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P0685 2015 Chevrolet Silverado Code - Engine Control Module Power Relay Control Circuit Open

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: P0685 2015 Chevrolet Silverado indicates Engine Control Module Power Relay Control Circuit Open.
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 376

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
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0685 2015 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 P0685 2015 Chevrolet Silverado - Engine Control Module Power Relay Control Circuit Open - AutoCodes.com — P0685 2015 Chevrolet Silverado Code - Engine Control Module Power Relay Control Circuit Open

What does this mean?

What are the Possible Causes of the DTC P0685 2015 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 P0685 2015 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 does this mean?

Code Tech Notes

Check all the Engine Control Module (ECM) fuses, if the fuses are OK, then replacing the ECM relay should take care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0685 2015 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 P0685 2015 Chevrolet Silverado code?

Need more information on how to fix the P0685 2015 Chevrolet Silverado code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0685 2015 Chevrolet Silverado 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 P0685 2015 Chevrolet Silverado Code

1. What does the OBDII code P0685 mean on a 2015 Chevrolet Silverado?

P0685 indicates an issue with the Engine Control Module (ECM) Power Relay Control Circuit, often due to an electrical fault or open circuit.

2. What are the common symptoms of code P0685 in a 2015 Silverado?

Symptoms include engine stalling, failure to start, intermittent power loss, or an illuminated check engine light.

3. What causes the P0685 code on a 2015 Chevrolet Silverado?

The common causes include a faulty ECM power relay, damaged wiring or connectors in the relay circuit, a blown fuse, or, in rare cases, a failing ECM.

4. Can a faulty ECM power relay trigger the P0685 code?

Yes, a defective ECM power relay can prevent proper power delivery to the ECM, resulting in this code.

5. How is P0685 diagnosed on a 2015 Silverado?

A technician will inspect the ECM power relay, check for open or damaged wires, test the relay circuit, and verify proper voltage and ground connections.

6. Is it safe to drive a 2015 Chevrolet Silverado with a P0685 code?

Driving with this code is not recommended, as it can lead to engine stalling or failure to start, which may leave you stranded.

7. How do you fix the P0685 code on a 2015 Silverado?

Repairs may include replacing the ECM power relay, repairing damaged wiring or connectors, replacing a blown fuse, or addressing ECM issues if necessary.

8. What tools are needed to troubleshoot P0685 on a 2015 Chevrolet Silverado?

Basic tools include a multimeter, a scan tool, and potentially a relay tester to diagnose the issue accurately.

9. Can a blown fuse cause the P0685 code in a 2015 Silverado?

Yes, a blown fuse in the ECM power circuit can disrupt power flow and trigger this code.

10. How much does it cost to repair the P0685 code on a 2015 Chevrolet Silverado?

Repair costs vary but typically range from $50 to $200 depending on whether the issue is a relay, wiring, or ECM replacement.

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