P0685 2018 GMC Sierra Code - Engine Control Module Power Relay Control Circuit Open
Quick Answer
The P0685 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates that there is an issue with the engine control module (ECM) power relay control circuit being open. Common causes include Faulty ECM power relay, Loose or corroded electrical connections, Blown fuse related to the 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 2018 GMC Sierra indicates Engine Control Module Power Relay Control Circuit Open.
- Common causes
- Common causes include Faulty ECM power relay, Loose or corroded electrical connections, Blown fuse related to the 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 P0685 2018 GMC Sierra Description
The P0685 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates that there is an issue with the engine control module (ECM) power relay control circuit being open. This means that the ECM is not receiving the necessary power signal from the relay, which can lead to various performance issues in the vehicle.
Common Causes of P0685 2018 GMC Sierra
- Faulty ECM power relay
- Loose or corroded electrical connections
- Blown fuse related to the ECM power relay
- Wiring issues in the ECM power relay circuit
- ECM malfunction
Symptoms of P0685 2018 GMC Sierra
- Engine misfires
- Rough idling
- Poor fuel economy
- Stalling
- Check engine light illuminated
How to Fix P0685 2018 GMC Sierra
- Begin by checking the ECM power relay and related fuses for any signs of damage or malfunction.
- Inspect the electrical connections in the ECM power relay circuit for looseness or corrosion, and clean or tighten them as needed.
- Test the ECM power relay using a multimeter to ensure that it is functioning correctly.
- If the ECM power relay is faulty, replace it with a new one following the manufacturer's guidelines.
- Clear the DTC with a scan tool and test drive the vehicle to ensure that the issue has been resolved.
Cost to Fix P0685 2018 GMC Sierra
The typical repair costs for addressing the P0685 DTC on a 2018 GMC Sierra can range from $100 to $300, depending on the specific cause of the issue and the cost of parts and labor. It's important to note that the diagnosis time and labor rates at auto repair shops can vary, so it's advisable to check local rates for a more accurate estimate. Additionally, factors such as location, vehicle make and model, and engine type can also impact the overall repair costs.
Tech Notes for P0685 2018 GMC Sierra
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Frequently Asked Questions about P0685 2018 GMC Sierra Code
What does the OBDII code P0685 mean on a 2018 GMC Sierra?
P0685 indicates an issue with the Engine Control Module (ECM) Power Relay Control Circuit, specifically an open circuit preventing proper power delivery to the ECM.
What are common symptoms of the P0685 code on a 2018 GMC Sierra?
Symptoms include difficulty starting the engine, stalling, reduced engine performance, and the check engine light being illuminated.
What causes the P0685 code on a 2018 GMC Sierra?
Common causes include a faulty ECM power relay, damaged wiring or connectors in the control circuit, or a malfunctioning ECM.
Can I still drive my 2018 GMC Sierra with a P0685 code?
Driving with a P0685 code is not recommended as it can lead to stalling and unreliable engine operation, potentially leaving you stranded.
How do I diagnose the P0685 code on a 2018 GMC Sierra?
Diagnosis typically involves inspecting the ECM power relay, checking for damaged wiring or loose connections, and testing the power circuit with a multimeter.
How do you fix the P0685 code on a 2018 GMC Sierra?
Repairs may involve replacing the ECM power relay, repairing or replacing damaged wiring, and ensuring all connectors are secure and functioning properly.
Will the check engine light turn off automatically after fixing the P0685 code?
The check engine light may turn off after the issue is resolved, but clearing the code with an OBDII scanner is often necessary.
How much does it cost to fix the P0685 code on a 2018 GMC Sierra?
Repair costs vary but typically range from $50 to $150 for parts (such as a new relay) and additional labor costs depending on the complexity of the issue.
Can a weak battery cause the P0685 code on a 2018 GMC Sierra?
Yes, a weak or failing battery can contribute to insufficient power delivery to the ECM, potentially triggering the P0685 code.
Is replacing the ECM necessary to fix the P0685 code on a 2018 GMC Sierra?
Replacing the ECM is rare and only necessary if all other components, including the relay and wiring, are confirmed to be functioning properly.
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