The P0573 code is a diagnostic trouble code (DTC) that indicates a problem with the cruise control brake switch circuit. This code is typically triggered when the vehicle’s powertrain control module (PCM) detects a higher than normal voltage in the cruise control brake switch circuit. Understanding and resolving this issue is crucial for maintaining proper functionality of your vehicle’s cruise control system and ensuring safe operation on the road.
| P0573 Code Meaning | P0573 Code Common Causes |
|---|---|
| Cruise Control/Brake Switch A Circuit High | Faulty cruise control brake switch |
| High voltage detected in the brake switch circuit | Damaged or corroded wiring in the brake switch circuit |
| Malfunction in the cruise control system | Blown fuse in the cruise control system |
| Brake pedal position sensor issue | Misadjusted or stuck brake pedal |
| PCM detects abnormal resistance in the circuit | Faulty PCM (rare) |
Symptoms of P0573 Code
When your vehicle’s onboard computer detects the P0573 code, you may experience several symptoms that can affect your driving experience. It’s essential to be aware of these signs to address the issue promptly:
- Inoperative Cruise Control: The most common and noticeable symptom is that your cruise control system may not function at all. You might find that you’re unable to engage or set the cruise control, even if the indicator light on your dashboard illuminates.
- Erratic Cruise Control Behavior: In some cases, the cruise control may work intermittently or behave erratically. It might engage and disengage unexpectedly, or fail to maintain a consistent speed.
- Check Engine Light: The P0573 code will often trigger the check engine light on your dashboard. This warning light serves as an alert that your vehicle’s onboard diagnostic system has detected an issue.
- Brake Lights Malfunction: Since the brake switch is involved, you may notice issues with your brake lights. They might remain on constantly or fail to illuminate when you press the brake pedal.
- Difficulty Shifting Out of Park (in some vehicles): In certain vehicle models, the brake switch is also used as an input for the shift interlock system. A malfunctioning switch might make it difficult to shift out of park.
- Reduced Fuel Efficiency: If the cruise control is not working correctly, you may notice a slight decrease in fuel efficiency, especially during highway driving where cruise control is commonly used.
- Stalling or Hesitation: In rare cases, a severe malfunction related to this code might cause the engine to stall or hesitate, particularly when coming to a stop.
It’s important to note that the severity and combination of symptoms can vary depending on the specific make and model of your vehicle, as well as the extent of the underlying issue causing the P0573 code.
Technical Explanation of P0573 Code
To fully understand the P0573 code, it’s crucial to delve into the technical aspects of how the cruise control and brake switch systems interact within your vehicle:
The cruise control brake switch, also known as the cruise control release switch, is a critical component in the safe operation of your vehicle’s cruise control system. Its primary function is to disengage the cruise control when the brake pedal is pressed. This switch is typically integrated with or located near the brake pedal assembly.
When functioning correctly, the brake switch sends a low voltage signal to the Powertrain Control Module (PCM) when the brake pedal is not pressed. When you apply the brakes, the switch changes state, sending a high voltage signal to the PCM. This signal tells the PCM to immediately disengage the cruise control, ensuring that the vehicle slows down as expected when you brake.
The P0573 code specifically indicates that the PCM has detected a high voltage in this circuit when it shouldn’t be present. In normal operation, the voltage in this circuit should be low (typically less than 1.5 volts) when the brake pedal is not pressed. When the code is set, it means the PCM is seeing a voltage higher than expected (usually above 4.5 volts) even when the brake pedal is not being pressed.
This high voltage could be caused by several factors:
- A short circuit to power in the wiring between the brake switch and the PCM
- A faulty brake switch that’s stuck in the “on” position
- A problem with the PCM itself (though this is less common)
The cruise control system relies on accurate input from this switch to function safely. If the PCM detects an issue with this circuit, it will typically disable the cruise control system as a safety precaution, which explains why the most common symptom of this code is an inoperative cruise control.
Understanding this technical background is crucial for diagnosing and resolving the P0573 code effectively.
