Brake Switch Circuit Fault
The brake switch is not providing the expected signal to the engine control unit (ECU).
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 computer when you press the brake pedal. If it’s broken or gets stuck, the computer won’t know you’re trying to stop the vehicle.
What the computer is actually seeing
The ECU expects to see either 0 volts (brake not pressed) or approximately 12 volts (brake pressed). If it sees fluctuating voltages or no voltage change, that triggers this code.
What a healthy reading looks like
0V when brake is not pressed, 12V when brake is pressed.
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.
- 1Check the brake fluid level; ensure it's not low.
- 2Inspect the wiring and connectors for the brake switch—look for damage or corrosion.
- 3Using a multimeter, check the voltage at the brake switch connector with the pedal not pressed (expect 0V) and pressed (expect 12V).
- 4If the readings are inconsistent, replace the brake switch.
- 5If the brake switch tests good, check wiring continuity back to the ECU.
Common causes
- Faulty brake switch
- Wiring issues
- Corroded or loose connectors
- Failed ECU
Typical repair cost
$$
Related codes
Frequently asked questions
Can I still drive the vehicle with this code?
Yes, but be cautious; your brake lights may not function properly.
Will this issue come back after resetting the code?
It might if the underlying problem isn't fixed.
Why does this code pair with SPN 231?
Both codes are related to the brake system; issues with the brake switch can affect multiple signals.
Working a real vehicle right now?
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