P0685 2017 GMC Sierra 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 2017 GMC Sierra 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.
Code P0685 2017 GMC Sierra Description
What are the Possible Causes of the DTC P0685 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 P0685 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.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0685 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.
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Frequently Asked Questions about P0685 2017 GMC Sierra Code
1. What does the OBDII code P0685 mean on a 2017 GMC Sierra?
P0685 indicates that the Engine Control Module (ECM) Power Relay Control Circuit is open, meaning the ECM is not receiving the proper power supply due to an electrical issue.
2. What are the common symptoms of code P0685 on a 2017 GMC Sierra?
Symptoms include the engine not starting, stalling while driving, a check engine light, or intermittent loss of power.
3. What causes the P0685 code to appear on a 2017 GMC Sierra?
Common causes include a faulty ECM power relay, damaged wiring or connectors in the ECM power circuit, a blown fuse, or a malfunctioning ECM.
4. Can I drive my 2017 GMC Sierra with a P0685 code?
Driving with this code is not recommended, as it can lead to engine stalling or prevent the vehicle from starting, potentially leaving you stranded.
5. How do I diagnose the P0685 code on a 2017 GMC Sierra?
Start by checking the ECM power relay, inspecting the wiring and connectors for damage, and testing the fuse associated with the ECM circuit.
6. How do I fix the P0685 code on a 2017 GMC Sierra?
Repairs typically involve replacing a faulty ECM power relay, repairing or replacing damaged wiring, replacing a blown fuse, or, in rare cases, replacing the ECM.
7. How much does it cost to repair the P0685 code on a 2017 GMC Sierra?
Repair costs can vary, but replacing an ECM power relay typically costs $50–$100, while wiring repairs may cost $100–$300 depending on the extent of the damage.
8. Can a dead battery cause a P0685 code on a 2017 GMC Sierra?
A weak or dead battery can indirectly cause issues with the ECM power circuit, but the code is more likely related to a specific relay or wiring fault.
9. How can I prevent a P0685 code from occurring on my 2017 GMC Sierra?
Regularly inspect the electrical components, fuses, and relays in the ECM circuit for signs of wear or damage, and address any issues promptly.
10. Do I need special tools to fix the P0685 code on a 2017 GMC Sierra?
Basic tools like a multimeter and a relay tester can help diagnose the issue, but more advanced repairs may require specialized diagnostic equipment.
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