The P1685 trouble code is a diagnostic trouble code (DTC) that indicates an issue with the vehicle’s security system, specifically related to the Smart Key Immobilizer Module (SKIM). This code is set when the ignition system detects an invalid key, which can prevent the engine from starting. Understanding the implications of this code is crucial for vehicle owners and DIY mechanics, as it often signals a need for immediate attention to avoid further complications.
| P1685 Code Meaning | P1685 Code Common Causes |
|---|---|
| Invalid SKIM Key | Incorrect key used in ignition |
| Key not programmed correctly | Faulty transponder chip in the key |
| Communication error with SKIM module | Malfunctioning SKIM module |
| PCM (Powertrain Control Module) issues | Incorrect VIN in PCM programming |
| Battery issues affecting SKIM operation | Recent battery disconnection or failure |
Symptoms of P1685 Code
When the P1685 code is triggered, several symptoms may manifest, indicating a problem with the vehicle’s ability to start. Common symptoms include:
- Engine Crank No Start: The engine may crank but fail to start.
- SKIM Light On: The security light on the dashboard may illuminate, indicating a problem with the key or immobilizer system.
- Intermittent Starting Issues: The vehicle may start intermittently, leading to frustration and uncertainty.
- Loss of Power: In some cases, there may be a noticeable loss of power or performance when driving.
Technical Explanation of P1685 Code
The P1685 code is primarily associated with the Sentry Key Immobilizer Module (SKIM), which is designed to enhance vehicle security by preventing unauthorized access. When a key is inserted into the ignition, the SKIM reads the transponder chip embedded in the key. If the transponder ID does not match any stored in the SKIM’s memory, it triggers the P1685 code.
Step-by-Step Diagnosis
- Check for Additional Codes: Use an OBD-II scanner to check for other related trouble codes that may provide more context.
- Inspect Keys: Verify that you are using the correct key and check for physical damage or wear on the key.
- Test Transponder Functionality: Ensure that the transponder chip in the key is functioning correctly. This can be done using specialized equipment at a dealership or automotive locksmith.
- Examine SKIM Module Connections: Inspect wiring and connections to the SKIM module for any signs of damage or corrosion.
- Verify PCM Programming: Ensure that the PCM has been programmed with the correct VIN and that there are no discrepancies.
- Check Battery Condition: Inspect the battery and charging system to ensure they are functioning properly, as low voltage can affect SKIM operation.
Solution Methods for P1685 Code
1. Key Replacement and Reprogramming
If a faulty key is suspected, replacing it with a new one and reprogramming it to match the vehicle’s SKIM may resolve the issue.
Cost Estimate
- Key replacement: $50 – $200
- Reprogramming service: $50 – $150
Warnings and Recommendations
- Always use keys that are specifically designed for your vehicle model.
- If unsure about programming, seek professional assistance from a dealer or locksmith.
2. SKIM Module Replacement
If diagnostics point to a malfunctioning SKIM module, replacing it may be necessary.
Cost Estimate
- SKIM module replacement: $200 – $600
- Labor costs: $100 – $200
Warnings and Recommendations
- Ensure proper programming of the new module to avoid future issues.
- Consult with a professional technician for installation.
3. PCM Reset
In some cases, resetting the PCM can clear temporary codes and allow normal operation.
Step-by-Step Instructions
- Disconnect the negative battery terminal.
- Press and hold the brake pedal for 30 seconds.
- Reconnect the battery terminal.
- Attempt to start the vehicle.
Cost Estimate
- DIY reset: Free
- Professional reset: $50 – $100
Warnings and Recommendations
- A reset should be performed only after ensuring all underlying issues have been addressed.
4. Battery Inspection and Replacement
Since battery issues can trigger false codes, ensuring your battery is in good condition is essential.
Cost Estimate
- Battery replacement: $100 – $300
Warnings and Recommendations
- Regularly check battery health to prevent future issues.
- Use a multimeter to test voltage; it should read around 12.6 volts when fully charged.
Closing Paragraph
The P1685 trouble code indicates an issue with your vehicle’s security system related to an invalid key detected by the Smart Key Immobilizer Module (SKIM). By understanding its causes, symptoms, and solutions, vehicle owners can take informed steps toward resolving this issue effectively. Whether it’s replacing a faulty key, reprogramming modules, or addressing battery concerns, timely action can prevent further complications and ensure your vehicle operates smoothly.
Frequently Asked Questions About P1685
- What does P1685 mean?
The P1685 code indicates an invalid key detected by your vehicle’s Smart Key Immobilizer Module (SKIM), preventing engine start. - Can I drive my car with a P1685 code?
No, driving with this code could lead to starting issues; it’s best to address it immediately. - How do I clear a P1685 code?
You can clear it by resetting your PCM or using an OBD-II scanner after resolving any underlying issues. - Is it safe to replace my own key?
Yes, but ensure it’s properly programmed; otherwise, you might still face starting issues. - What if my car still won’t start after replacing the key?
If replacing the key doesn’t work, further diagnostics on your SKIM or PCM may be required. - How much does it cost to fix a P1685 code?
The total cost varies widely depending on whether you need a new key, SKIM module replacement, or other repairs; estimates range from $50 to over $600. - Can I fix this issue myself?
Many DIY mechanics can handle basic checks like battery inspection or key replacement; however, complex tasks may require professional help. - What tools do I need for diagnosis?
An OBD-II scanner is essential for diagnosing trouble codes accurately.