P0685 GMC Code - Engine Control Module Power Relay Control Circuit Open
Quick Answer
The P0685 code for GMC vehicles indicates a problem with the Engine Control Module (ECM) Power Relay Control Circuit being open. Common causes include Damaged wiring or connectors in the power relay control circuit, Faulty ECM power relay, Blown fuse related to the ECM power supply. 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 GMC indicates Engine Control Module Power Relay Control Circuit Open.
- Common causes
- Common causes include Damaged wiring or connectors in the power relay control circuit, Faulty ECM power relay, Blown fuse related to the ECM power supply.
- 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 GMC Description
The P0685 code for GMC vehicles indicates a problem with the Engine Control Module (ECM) Power Relay Control Circuit being open. The Engine Control Module, also known as the ECM or PCM (Powertrain Control Module), controls various functions in the vehicle, including the engine's performance, fuel delivery, and emissions systems. The power relay control circuit is responsible for providing power to the ECM, allowing it to function properly.
Common Causes of P0685 GMC
- Damaged wiring or connectors in the power relay control circuit
- Faulty ECM power relay
- Blown fuse related to the ECM power supply
- Malfunctioning ECM
- Corrosion or poor connections in the electrical system
Symptoms of P0685 GMC
- Engine misfires or runs rough
- Difficulty starting the vehicle
- Check Engine Light illuminated
- Poor acceleration or sluggish performance
- Vehicle stalling or shutting off unexpectedly
How to Fix P0685 GMC
- Diagnose the issue using a scan tool to retrieve the specific trouble code and perform a visual inspection of the power relay control circuit.
- Inspect the wiring, connectors, and fuses related to the ECM power supply for any damage or corrosion.
- Test the ECM power relay to ensure it is functioning correctly or replace it if necessary.
- Clear the trouble code from the ECM's memory and test drive the vehicle to verify that the issue has been resolved.
- If the problem persists, further diagnosis may be required to identify any additional underlying issues contributing to the open circuit.
Cost to Fix P0685 GMC
The typical repair costs for addressing the P0685 code can vary depending on the specific cause of the issue and the labor rates in your area. In general, replacing a faulty ECM power relay or repairing damaged wiring may cost between $100 to $300, including parts and labor. However, if the ECM itself is found to be faulty, the cost can increase significantly, potentially ranging from $500 to $1000 or more. It's recommended to consult with a reputable auto repair shop for an accurate estimate based on your vehicle's make and model. Keep in mind that diagnostic time and labor rates can vary, so it's advisable to inquire about these factors before proceeding with the repair.
Tech Notes for P0685 GMC
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Information for Specific GMC Models
- P0685 2014 GMC Sierra — Engine Control Module Power Relay Control Circuit Open
- P0685 2015 GMC Sierra — Engine Control Module Power Relay Control Circuit Open
- P0685 2016 GMC Sierra — Engine Control Module Power Relay Control Circuit Open
- P0685 2017 GMC Sierra — Engine Control Module Power Relay Control Circuit Open
- P0685 2018 GMC Sierra — Engine Control Module Power Relay Control Circuit Open
Frequently Asked Questions about P0685 GMC Code
1. What are common symptoms of OBDII code P0685 in a GMC vehicle?
- Common symptoms include engine stalling, difficulty starting the engine, and a check engine light illuminated on the dashboard.
2. What does the OBDII code P0685 GMC indicate?
- The code P0685 indicates a malfunction in the Engine Control Module (ECM) power relay control circuit, specifically an open circuit.
3. What are potential causes of the P0685 code in a GMC vehicle?
- Possible causes include a faulty ECM power relay, damaged wiring or connectors in the relay control circuit, or a malfunctioning ECM.
4. How can I diagnose the cause of the P0685 code in my GMC vehicle?
- To diagnose the issue, you can perform a visual inspection of the relay and related wiring, test the relay for continuity, and use a multimeter to check for proper voltage in the circuit.
5. What are some repair tips for fixing the P0685 code in a GMC vehicle?
- Repair options may include replacing the ECM power relay, repairing or replacing damaged wiring or connectors, or replacing the ECM itself if deemed faulty.
6. Can driving with the P0685 code present cause further damage to the vehicle?
- Continuing to drive with the P0685 code present can potentially cause further damage to the engine control system and may lead to more severe issues over time.
7. Is it safe to clear the P0685 code and continue driving without addressing the underlying problem?
- Clearing the code without addressing the underlying issue is not recommended, as the problem will likely persist and could potentially worsen, leading to more significant repairs.
8. How much does it typically cost to repair the P0685 code in a GMC vehicle?
- The cost of repair can vary depending on the specific cause of the issue, but it may range from around $100 to $500 or more, including parts and labor.
9. Can I fix the P0685 code in my GMC vehicle myself, or should I seek professional help?
- While some DIY enthusiasts may be able to diagnose and repair the issue themselves, it is often recommended to seek professional help, especially if you are not experienced with automotive electrical systems.
10. How long does it usually take to resolve the P0685 code in a GMC vehicle?
- The repair time can vary depending on the extent of the issue and the availability of parts, but it typically takes a few hours to a full day to diagnose and fix the problem.
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