Brake Light Switch Circuit Fault
Indicates a fault in the brake light 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 light switch is either faulty or not sending correct signals to the computer, which could fail to turn on brake lights or affect other systems like cruise control.
What the computer is actually seeing
The engine control module monitors the voltage from the brake light switch circuit, expecting about 0V when off and around 12V when on. A consistent voltage within that range signifies normal operation.
What a healthy reading looks like
0V (brake released), 12V (brake applied)
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 lights: Are they functioning properly? If yes, the switch may be fine. If not, continue.
- 22. Inspect the brake light switch wiring: Look for any frayed wires or poor connections. Repair as necessary.
- 33. Test the brake light switch: Use a multimeter to check for continuity and the expected voltage levels. Should show 0V when released and 12V when applied.
- 44. If the switch is faulty, replace it and clear the code. If it still happens and the switch is okay, further diagnose the circuit back to the ECM.
Common causes
- Faulty brake light switch
- Corroded or damaged wiring
- Poor connections at the switch or module
Typical repair cost
$$
Related codes
Frequently asked questions
Can I drive with this code?
Yes, but be aware that your brake lights might not function, which is a safety hazard.
Will this come back after repairs?
If you've fixed the underlying issue, it should not return. Monitor it after repairs.
Why did this code appear with another SPN code?
Additional codes may indicate related circuit issues, especially if multiple systems are impacted.
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