Brake Switch A Circuit Malfunction
The brake switch circuit has a fault.
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 that tells the computer when you press the brake pedal isn't working right. It should show a closed circuit when the pedal is pressed, but it's reading incorrectly instead.
What the computer is actually seeing
The brake switch is expected to close a circuit (0 volts) when the brake pedal is pressed and open when it's not (5 volts).
What a healthy reading looks like
When the brake pedal is not pressed, there should be around 5 volts at the brake switch signal wire. When pressed, it should drop close to 0 volts.
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.
- 11. Check the brake switch connector for damage and ensure it's firmly connected. If damaged, repair or replace the connector.
- 22. Using a multimeter, test the brake switch output: disconnect the switch and measure voltage at the harness connector. Should be about 5 volts with no pedal press. If not, check wiring back to the PCM.
- 33. Press the brake pedal and re-check the voltage; it should drop to near 0 volts. If it does not, replace the brake switch.
- 44. If the switch tests okay, inspect the wiring and connectors for any signs of damage or corrosion. Repair as needed.
- 55. If all else is fine, check the PCM for faults in the brake input circuitry.
Common causes
- Faulty brake switch
- Damaged wiring or connectors in the brake switch circuit
- Faulty brake pedal position sensor
- Electrical short or open in the circuit
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but be cautious as your brake lights may not function properly, which can be a safety issue.
Will this code return if I clear it?
It may return if the underlying issue isn't fixed, such as a faulty brake switch or wiring problem.
Why does this code sometimes pair with C0520?
C0520 is related and indicates a similar fault, suggesting issues in the braking system circuit.
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