Brake Switch A Circuit Low
The brake pedal position sensor signal is lower than expected.
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 sends a low voltage signal to the engine control module (ECM) when you press the brake pedal, but it's not sending enough voltage, indicating a possible issue with the switch or wiring.
What the computer is actually seeing
The ECM expects to see a voltage between 0.5V and 5V from the brake switch when the brake pedal is pressed; anything below 0.5V triggers this code.
What a healthy reading looks like
Expected voltage from brake switch is typically around 0.2V when off and 1.0-4.5V when pressed; can vary by vehicle.
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.
- 1Confirm that the vehicle's brake lights are functioning properly; if not, check the brake switch first.
- 2Inspect the wiring and connectors leading to the brake switch for damage or loose connections; repair if necessary.
- 3Using a multimeter, measure the voltage at the brake switch connector; it should be near battery voltage (12V) when the pedal is not pressed and below 0.5V when pressed. If not, replace the switch.
- 4If the switch is functioning correctly, trace the wiring back towards the ECM for any breaks or shorts. Testing for continuity may help locate the issue. If all checks out, consider the ECM itself.
Common causes
- faulty brake pedal switch
- damaged wiring or connectors
- corrosion in the connector
- incorrect brake switch adjustment
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code active?
It's generally drivable, but you may experience issues with cruise control and adaptive systems relying on proper brake signal.
Will this code come back after I clear it?
It can return if the underlying issue is not resolved, like a faulty switch or wiring problem.
Why does this code sometimes appear with other codes?
It can be paired with other codes related to the brake system or cruise control, as they all depend on the brake switch signal.
Working a real vehicle right now?
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