Brake Light Circuit Malfunction
There's a problem in the brake light 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 light switch isn't working right, which means your brake lights might not turn on when you press the pedal.
What the computer is actually seeing
The body control module (BCM) expects a specific voltage signal when the brake pedal is pressed. If it sees 0 volts (no signal) when it should see 12 volts (signal active), it sets the code.
What a healthy reading looks like
When the brake pedal is not pressed, the voltage should be near 0 volts. When the pedal is pressed, the voltage should jump to around 12 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 brake light function. Are the brake lights working?
- 2 - Yes: Proceed to step 2.
- 3 - No: Check the fuse and wiring; repair as needed.
- 42. Inspect the brake light switch. Is it properly connected and not damaged?
- 5 - Yes: Proceed to step 3.
- 6 - No: Replace the brake light switch.
- 73. Measure the voltage at the brake light switch connector when the pedal is pressed. Is it around 12 volts?
- 8 - Yes: Look for issues in the wiring to the BCM.
- 9 - No: Replace the brake light switch.
Common causes
- Faulty brake light switch
- Broken wiring or connector
- Corroded terminals
- Blown fuse for brake lights
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It may not be safe, as your brake lights might not function, which can lead to accidents.
Will this code come back after clearing it?
It can, especially if the underlying issue isn't fixed.
Why does it pair with other B codes?
Codes related to the brake system often trigger together due to common components.
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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