P0572
UniversalCruise Control/Brake Switch A Circuit Low
The vehicle’s control system has detected a lower-than-expected electrical signal in the cruise control/brake switch A circuit. The brake switch tells the vehicle when the brake pedal is pressed; that signal can also be used to cancel cruise control. The code does not prove that the switch itself has failed, and the exact effects depend on the vehicle.
⚠️ Before You Begin (Safety First)
Check that the brake lamps work before driving. If they do not work, or stay on continuously, do not drive until the problem is addressed because other road users may not receive a reliable braking signal. Avoid using cruise control until the fault is diagnosed. Stop safely if braking behavior changes.
Common Symptoms
- The check-engine or other warning light may be on.
- Cruise control may be unavailable or may not respond as expected if the vehicle relies on this signal to operate or cancel cruise control.
- Brake lamps may fail to illuminate or may remain illuminated if the affected switch circuit also serves that function; some vehicles use separate switch contacts or circuits.
- The vehicle may show no noticeable symptoms, with the code found during a scan.
Common Causes
- A brake switch may be faulty, worn, or out of adjustment, causing its signal to remain lower than expected.
- Damaged wiring or a connector with corrosion, looseness, or poor contact may affect the circuit signal.
- A short to ground or another wiring fault may pull the signal low; the exact interpretation depends on the vehicle’s circuit design.
- A power-supply or circuit connection problem may prevent the expected signal from reaching the control system.
Diagnostic Steps
- With the vehicle parked safely, ask someone to press and release the brake pedal while you check whether the brake lamps operate consistently.
- Look for obvious damage, loose connections, or corrosion at accessible brake-switch wiring and connectors; do not pull on wires or probe safety-system connectors.
- Check for related stored codes with a scan tool, and note whether the code returns after clearing it only if you can do so safely and follow the vehicle’s instructions.
- If the brake lamps do not work, stay on, or behave inconsistently, avoid driving and arrange diagnosis by a qualified technician.
- Use the vehicle-specific service information for further testing; do not bypass the switch or make unverified wiring changes.
When to Call a Professional
A technician can check related codes and scan data to see whether the brake-switch signal changes when the pedal is pressed, then compare that information with brake-lamp operation. If needed, use the vehicle-specific wiring diagram to test the switch and circuit for poor connections, unwanted grounding, or a power-supply problem. The code alone is not a reason to replace a part.
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Commonly Asked Questions
Does P0572 mean the brake switch must be replaced?
No. It reports a low signal in the brake switch A circuit, not a confirmed failed part. The switch, its adjustment, wiring, connectors, or circuit supply may need to be checked.
Can I drive with this code?
First confirm that the brake lamps work reliably. If they do not work, stay on, or behave inconsistently, do not drive until the issue is addressed. Avoid cruise control until the fault is diagnosed.
Why might there be no obvious symptoms?
The fault may affect a signal used mainly by cruise control or vehicle controls, and some vehicles use separate switch contacts for different functions. A scan may reveal the condition before the driver notices a change.
What does “circuit low” identify?
It means the control system detected a signal lower than expected in the named circuit. It does not, by itself, identify the failed component or prove a short to ground.
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