AutoCodes – GMC – P0687 2018 GMC Sierra

P0687 2018 GMC Sierra Code - Engine Control Module Power Relay Control Circuit High

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: P0687 2018 GMC Sierra indicates Engine Control Module Power Relay Control Circuit High.
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 214

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 P0687 2018 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 P0687 2018 GMC Sierra - Engine Control Module Power Relay Control Circuit High - AutoCodes.com — P0687 2018 GMC Sierra Code - Engine Control Module Power Relay Control Circuit High

What does this mean?

What are the Possible Causes of the DTC P0687 2018 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 P0687 2018 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 P0687 2018 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 P0687 2018 GMC Sierra code?

Need more information on how to fix the P0687 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0687 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 P0687 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code P0687 in a 2018 GMC Sierra?

The common symptoms of OBDII code P0687 in a 2018 GMC Sierra include engine stalling, rough idling, loss of power, and in some cases, the vehicle may not start at all.

2. What does the OBDII code P0687 for a 2018 GMC Sierra indicate?

OBDII code P0687 in a 2018 GMC Sierra indicates a problem with the Engine Control Module Power Relay Control Circuit being too high.

3. What are the possible causes of OBDII code P0687 in a 2018 GMC Sierra?

Possible causes of OBDII code P0687 in a 2018 GMC Sierra include a faulty power relay, damaged wiring or connectors in the ECM circuit, or a malfunctioning Engine Control Module itself.

4. How can I diagnose the OBDII code P0687 in my 2018 GMC Sierra?

To diagnose OBDII code P0687 in a 2018 GMC Sierra, you can use an OBDII scanner to read the code, inspect the power relay and related wiring for any damage, and perform continuity tests on the circuit to pinpoint the issue.

5. Can I drive my 2018 GMC Sierra with OBDII code P0687?

It is not recommended to drive your 2018 GMC Sierra with OBDII code P0687, as it can lead to further engine damage or complete failure. It is advisable to address the issue promptly.

6. How can I repair OBDII code P0687 in my 2018 GMC Sierra?

To repair OBDII code P0687 in a 2018 GMC Sierra, you may need to replace the faulty power relay, repair any damaged wiring or connectors, or in some cases, replace the Engine Control Module.

7. Is it necessary to reset the OBDII code P0687 after repairing my 2018 GMC Sierra?

Yes, it is important to clear the OBDII code P0687 after repairing your 2018 GMC Sierra to reset the Check Engine Light and ensure that the issue has been successfully resolved.

8. Can a DIY enthusiast fix OBDII code P0687 in a 2018 GMC Sierra?

Depending on your skill level and access to tools, a DIY enthusiast may be able to fix OBDII code P0687 in a 2018 GMC Sierra by following repair guides and using caution when working with electrical components.

9. What are the long-term effects of ignoring OBDII code P0687 in a 2018 GMC Sierra?

Ignoring OBDII code P0687 in a 2018 GMC Sierra can lead to more severe engine problems, reduced fuel efficiency, and potential safety hazards due to unexpected stalling or loss of power.

10. How can I prevent OBDII code P0687 from occurring in my 2018 GMC Sierra in the future?

To prevent OBDII code P0687 from occurring in your 2018 GMC Sierra in the future, regularly inspect and maintain the power relay and ECM components, address any wiring issues promptly, and avoid overloading electrical circuits in the vehicle.