Brake Switch Signal
The brake switch signal is out of range or missing.
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 computer checks if the brake pedal is pressed using a switch; if that signal is missing or wrong, it sets this code.
What the computer is actually seeing
The brake switch should send a signal between 0 and 5 volts when pressed. A reading outside this range or no signal at all will trigger this code.
What a healthy reading looks like
Normal operation should show 0 volts (off) when brake is not pressed, and near 5 volts (on) when 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.
- 11. Check wiring and connectors at the brake switch for damage or corrosion.
- 22. Measure the voltage at the brake switch while pressing the pedal. You should see a change from 0 volts to near 5 volts.
- 33. If the voltage does not change, replace the brake switch.
- 44. If the switch is good, check for damaged wiring or loose connections leading to the ECM.
Common causes
- Faulty brake switch
- Wiring issues or shorts
- Poor connections at the brake switch
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Moderate severity means fix soon; check brake lights. Driving might be risky without functional brakes.
Will this code come back after clearing?
If the issue isn't fixed, the code will likely return.
Why does this code pair with SPN 156 or SPN 157?
These codes also relate to the brake system, indicating potential interconnected faults.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →