Brake Switch A Circuit Intermittent
The brake light switch signal is inconsistent or unstable.
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 sending a steady signal to the computer; it might turn on and off when it shouldn't, causing potential issues with cruise control and other systems.
What the computer is actually seeing
The engine control module (ECM) expects a steady voltage from the brake switch. This signal is typically either about 0.5 volts (off) or 12 volts (on). If the signal fluctuates, it triggers the P0574 code.
What a healthy reading looks like
When the brake pedal is not pressed, the brake switch should read around 0.5V; when pressed, it should go up to around 12V.
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; low fluid can affect switch operation. Is it within the proper range? (Yes: proceed; No: top off fluid and recheck code)
- 2Inspect the brake light switch; visually check for any physical damage. Is it intact? (Yes: proceed; No: replace the switch)
- 3Test the brake switch with a multimeter; should show 0.5V when not pressed and around 12V when pressed. Do you see these readings? (Yes: check wiring; No: replace the switch)
- 4Inspect wiring and connectors between the brake switch and the ECM for shorts or corrosion. Are they in good condition? (Yes: check ECM; No: repair the wiring)
- 5Check for ECM software updates that might address this code. Is the software version current? (Yes: further diagnosis needed; No: update and retest)
Common causes
- Faulty brake light switch
- Wiring issues in the brake switch circuit
- Bad connector at the brake switch
- ECM software issue
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but avoid using cruise control as it may not function properly.
Will this code come back if I clear it?
If the underlying issue isn't fixed, yes, it will likely return.
Why does this code pair with P0571?
P0571 relates to the brake switch circuit, which may exhibit similar intermittent issues.
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