P0573
UniversalCruise Control/Brake Switch A Circuit High
Medium SeverityThe P0573 code indicates that the vehicle's engine control unit (ECU) has detected a high voltage input from the brake switch 'A' circuit, which is often used by the cruise control system. This typically means the switch is stuck in a closed (on) position or there is an electrical fault, potentially affecting cruise control operation and brake light function.
⚠️ Before You Begin (Safety First)
Always ensure the vehicle is safely parked with the parking brake engaged before attempting any repairs. If working with electrical components, disconnect the battery's negative terminal to prevent accidental short circuits or electrical shock. Be cautious around hot engine components.
Common Symptoms
- Cruise control does not engage or disengage
- Brake lights remain on constantly
- Brake lights do not illuminate
- Check Engine Light (CEL) illuminated
- Transmission shifting issues (in some vehicles)
Common Causes
- Faulty brake light switch
- Corroded or damaged wiring to the brake switch
- Poor electrical connection at the brake switch
- Short circuit to voltage in the brake switch circuit
- Faulty cruise control module (less common)
- Faulty Engine Control Unit (ECU) (rare)
Frequently reported on: General/Universal
Diagnostic Steps
- Locate the brake light switch, typically mounted near the brake pedal arm under the dashboard.
- Disconnect the electrical connector from the switch.
- Remove the old brake light switch, which often involves twisting or unclipping it from its mounting.
- Install the new brake light switch, ensuring it is properly seated and adjusted according to manufacturer specifications.
- Reconnect the electrical connector.
- Reconnect the vehicle's battery (if disconnected).
- Clear the P0573 code using an OBD-II scanner and test the brake lights and cruise control functionality.
👨🔧 When to Call a Professional
If after replacing the brake light switch, the code persists or other electrical issues arise, it's advisable to consult a professional technician. This could indicate a more complex wiring harness issue or a fault within the vehicle's ECU requiring advanced diagnostics.
Commonly Asked Questions
Can I drive with a P0573 code?
While the car may still be drivable, it's not recommended for extended periods. A faulty brake switch can cause issues with brake lights, which is a safety hazard, and can also affect cruise control operation.
Is the brake light switch expensive to replace?
No, the brake light switch itself is typically an inexpensive part, often costing between $15 and $50. The replacement process is usually straightforward for DIY mechanics.
Could a P0573 code cause my battery to drain?
Yes, if the faulty brake switch causes the brake lights to remain on constantly, it will drain your vehicle's battery over time, especially if left overnight.
How do I know if the new brake switch is correctly adjusted?
After installation, ensure your brake lights turn on when the pedal is pressed and turn off completely when released. Also, test your cruise control to ensure it engages and disengages correctly.
Does this code affect ABS or traction control?
In some modern vehicles, the brake switch signal is used by the ABS and traction control systems. A fault in this circuit could potentially impact the proper functioning of these safety systems.