AutoCodesChevrolet – P0687 2018 Chevrolet Silverado

P0687 2018 Chevrolet Silverado 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 Chevrolet Silverado 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 241
How popular is this code, among other codes? Low
Table of contents Created and updated by William Orellana on Jul 19, 2022
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Code P0687 2018 Chevrolet Silverado 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 Chevrolet Silverado - Engine Control Module Power Relay Control Circuit High - AutoCodes.com
P0687 2018 Chevrolet Silverado Code - Engine Control Module Power Relay Control Circuit High

What are the Possible Causes of the DTC P0687 2018 Chevrolet Silverado?

  • 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 Chevrolet Silverado?

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 Chevrolet Silverado 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 Chevrolet Silverado code?

Need more information on how to fix the P0687 2018 Chevrolet Silverado 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 P0687 2018 Chevrolet Silverado Code

1. What does the OBDII code P0687 mean on a 2018 Chevrolet Silverado?

P0687 indicates an issue with the Engine Control Module (ECM) Power Relay Control Circuit being too high, meaning the ECM isn’t receiving proper power or there’s an electrical fault in the circuit.

2. What are the symptoms of a P0687 code on a 2018 Chevrolet Silverado?

Common symptoms include the engine not starting, intermittent stalling, the check engine light illuminating, and potential loss of communication with the ECM.

3. What causes the P0687 code on a 2018 Chevrolet Silverado?

Possible causes include a faulty ECM power relay, damaged wiring or connectors in the relay circuit, a blown fuse, or a defective ECM.

4. Can I drive my 2018 Chevrolet Silverado with a P0687 code?

Driving with a P0687 code is not recommended, as it could lead to engine stalling or failure to start, potentially leaving you stranded.

5. How do I diagnose the P0687 code on a 2018 Chevrolet Silverado?

Start by visually inspecting the ECM power relay, wiring, and connectors for damage. Check the fuse connected to the ECM circuit and use a multimeter to test for proper voltage and continuity.

6. How do I fix the P0687 code on a 2018 Chevrolet Silverado?

Repairs may include replacing a faulty ECM power relay, repairing or replacing damaged wiring, replacing a blown fuse, or reprogramming/repairing the ECM if necessary.

7. How much does it cost to fix the P0687 code on a 2018 Chevrolet Silverado?

Repair costs depend on the issue but typically range from $50–$200 for a relay replacement and higher if ECM repair or replacement is needed.

8. Can a weak battery cause the P0687 code on a 2018 Chevrolet Silverado?

Yes, a weak or failing battery can lead to low voltage in the ECM power relay circuit, potentially triggering the P0687 code.

9. Will clearing the code fix the P0687 issue on my 2018 Chevrolet Silverado?

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

10. Is the ECM likely to fail with a P0687 code on a 2018 Chevrolet Silverado?

While a faulty ECM is less common, it’s a possibility if all other components in the power relay circuit are functioning correctly.

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