AutoCodes – Chevrolet – P0685 2016 Chevrolet Silverado

P0685 2016 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 2016 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 737

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 2016 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 2016 Chevrolet Silverado - Engine Control Module Power Relay Control Circuit Open - AutoCodes.com — P0685 2016 Chevrolet Silverado Code - Engine Control Module Power Relay Control Circuit Open

What does this mean?

What are the Possible Causes of the DTC P0685 2016 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 2016 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 2016 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 2016 Chevrolet Silverado code?

Need more information on how to fix the P0685 2016 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 P0685 2016 Chevrolet Silverado Code

1. What does the OBDII code P0685 mean on a 2016 Chevrolet Silverado?

P0685 indicates an issue with the Engine Control Module (ECM) Power Relay Control Circuit, which could mean the circuit is open or not functioning properly.

2. What are the symptoms of code P0685 in a 2016 Chevrolet Silverado?

Common symptoms include the engine failing to start, stalling, poor performance, or the Check Engine Light being illuminated.

3. What causes the P0685 code to appear on my Silverado?

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

4. Can I drive my 2016 Silverado with a P0685 code?

Driving with this code is not recommended, as it can cause the engine to stall unexpectedly or fail to start altogether.

5. How do I fix the P0685 code on my 2016 Chevrolet Silverado?

Repairs may involve replacing a faulty ECM power relay, repairing or replacing damaged wiring, cleaning corroded connectors, or in some cases, replacing the ECM.

6. How much does it cost to repair a P0685 code on a 2016 Silverado?

Repair costs can vary, but replacing the ECM power relay typically costs $50â€“$150. Wiring or ECM repairs can be more expensive, depending on the extent of the damage.

7. How can I diagnose the P0685 code on my Silverado?

Diagnosis involves checking the ECM power relay, inspecting the circuit for damaged wiring or corrosion, and testing the ECM for proper function using a multimeter or scan tool.

8. Can a weak battery cause the P0685 code on a 2016 Silverado?

Yes, a weak or failing battery can cause voltage drops that may trigger this code, so itâ€™s important to ensure the battery is in good condition.

9. Does the P0685 code always indicate a faulty ECM on a Silverado?

No, it does not always mean the ECM is faulty. The issue is often related to the power relay, wiring, or connectors, so these should be checked first.

10. Can I clear the P0685 code without fixing the issue?

Clearing the code without addressing the root cause will only temporarily remove it. The issue will likely return until properly repaired.