AutoCodes – GMC – P0686 2017 GMC Sierra

P0686 2017 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 2017 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 238

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 2017 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 2017 GMC Sierra - Engine Control Module Power Relay Control Circuit Low - AutoCodes.com — P0686 2017 GMC Sierra Code - Engine Control Module Power Relay Control Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0686 2017 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 2017 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 2017 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 2017 GMC Sierra code?

Need more information on how to fix the P0686 2017 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 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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