P0585 Code: Complete DIY Repair Guide

The P0585 trouble code is a diagnostic trouble code (DTC) that indicates a problem with the cruise control system in a vehicle. Specifically, it refers to a discrepancy between the voltage inputs from the cruise control multi-function switch. This code is applicable to a wide range of vehicles and signifies that the Powertrain Control Module (PCM) has detected an inconsistency in the signals it receives from the cruise control system, which can lead to issues with maintaining speed while driving.

Symptoms of P0585 Code

When a vehicle registers a P0585 trouble code, several symptoms may be observed:

• Inoperative Cruise Control System: The most noticeable symptom is that the cruise control will not function as intended.
• Erratic Speedometer/Odometer Operation: Fluctuations or inaccuracies in speed readings may occur.
• Flashing or Unresponsive Cruise Control Indicator Lamp: The indicator light for cruise control may blink or fail to illuminate.
• Other Stored Codes: Additional trouble codes may be present, indicating related issues.

Technical Explanation of P0585 Code

The P0585 code specifically deals with the cruise control system, which relies on inputs from various switches and sensors to maintain vehicle speed. The multi-function switch, which often controls multiple vehicle functions, sends voltage signals to the PCM. If these signals do not correlate as expected—meaning that input A does not match input B—the PCM triggers the P0585 code.

The cruise control system typically becomes active once the vehicle exceeds 35 mph. It works by adjusting throttle position based on input commands from the driver via the multi-function switch. If there is a malfunction in any part of this system, such as a faulty switch or wiring issues, it can lead to an inability to maintain speed.

Step-by-Step Diagnosis of P0585 Code

Diagnosing a P0585 trouble code involves several steps:

1. Initial Inspection: Begin with a visual inspection of all related wiring and connectors for signs of damage or corrosion.
2. Scan for Codes: Use an OBD-II scanner to retrieve all stored codes and freeze frame data. Document this information for reference.
3. Clear Codes and Test Drive: Clear the codes and take the vehicle for a test drive to see if the P0585 code reappears.
4. Voltage Testing: Using a digital volt/ohmmeter (DVOM), check the voltage at the multi-function switch. Compare this with specifications provided in your vehicle’s service manual.
5. Inspect Switch Functionality: Test the multi-function switch for proper operation. If it fails to send correct signals, replacement may be necessary.
6. Check Cruise Control Module: If all else appears functional, inspect or test the cruise control module and PCM for faults.
7. Refer to Technical Service Bulletins (TSBs): Look for any TSBs related to your vehicle make and model that might provide additional troubleshooting guidance.

Solution Methods for P0585 Code

Resolving a P0585 code can involve several methods depending on the underlying cause:

• Replace Defective Multi-Function Switch: If testing indicates that the multi-function switch is faulty, replacing it will often resolve the issue.
• Repair Wiring Issues: If there are open or shorted circuits detected, repairing or replacing damaged wiring will be necessary.
• Replace Cruise Control Servo Motor: A malfunctioning servo motor can also trigger this code; testing its functionality and replacing it if needed is crucial.
• Reprogram PCM: In cases where programming errors are suspected, reprogramming or updating the PCM software may be required.

Cost Estimates for Repairs

The cost of repairs associated with a P0585 trouble code can vary widely based on several factors:

• Multi-Function Switch Replacement: $100 – $300 (parts and labor)
• Wiring Repairs: $50 – $150 (depending on extent of damage)
• Cruise Control Servo Motor Replacement: $150 – $400 (parts and labor)
• PCM Reprogramming: $75 – $150 (if performed by a dealership or specialized technician)

Keep in mind that these estimates can vary based on location and specific vehicle make/model.

Warnings and Recommendations

• Professional Help Recommended: If you are not comfortable diagnosing electrical issues, it is advisable to seek professional assistance to avoid further complications.
• Safety First: Always ensure that your vehicle is safe to drive until repairs are made; an inoperative cruise control system does not generally affect basic driving but could pose risks during long trips.
• Regular Maintenance Checks: Regularly inspect your vehicle’s electrical systems as part of routine maintenance to catch potential issues early.

Closing Paragraph

The P0585 trouble code indicates an issue within your vehicle’s cruise control system, primarily involving input discrepancies from the multi-function switch. Understanding this code’s implications allows vehicle owners and DIY mechanics to diagnose and address problems effectively. By following systematic diagnostic steps, utilizing proper tools, and knowing when to seek professional help, you can ensure your vehicle remains safe and functional on the road.

Frequently Asked Questions About P0585

• What does the P0585 code mean?
  The P0585 code indicates a correlation issue between inputs A and B from the cruise control multi-function switch.
• Can I drive my car with a P0585 code?
  While it is generally safe to drive without functional cruise control, it’s important to address this issue promptly.
• How serious is a P0585 code?
  This code primarily affects cruise control functionality; however, it should be diagnosed as soon as possible.
• What tools do I need to diagnose a P0585 code?
  A digital volt/ohmmeter (DVOM) and an OBD-II scanner are essential tools for diagnosing this trouble code.
• Is there a way to reset the P0585 code?
  You can reset this code by clearing it with an OBD-II scanner after performing any necessary repairs.
• What vehicles commonly experience P0585 codes?
  This trouble code can occur in many vehicles equipped with electronic cruise control systems.
• What should I check first when diagnosing a P0585?
  Start with inspecting wiring and connectors associated with the cruise control system for any visible damage.
• Can other codes accompany P0585?
  Yes, it’s common for other related codes to appear alongside P0585 due to interconnected systems.