The P1685 trouble code is a diagnostic trouble code (DTC) that indicates an issue with the Smart Key Immobilizer Module (SKIM) in certain vehicles, primarily those manufactured by Chrysler, Dodge, and Jeep. This code signifies that the vehicle has detected an invalid key message, meaning the transponder ID read by the SKIM does not match any of the stored IDs in its memory. This can prevent the vehicle from starting, leading to frustration for vehicle owners and DIY mechanics alike.
Understanding this code is crucial for diagnosing and resolving issues related to vehicle security systems, especially for those who may have experienced starting problems or intermittent engine shutdowns.
| P1685 Code Meaning | P1685 Code Common Causes |
|---|---|
| Invalid SKIM Key | Incorrect key used or key not programmed |
| Key not recognized by the SKIM | Defective SKIM module |
| Transponder chip failure | Faulty ignition switch or wiring issues |
| PCM not programmed correctly | Battery disconnection or low battery voltage |
Symptoms of P1685 Code
When dealing with a P1685 trouble code, vehicle owners may notice several symptoms that can indicate an issue with their vehicle’s ignition or security system. Common symptoms include:
- Engine Cranks but Does Not Start: The most noticeable symptom is that the engine will crank but will not turn over.
- Security Light Illumination: The security light on the dashboard may remain lit or flash, indicating a problem with the key recognition system.
- Intermittent Starting Issues: The vehicle may start intermittently, which can be frustrating and lead to uncertainty about reliability.
- Loss of Power: In some cases, drivers may experience a loss of power while driving, which could indicate broader electrical issues.
Technical Explanation of P1685 Code
The P1685 code is associated with the Smart Key Immobilizer Module (SKIM), which is part of the vehicle’s anti-theft system. The SKIM uses a transponder chip embedded in the ignition key to communicate with the Engine Control Module (ECM). When a key is inserted into the ignition and turned, the SKIM reads the transponder chip’s ID. If this ID does not match any ID stored within the SKIM’s memory, it triggers the P1685 code.
The SKIM module plays a critical role in ensuring that only authorized keys can start the vehicle. If any discrepancies arise—such as using an unprogrammed key or if there are issues with the SKIM itself—this code will be set.
Step-by-Step Diagnosis of P1685 Code
Diagnosing a P1685 trouble code involves several steps to identify and resolve the underlying issue. Follow this guide for a systematic approach:
- Scan for Codes: Use an OBD-II scanner to confirm that P1685 is present and check for any additional codes that might provide more context.
- Inspect Key and Ignition System:
- Check if you are using the correct key that has been programmed for your vehicle.
- Inspect the key for physical damage or wear.
- Ensure there are no other keys on the keyring that could interfere with transponder communication.
- Check Battery Condition:
- Verify that your vehicle’s battery is fully charged and connections are secure.
- A weak battery can cause communication issues between components.
- Examine SKIM Module:
- Inspect wiring and connectors leading to the SKIM module for damage or corrosion.
- If possible, test the SKIM module using specialized diagnostic tools.
- Test PCM Programming:
- Ensure that your PCM is correctly programmed with your vehicle’s VIN and compatible with your SKIM module.
- Reprogramming may be necessary if there are discrepancies.
- Check Ignition Switch:
- Test the ignition switch for proper operation as it can affect communication between components.
Solution Methods for P1685 Code
Once you have diagnosed the issue causing the P1685 code, you can proceed with appropriate solutions:
- Reprogram Key: If you find that your key is unprogrammed or has lost its programming, take it to a dealership or qualified locksmith to have it reprogrammed.
- Replace Faulty Components:
- If testing reveals a defective SKIM module or PCM, replacement may be necessary.
- Ensure any new components are programmed correctly to match your vehicle’s specifications.
- Repair Wiring Issues: Address any damaged wiring or poor connections found during inspections as these can lead to intermittent issues.
- Battery Maintenance: Ensure your battery is in good condition; replace it if necessary to avoid communication failures due to low voltage.
Cost Estimates for Repairs
The cost of repairs related to a P1685 code can vary widely depending on several factors including labor rates in your area and whether parts need replacement. Here are some rough estimates:
- Key Reprogramming: $50 to $150 at a dealership or locksmith.
- SKIM Module Replacement: $200 to $600 depending on parts and labor.
- PCM Reprogramming/Reflashing: $100 to $300 at a dealership.
- Wiring Repairs: $100 to $500 based on complexity and labor involved.
Warnings and Recommendations
- Always ensure you have a properly programmed key before attempting repairs related to this code. Using an incorrect key can lead to further complications.
- If you are uncomfortable performing these diagnostics or repairs yourself, seek assistance from a qualified mechanic or dealership technician.
- Be cautious when working with electrical components; disconnecting batteries or modules improperly can cause additional issues.
Closing Paragraph
The P1685 trouble code can be daunting for many vehicle owners and DIY mechanics, but understanding its implications and following systematic diagnostic steps can lead to successful resolution. By addressing potential causes such as faulty keys, defective modules, or wiring issues, you can restore functionality to your vehicle’s ignition system effectively. Always remember that when in doubt, consulting with professional mechanics ensures safety and accuracy in repairs.
Frequently Asked Questions About P1685
- What does P1685 mean?
The P1685 code indicates an “Invalid SKIM Key” message received by the Engine Control Module (ECM), meaning that the transponder ID from the key does not match stored IDs in the Smart Key Immobilizer Module (SKIM). - How do I fix a P1685 code?
Fixing a P1685 code typically involves reprogramming or replacing keys, checking battery conditions, inspecting wiring connections, and possibly replacing faulty modules. - Can I drive my car with a P1685 code?
No, driving with this code may result in starting issues as it prevents engine ignition until resolved. - Is it safe to clear codes without fixing them?
While you can clear codes temporarily, it is not advisable as underlying issues will persist and could lead to further complications. - What tools do I need to diagnose a P1685?
An OBD-II scanner is essential for reading codes; additional tools may include multimeters for electrical tests. - How much does it cost to fix a P1685?
The cost varies widely but generally ranges from $50 for key reprogramming up to $600 for module replacements. - Can I program my own keys?
Some vehicles allow DIY programming; however, many require specialized equipment available only at dealerships. - When should I seek professional help?
If you are unsure about diagnosing or repairing electrical components, it’s best to consult a professional mechanic.