroded connections, and using a multimeter to test the electrical circuit.

6. How can I fix the P0686 code on a 2016 GMC Sierra?

Repairs may include replacing the ECM power relay, repairing or replacing damaged wiring, or, in rare cases, replacing the ECM itself.

7. How much does it cost to repair the P0686 code on a 2016 GMC Sierra?

The repair cost can vary, but replacing an ECM power relay typically costs $50-$150, while extensive wiring repairs or ECM replacement could cost significantly more.

8. Can a dead battery cause the P0686 code in a 2016 GMC Sierra?

Yes, a low or dead battery can cause voltage issues that may trigger this code. Ensure the battery is fully charged and in good condition.

9. Will clearing the P0686 code with a scan tool fix the problem in my 2016 GMC Sierra?

Clearing the code may temporarily turn off the check engine light, but the underlying issue must be resolved to prevent the code from returning.

10. Is it safe to continue driving a 2016 GMC Sierra with the P0686 code?

Itâ€™s not recommended to drive with this code, as it can cause engine stalling and create unsafe driving conditions. Address the issue as soon as possible.