The P0585 trouble code is a diagnostic trouble code (DTC) that indicates an issue with the cruise control system in a vehicle. Specifically, it refers to a discrepancy between the voltage inputs of the cruise control multi-function switch, which is responsible for controlling various functions including speed control. When this code is triggered, it suggests that the powertrain control module (PCM) has detected an inconsistency in the signals from the cruise control switches, which can lead to malfunctioning or inoperative cruise control.
This article aims to provide vehicle owners and DIY mechanics with a comprehensive guide on understanding, diagnosing, and resolving the P0585 trouble code.
| P0585 Code Meaning | P0585 Code Common Causes |
|---|---|
| Cruise Control Multi-Function Input A/B Correlation Error | Defective multi-function switch |
| Speed Control Switch 1/2 Correlation Error | Bad cruise control servo motor |
| Inoperative Cruise Control System | Open or shorted circuits in the cruise control system |
| Erratic Speedometer/Odometer Operation | Faulty cruise control module or PCM programming error |
| Malfunction Indicator Lamp (MIL) On | Poor electrical connections or damaged wiring |
Symptoms of P0585 Trouble Code
When dealing with a P0585 code, vehicle owners may notice several symptoms indicating that the cruise control system is not functioning properly:
- Inoperative Cruise Control System: The most obvious symptom is that the cruise control will not engage or maintain speed.
- Erratic Speedometer/Odometer Operation: Fluctuations in speed readings can occur when there are issues with the cruise control system.
- Flashing or Unresponsive Cruise Control Indicator Lamp: The dashboard indicator for cruise control may flash or fail to respond when activated.
- Other Stored Codes: Additional trouble codes may be present, indicating related issues within the vehicle’s electrical systems.
Understanding P0585 Code
Technical Explanation
The P0585 code arises when the PCM detects a mismatch between the voltage signals from two separate inputs of the cruise control multi-function switch. This switch controls various functions such as activating cruise control, setting speed, and adjusting speed. The PCM relies on these inputs to manage the cruise control system effectively. If one input does not correlate with another, it raises a flag and stores the P0585 code.
Step-by-Step Diagnosis
Diagnosing a P0585 code involves several steps:
- Visual Inspection: Check for any obvious signs of damage to wiring and connectors associated with the cruise control system.
- Scan for Codes: Use an OBD-II scanner to retrieve all stored codes and freeze frame data. This information can provide insights into other potential issues.
- Check Voltage at Multi-Function Switch: Using a digital volt/ohmmeter (DVOM), measure voltage at the multi-function switch to ensure it is within specifications.
- Inspect Cruise Control Switches: Examine both switches for physical damage or wear that could impede functionality.
- Test Wiring and Connections: Look for corrosion, loose connections, or damaged wiring that could affect signal transmission.
- Check Cruise Control Module: Inspect this component for faults or damages that could be contributing to the problem.
- Reset and Retest: After addressing any issues found, clear the codes and perform a test drive to see if the problem persists.
Solution Methods
Resolving a P0585 code often involves one or more of the following methods:
- Replace Defective Multi-Function Switch: If testing reveals that the switch is faulty, replacement is necessary to restore proper function.
- Repair Wiring Issues: Address any damaged wiring or poor connections found during inspection.
- Service Cruise Control Module: If the module is determined to be faulty, it may need reprogramming or replacement by a professional mechanic.
- Check for Software Updates: Sometimes, updating the vehicle’s software can resolve underlying programming issues affecting performance.
Cost Estimates for Repair
The cost of diagnosing and repairing a P0585 code can vary widely based on several factors:
- Diagnostic Fees: Expect to pay between $100 to $150 for professional diagnostics if you choose not to perform them yourself.
- Parts Replacement:
- Multi-function switch replacement costs can range from $50 to $200 depending on vehicle make and model.
- Wiring repairs may cost between $50 to $150 based on labor rates and parts needed.
- A new cruise control module might range from $150 to $500 depending on complexity and vehicle type.
Overall, total repair costs could range from $200 to over $800 depending on parts needed and labor costs involved.
Warnings and Recommendations
- Professional Help Needed: If you are not comfortable diagnosing electrical systems or if multiple codes are present, it is advisable to seek professional assistance from a certified mechanic.
- Safety First: Always ensure that your vehicle is safely parked and turned off before attempting any inspections or repairs on electrical components.
- Avoid Ignoring Codes: While a P0585 code may not seem critical at first glance, ignoring it can lead to further complications in your vehicle’s performance over time.
Frequently Asked Questions About P0585
- What causes a P0585 code?
The P0585 code is typically caused by issues with the multi-function switch, wiring problems, or faults within the cruise control module. - Can I drive my car with a P0585 code?
While it’s generally safe to drive your vehicle with this code, you may experience unreliable cruise control functionality. - How do I clear a P0585 code?
You can clear this code using an OBD-II scanner after addressing any underlying issues. - Is it necessary to replace both switches if one is faulty?
It’s often recommended to replace both switches if one shows signs of failure due to their interconnected functionality. - What tools do I need to diagnose a P0585?
A diagnostic scanner and digital volt/ohmmeter (DVOM) are essential tools for diagnosing this trouble code. - How long does it take to fix a P0585 issue?
The time required can vary; simple fixes may take an hour while more complex repairs could take several hours. - Can low battery voltage trigger a P0585 code?
Yes, low battery voltage can affect electronic components and potentially trigger this trouble code. - What should I do if my cruise control works intermittently?
If your cruise control works intermittently, inspect switches and wiring thoroughly as intermittent faults are often linked to poor connections.
In conclusion, understanding and addressing the P0585 trouble code involves recognizing its symptoms, conducting thorough diagnostics, and implementing appropriate solutions. By following these guidelines, vehicle owners and DIY mechanics can effectively manage this issue and ensure their cruise control systems function reliably.