English-first OBD-II diagnostics Static, fast, focused lookup pages
CD CheckDTC Garage-grade fault lookup
Open P0300 Try AI Diagnose
Home / Codes / P0571
DTC code page

P0571: Brake Switch A Circuit

Quick answer: The PCM sees an invalid or inconsistent signal on the primary brake-switch circuit.

Drivers also search this fault as brake switch a circuit, brake pedal switch a circuit, P0571 brake switch code.

Severity: medium Family: powertrain Related paths: 6
Meaning

What P0571 usually means

P0571 is a widely searched brake-switch code because it often shows up right when cruise control stops working or the vehicle develops an odd interlock complaint. The important part is that the engine computer is no longer confident in the main brake-switch input. On many vehicles that one signal is shared across cruise cancel strategy, torque management, and other logic that has nothing to do with illuminating the brake lamps alone. That is why a car can still stop normally yet store P0571 and behave strangely around cruise, throttle response, or transmission permissions.

Fast triage

Start here before chasing parts

  • Scan first: save freeze-frame and pending codes before clearing anything.
  • Confirm the complaint: compare the stored code with current drivability symptoms.
  • Use context: trims, live data, and related codes usually narrow the fault faster than guesswork.
  • Work simplest to hardest: leaks, connectors, maintenance items, and known patterns before expensive components.
Initial checks

What to check first

  • Check whether cruise control stopped working at the same time the code appeared because that pattern is classic P0571 behavior.
  • Inspect brake-lamp operation carefully, including whether the lights come on too late or stay on too long.
  • Look at the switch mount and pedal contact first if recent dash, booster, or pedal work was done.
Driving risk

Can you keep driving?

Most vehicles remain drivable with P0571, but brake-lamp reliability and cruise cancel logic matter. Fix it before treating the vehicle as fully sorted.

Moderate urgency: This code often allows short-term driving, but the right fix usually comes faster when you diagnose it early instead of waiting for more codes.
Symptoms

Common symptoms

  • Reduced Power
  • cruise control does not set
  • check engine light with brake switch fault
  • brake lights may be intermittent
  • shift interlock or stop lamp issues
Likely causes

Common causes behind this code

  • Failed brake-switch A circuit or worn internal switch contacts
  • Brake-switch connector looseness, corrosion, or terminal drag
  • Misadjusted switch not changing state at the correct pedal travel
  • Open circuit, high resistance, or fuse/feed issue in the stop-lamp or signal path
  • Module-side logic upset by low voltage or recent electrical work

Cause phrases often tied to this code: bad brake light switch, open circuit, connector issue, pedal adjustment, blown fuse.

Diagnostic order

Suggested workflow

  1. Verify the complaint: cruise cancel, lamp behavior, pedal travel, and any related ABS or traction warnings.
  2. Inspect the brake-switch connector, mounting, and adjustment at the pedal bracket.
  3. Check for clean power and ground on the circuit and verify the switch changes state reliably.
  4. Use scan data to confirm the PCM sees brake application when the pedal is pressed and release when it is not.
  5. Repair the switch or circuit fault and retest every affected function instead of only clearing the code.
Avoid guesswork

Common mistakes

  • Replacing the cruise switch or steering controls when the brake switch is the real reason cruise will not engage.
  • Testing brake lights once and assuming the switch cannot be intermittent.
  • Skipping adjustment checks and installing a new switch into the same bad pedal position.
Repair path

Practical fix guidance

  • Repair the confirmed switch, connector, fuse-feed, or adjustment fault behind the invalid brake input.
  • After repair, confirm cruise operation, brake-lamp timing, and normal code-free driving.
  • If multiple modules stored brake-input codes, verify the signal is stable across the system rather than only in the PCM.
Vehicle context

Affected brands in this MVP

Brand hubs help broaden internal linking now and can evolve into make-specific diagnostic notes later.

Aliases and common searches

English phrases tied to P0571

Useful when the driver knows the wording but not the exact DTC yet.

  • brake switch a circuit
  • brake pedal switch a circuit
  • P0571 brake switch code
Related search intent

Queries this page can answer naturally

  • P0571 code meaning
  • what does P0571 mean
  • brake switch A circuit
  • P0571 cruise control not working
FAQ

Quick questions about P0571

Can P0571 disable cruise control?

Yes. That is one of the most common real-world complaints tied to this code.

Will P0571 always make the brake lights fail?

No. The switch can be inconsistent enough to upset PCM logic while the lamps still appear to work much of the time.

Is the brake switch hard to diagnose?

Usually no, as long as you check pedal adjustment and signal behavior instead of assuming the first symptom tells the whole story.