P0571
UniversalCruise Control/Brake Switch A Circuit Malfunction
The brake-switch circuit provides a signal used by the vehicle to recognize brake-pedal operation, including when cruise control should disengage. This code means the vehicle detected a malfunction in the Switch A circuit; it does not prove that the switch itself has failed. Cruise control may be unavailable or behave unexpectedly, and brake-light operation may be affected if the circuit is shared.
⚠️ Before You Begin (Safety First)
Do not use cruise control until the fault is diagnosed. Check that the brake lights work before driving. If they do not work, stay off public roads and arrange repair, since other drivers may not be warned when you slow or stop. If the brake lights remain on, address that promptly as well.
Common Symptoms
- Cruise control may not engage because the vehicle detects a brake-pedal signal when the pedal is not pressed.
- Cruise control may disengage unexpectedly if the circuit signal changes intermittently.
- Cruise control may fail to disengage when the brake pedal is pressed if the vehicle does not recognize the brake signal; do not use cruise control with this fault.
- Brake lights may fail to illuminate, stay illuminated, or operate inconsistently if their function uses a related switch circuit.
- A warning light or stored diagnostic code may be present, though the vehicle may have no noticeable symptoms.
Common Causes
- A brake-pedal switch may be worn, misadjusted, damaged, or intermittently operating.
- A loose, corroded, or damaged connector may interrupt the switch signal.
- Wiring may be open, shorted, damaged, or making an intermittent connection.
- A circuit power or ground problem, including a relevant fuse issue where applicable, may interfere with the signal.
- The vehicle's control module may be receiving or interpreting an implausible signal; this requires circuit checks before a module fault is suspected.
Diagnostic Steps
- With the vehicle safely parked, ask someone to observe the brake lights while you press and release the pedal. Note whether they illuminate and turn off consistently.
- Check for obvious damage or looseness around the visible brake-pedal switch and its connector without forcing or adjusting the switch.
- Look for accessible wiring damage near the pedal area, such as chafing, pinching, or a connector that appears disconnected. Avoid probing connectors or altering wiring if you are unsure.
- If brake lights do not work, stay off public roads and arrange diagnosis. If the lights work but the code returns or cruise behavior is abnormal, have the circuit checked using vehicle-specific service information.
When to Call a Professional
A technician can compare brake-switch states in scan data while operating the pedal, then inspect and test the circuit using the vehicle-specific wiring information. Diagnosis should distinguish a switch or adjustment problem from a connector, wiring, power, or ground fault before any part is replaced.
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Commonly Asked Questions
Does P0571 prove the brake switch needs replacement?
No. It identifies a malfunction in the Cruise Control/Brake Switch A circuit. The switch, its adjustment, connector, wiring, or circuit supply and ground may need checking before deciding what to repair.
Can the vehicle still be driven with this code?
That depends on brake-light and cruise-control behavior. Do not use cruise control. If the brake lights do not work or stay on, do not drive on public roads until the problem is addressed.
Why might cruise control stop working when the brake lights seem normal?
The vehicle may use a brake-switch signal for cruise control that is not identical to the visible brake-light behavior. Scan data and circuit testing can help identify whether the signal is reaching the control system correctly.
Could this code appear without obvious symptoms?
Yes. An intermittent or implausible circuit signal may store a code even when no symptom is apparent at the time. Brake-light operation and cruise-control behavior should still be checked.
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