The P1685 trouble code is associated with the Smart Key Immobilizer Module (SKIM) and indicates an “Invalid SKIM Key.” This code is primarily found in Chrysler, Jeep, and Dodge vehicles equipped with a transponder key system. When the vehicle’s Powertrain Control Module (PCM) detects a mismatch between the key’s transponder ID and the stored IDs in the SKIM, it triggers this code. This can lead to starting issues, as the vehicle may not recognize the key, effectively immobilizing it.
Understanding this code is crucial for vehicle owners and DIY mechanics, as it can stem from various issues ranging from a faulty key to a malfunctioning SKIM module. This guide will delve into the meaning of the P1685 code, its common causes, symptoms, and detailed steps for diagnosis and resolution.
| P1685 Code Meaning | P1685 Code Common Causes |
|---|---|
| Invalid SKIM Key | Incorrect key used |
| Transponder chip malfunction | Faulty SKIM module |
| Key not programmed to vehicle | PCM issues |
| Attempted theft detected | Damaged ignition switch |
Symptoms of P1685 Code
The symptoms associated with the P1685 trouble code can vary, but common indicators include:
- Engine Cranks but Does Not Start: The vehicle may turn over but fails to start.
- Security Indicator Light: The security light on the dashboard may remain illuminated.
- Intermittent Starting Issues: The vehicle may start sometimes but fail at other times.
- Limp Mode Activation: In some cases, the vehicle may enter limp mode, limiting performance until the issue is resolved.
Technical Explanation
The P1685 code is generated when the SKIM detects that the transponder ID from the key does not match any of the IDs stored in its memory. This situation can arise due to several reasons:
- Incorrect Key: Using a key that is not programmed for that specific vehicle.
- Transponder Chip Issues: The chip within the key may be faulty or damaged.
- SKIM Malfunction: The module responsible for reading the transponder information could be defective.
- PCM Problems: If there are issues with the PCM itself, it may not correctly interpret signals from the SKIM.
Step-by-Step Diagnosis
To diagnose a P1685 trouble code effectively, follow these steps:
- Initial Scan: Use an OBD-II scanner to confirm that P1685 is present and check for any additional codes that might provide more context.
- Inspect Key: Examine the key for physical damage or wear. If possible, try using a spare key to see if it resolves the issue.
- Check Battery Voltage: Ensure that your vehicle’s battery is fully charged and in good condition, as low voltage can affect electronic systems.
- Examine SKIM Module: Inspect wiring and connections to the SKIM module for any signs of damage or corrosion.
- Test Ignition Switch: Verify that the ignition switch is functioning correctly and making proper contact when turned.
- Reprogram Key: If using a spare key works, consider reprogramming your primary key or replacing it if needed.
- Professional Diagnostics: If problems persist after these checks, consult a professional technician who can perform advanced diagnostics using manufacturer-specific tools.
Solution Methods
Resolving a P1685 trouble code typically involves one or more of the following methods:
Reprogramming or Replacing Keys
If you suspect that your key is faulty or not programmed correctly:
- Obtain a new key from your dealership or locksmith.
- Use an OBD-II scanner capable of programming keys to reprogram your existing keys if you have access to one.
Replacing or Repairing SKIM Module
If diagnostics indicate that the SKIM module is malfunctioning:
- Replace the SKIM module with a new one compatible with your vehicle model.
- Ensure proper programming of the new SKIM module to match your vehicle’s PCM.
PCM Reset
After addressing any key or SKIM issues:
- Disconnect the battery terminals.
- Press down on the brake pedal for about 30 seconds to discharge residual power.
- Reconnect battery terminals.
- Start your vehicle to see if the code clears itself after resolving underlying issues.
Professional Help
If DIY methods do not resolve the issue:
- Consult an ASE-certified technician who can perform in-depth diagnostics and repairs using specialized equipment.
Cost Estimates
The cost to resolve a P1685 trouble code can vary based on several factors:
- Key Replacement/Programming: $50 – $300 depending on whether you go through a dealership or locksmith.
- SKIM Module Replacement: $200 – $600 including parts and labor.
- Professional Diagnostics: $100 – $150 for a complete diagnostic check at a dealership or repair shop.
Warnings and Recommendations
- Always use keys that are specifically programmed for your vehicle model to avoid triggering immobilizer codes.
- If you experience repeated issues with starting or suspect theft attempts, consider enhancing your vehicle’s security system.
- Avoid attempting repairs beyond your skill level; improper handling of electronic components can lead to further complications.
Closing Paragraph
The P1685 trouble code signifies an important aspect of your vehicle’s security system related to its ability to recognize valid keys. By understanding its causes and following systematic diagnostic steps, you can effectively address this issue without unnecessary costs. Whether you’re replacing keys or seeking professional help, being informed will empower you as a vehicle owner or DIY mechanic to tackle this challenge confidently.
Frequently Asked Questions About P1685
- What does P1685 mean?
P1685 indicates an “Invalid SKIM Key,” meaning that the transponder ID from your key does not match what is stored in your vehicle’s security system. - Can I drive my car with a P1685 code?
No, typically you will be unable to start your car until this issue is resolved. - How do I clear a P1685 code?
You can clear it by addressing its cause (like replacing or reprogramming keys) and then performing a PCM reset. - Is it safe to replace my own SKIM module?
If you’re experienced with automotive electronics, you may attempt it; otherwise, seek professional assistance. - Why does my car go into limp mode with P1685?
Limp mode activates as a safety feature when critical systems are compromised, such as when an invalid key is detected. - Can weather affect my key’s performance?
Yes, extreme temperatures can affect battery life in transponder keys and potentially lead to starting issues. - Do I need special tools to diagnose P1685?
An OBD-II scanner is essential for diagnosing this code accurately. - How often should I check my keys?
Regularly inspect your keys for wear and tear; replace them if they show signs of damage.