Step-by-Step Diagnosis of P0573 Code
Diagnosing the P0573 code requires a systematic approach. Here’s a detailed step-by-step guide to help you or your mechanic pinpoint the issue:
- Verify the Code:
- Connect an OBD-II scanner to your vehicle’s diagnostic port.
- Turn the ignition to the “On” position without starting the engine.
- Retrieve the diagnostic trouble codes (DTCs) from the vehicle’s computer.
- Confirm that P0573 is present and note any additional codes.
- Check Technical Service Bulletins (TSBs):
- Research if there are any TSBs related to the P0573 code for your specific vehicle make, model, and year.
- TSBs can provide valuable information about known issues and manufacturer-recommended fixes.
- Inspect the Brake Light Switch:
- Locate the brake light switch near the brake pedal assembly.
- Check if the switch is properly adjusted and making contact with the brake pedal arm.
- Inspect the switch for any visible damage or corrosion.
- Test the Brake Light Switch:
- Disconnect the electrical connector from the brake light switch.
- Use a multimeter to check the switch’s continuity.
- With the brake pedal released, there should be no continuity.
- When the brake pedal is pressed, there should be continuity.
- If the results are inconsistent, the switch may be faulty and need replacement.
- Inspect Wiring and Connectors:
- Examine the wiring harness connected to the brake light switch.
- Look for any signs of damage, fraying, or exposed wires.
- Check the connectors for corrosion, bent pins, or loose connections.
- Ensure the wiring is properly routed and not pinched or stretched.
- Check Fuses:
- Locate the fuse box and identify the fuse associated with the cruise control system.
- Inspect the fuse visually or use a multimeter to check for continuity.
- Replace the fuse if it’s blown, but be aware that a blown fuse often indicates a larger electrical issue.
- Perform a Voltage Test:
- With the ignition on, use a multimeter to measure the voltage at the brake switch connector.
- Check the voltage with the brake pedal pressed and released.
- Compare the readings to the manufacturer’s specifications in the service manual.
- Check PCM Inputs and Outputs:
- Using a professional-grade scan tool, monitor the PCM’s input and output signals related to the brake switch and cruise control.
- Compare these readings to the expected values in your vehicle’s service manual.
- Road Test:
- Clear the diagnostic codes and perform a road test.
- Attempt to engage the cruise control and observe its behavior.
- Pay attention to any other unusual symptoms.
- Recheck for Codes:
- After the road test, scan for codes again to see if P0573 returns.
- If the code reappears, you may need to perform more in-depth diagnostics or seek professional assistance.
Remember, while these steps can help identify many common causes of the P0573 code, some issues may require specialized equipment or expertise to diagnose accurately. If you’re unsure at any point, it’s best to consult with a professional mechanic.
Solution Methods for P0573 Code
Once you’ve diagnosed the root cause of the P0573 code, you can proceed with the appropriate solution. Here are detailed methods to address common issues:
- Replacing the Brake Light Switch:
- Disconnect the negative battery terminal to prevent electrical shorts.
- Locate the brake light switch near the brake pedal assembly.
- Unplug the electrical connector from the switch.
- Remove any mounting hardware securing the switch.
- Install the new brake light switch, ensuring it’s properly adjusted to make contact with the brake pedal arm.
- Reconnect the electrical connector and battery terminal.
- Test the brake lights and cruise control functionality.
- Repairing Wiring Issues:
- Identify the damaged section of wiring.
- Cut out the damaged portion, leaving enough wire on both ends to work with.
- Strip the ends of the wires and use appropriate gauge wire to bridge the gap.
- Use heat-shrink butt connectors or solder the connections, then insulate with heat-shrink tubing.
- Secure the repaired wiring with electrical tape or wire loom to prevent future damage.
- Cleaning Corroded Connectors:
- Disconnect the connector carefully.
- Use an electrical contact cleaner spray to remove corrosion.
- Gently scrub stubborn corrosion with a small wire brush.
- Apply dielectric grease to the clean connector to prevent future corrosion.
- Reconnect and ensure a tight, secure fit.
- Adjusting the Brake Pedal:
- Locate the brake pedal adjustment mechanism, typically a threaded rod or bolt.
- Loosen the locknut if present.
