P0571
UniversalCruise Control/Brake Switch A Circuit Malfunction
Medium SeverityThe P0571 code indicates a malfunction in the brake switch A circuit. This circuit is crucial for signaling when the brake pedal is pressed, affecting systems like cruise control disengagement and brake lights. A fault can lead to cruise control not disengaging or brake lights not working correctly.
⚠️ Before You Begin (Safety First)
Always ensure the vehicle is safely parked with the parking brake engaged before performing any inspections or repairs. Disconnect the negative battery terminal before working on electrical components to prevent accidental shorts or injury. Exercise extreme caution when testing electrical circuits, especially those related to braking systems.
Common Symptoms
- Brake lights not working or staying on
- Cruise control not engaging or not disengaging when the brake is pressed
- Intermittent or erratic cruise control operation
- Check Engine Light illuminated
- In some vehicles, difficulty shifting out of Park
Common Causes
- Faulty brake light switch
- Open or short in the brake switch circuit wiring
- Corroded or loose electrical connectors to the brake switch
- Malfunction in the Powertrain Control Module (PCM) (less common)
- Incorrectly adjusted brake switch
Frequently reported on: General/Universal
Diagnostic Steps
- Locate the brake light switch, typically mounted on the brake pedal arm under the dash.
- Inspect the switch and its wiring for any visible damage, corrosion, or loose connections.
- Test the brake lights operation with the ignition on to confirm if they are functioning correctly.
- Using a multimeter, test the continuity and voltage at the brake switch connector to ensure proper electrical signals.
- If the switch is deemed faulty, carefully remove the old switch and install a new one, ensuring it is properly adjusted.
- Clear the P0571 code using an OBD-II scanner and retest the vehicle to confirm the repair.
👨🔧 When to Call a Professional
If, after inspecting and potentially replacing the brake switch, the code persists or if you suspect a complex wiring issue or a problem with the Powertrain Control Module (PCM), it is highly recommended to consult a professional mechanic for advanced diagnostics.
Commonly Asked Questions
What does brake switch 'A' circuit mean?
The 'A' refers to a specific circuit or input from the brake switch to the vehicle's computer, indicating a general malfunction in that electrical path.
Can I drive with a P0571 code?
While the car may still drive, it is not recommended to drive for an extended period, especially if your brake lights are not working or if the cruise control does not disengage, as this poses a significant safety risk.
Is the brake switch difficult to replace?
For most vehicles, replacing the brake switch is a relatively straightforward DIY task that involves basic tools and can be done in under an hour.
Will replacing the brake switch fix my cruise control?
Yes, often a faulty brake switch is the reason cruise control fails to engage or disengage, as the cruise control system relies on the brake switch signal.
How do I test the brake switch?
You can test the brake switch by checking if your brake lights illuminate when the pedal is pressed. For a more thorough test, use a multimeter to check for continuity or voltage at the switch's terminals when the pedal is pressed and released.