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SPN 1571moderate severity✨ AI-generated

Brake Switch Circuit Failure

Indicates a fault in the brake switch circuit.

Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.

What it means (plain English)

The brake switch tells the engine control unit when you press the brake pedal. If it's faulty, your system won't know when you're braking.

What the computer is actually seeing

The ECU monitors inputs from the brake switch. A failure to send expected signals (like 12V when pressed) generates this fault.

What a healthy reading looks like

When brake pressed, the signal should be around 12V; when released, close to 0V.

Guided diagnostic — the DiagCoach way

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

  1. 11. Check the brake fluid level; refill if low. Decision: Is fluid level adequate? Yes: proceed. No: top off and retest.
  2. 22. Inspect wiring and connectors at the brake switch for damage or corrosion. Decision: Are the connections secure and clean? Yes: proceed. No: repair connections and retest.
  3. 33. Test the brake switch using a multimeter. With the pedal pressed, check for ~12V. Decision: Is voltage present? Yes: check wiring back to the ECU. No: replace the brake switch.

Common causes

  • Faulty brake switch
  • Wiring issues in the brake switch circuit
  • Corroded or loose connectors

Typical repair cost

$$

Related codes

Frequently asked questions

Can I still drive the vehicle with this code?

You can drive, but fix this soon to ensure brakes function correctly.

Will this code come back after I clear it?

If the underlying issue isn't fixed, it will return.

Does this relate to the cruise control not working?

Yes, a faulty brake switch can disable cruise control.

Working a real vehicle right now?

Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.

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