- Adjust the rod or bolt to achieve the correct brake pedal height and free play according to your vehicle’s specifications.
- Tighten the locknut to secure the adjustment.
- Verify that the brake switch engages and disengages properly with pedal movement.
- Replacing a Blown Fuse:
- Locate the correct fuse in the fuse box (refer to your vehicle’s manual).
- Remove the old fuse using fuse pullers or needle-nose pliers.
- Insert a new fuse of the same amperage rating.
- Test the cruise control system to ensure it’s working properly.
- PCM Reprogramming or Replacement:
Note: This should only be performed by a qualified professional.
- Connect a professional-grade scan tool to the vehicle’s OBD-II port.
- Follow the manufacturer’s procedure for updating the PCM software.
- If reprogramming doesn’t resolve the issue, PCM replacement may be necessary.
- After replacement, the new PCM will need to be programmed with your vehicle’s specific parameters.
After performing any of these solutions, clear the diagnostic trouble codes and perform a road test to ensure the P0573 code doesn’t return. If the problem persists, further diagnosis may be necessary.
Cost Estimates for Fixing P0573 Code
The cost of resolving the P0573 code can vary significantly depending on the root cause of the problem and whether you choose to do the work yourself or hire a professional. Here’s a breakdown of potential costs:
- DIY Brake Light Switch Replacement:
- Parts: $20 – $50
- Tools: $10 – $30 (if you don’t already have them)
- Total DIY Cost: $30 – $80
- Professional Brake Light Switch Replacement:
- Parts: $20 – $50
- Labor: $50 – $100
- Total Professional Cost: $70 – $150
- Wiring Repair:
- DIY Cost: $10 – $30 for materials
- Professional Cost: $100 – $300 (depending on the extent of the damage)
- Fuse Replacement:
- DIY Cost: $5 – $10
- Professional Cost: $50 – $100 (including diagnostic fee)
- PCM Reprogramming:
- Professional Cost: $100 – $200
- PCM Replacement:
- Parts: $500 – $1000
- Labor: $200 – $500
- Total Professional Cost: $700 – $1500
- Diagnostic Fee:
- If you’re unsure of the cause, most shops charge a diagnostic fee of $50 – $150
Remember, these are estimated costs and can vary based on your specific vehicle make and model, as well as your geographic location. Always get a detailed quote from a reputable mechanic before proceeding with repairs.
Warnings and Recommendations
When dealing with the P0573 code, keep the following warnings and recommendations in mind:
Safety First: Always disconnect the negative battery terminal before working on electrical components to prevent short circuits or electrical shocks.
Use Proper Tools: Ensure you have the correct tools for the job. Using improper tools can damage components or lead to inaccurate diagnoses.
Refer to the Service Manual: Always consult your vehicle’s service manual for specific procedures and specifications. Different makes and models may have unique requirements.
Be Cautious with Electrical Components: When working with wiring and connectors, be gentle to avoid causing additional damage.
Don’t Ignore the Problem: While a non-functioning cruise control might seem like a minor inconvenience, it could be indicative of a more serious electrical issue that could affect other vehicle systems.
Consider Professional Help: If you’re unsure about any step in the diagnostic or repair process, don’t hesitate to seek professional assistance. Incorrect repairs can lead to more expensive problems down the line.
Quality Parts: When replacing components, use high-quality, OEM or equivalent parts to ensure proper fit and function.
Clear Codes After Repair: Always clear the diagnostic trouble codes after completing repairs and perform a road test to ensure the problem is resolved.
Address Related Issues: If you notice any other symptoms or related codes, address them as well. Sometimes, multiple issues can be interconnected.
Regular Maintenance: Keep up with your vehicle’s regular maintenance schedule to prevent future issues and catch potential problems early.
By following these guidelines and approaching the P0573 code systematically, you can effectively diagnose and resolve the issue, ensuring your vehicle’s cruise control system functions properly and safely.
Conclusion
The P0573 code, while primarily affecting the cruise control system, can be indicative of broader electrical issues in your vehicle. By understanding the meaning of this code, recognizing its symptoms, and following