P0572 — Brake Switch “A” Circuit Low #

Note: The code description can vary depending on the vehicle manufacturer. Always refer to your OEM (Original Equipment Manufacturer) service manual for the most accurate definition.

Known description variations:

• Brake Switch “A” Circuit Low — (Generic/SAE)
• Brake Pedal Position/Brake Switch A Circuit Low Input — (Ford, GM)
• Brake Light Switch Circuit Low Voltage — (Hyundai, Kia)
• Stop Lamp Switch Circuit Low — (Toyota, Honda)

Summary of DTC P0572 #

DTC P0572 is an OBD-II diagnostic trouble code that means the Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a low voltage condition in the Brake Switch “A” circuit. The brake switch, sometimes called the stop lamp or brake pedal position switch, is a critical input for brake lights, cruise control operation, and certain transmission or safety system functions. When the circuit signal stays below a preset threshold, the ECM/PCM logs P0572 and may disable related systems as a precaution. This code typically points to a fault in the switch, its wiring, or connectors rather than a failure in downstream systems. Prompt diagnosis is important for safe vehicle operation.

Common Symptoms for Code P0572 #

When your vehicle registers P0572, you may notice several symptoms. Some are obvious, like non-working brake lights, while others—such as cruise control deactivation—can be less apparent. These symptoms may occur individually or together, depending on the vehicle and severity of the fault.

• Brake lights do not illuminate when pressing the pedal
• Cruise control system is inoperative or disengages unexpectedly
• Transmission may not shift out of “Park” (on some models with shift interlock)
• ABS (Anti-lock Braking System) or traction control warning lights illuminated
• Check Engine or Service Engine Soon light is on
• Possible difficulty starting the vehicle (in rare cases)

Most Likely Causes for Code P0572 #

P0572 is most frequently caused by issues in the brake switch circuit rather than complex control modules. Some causes are very simple to address, while others may require more in-depth diagnosis. Here is the likely order of occurrence:

1. Faulty or misadjusted brake light switch
2. Damaged wiring or poor electrical connections at the brake switch
3. Corroded or loose brake switch connector
4. Blown fuse in the brake light or stop lamp circuit
5. Faulty brake light bulbs causing circuit feedback (less common)
6. ECM/PCM internal fault (rare)

Step-by-Step Diagnostic for P0572 #

Diagnosing P0572 can be straightforward with a systematic approach. Always begin with the basics before considering less common issues. Here is a master technician’s recommended step-by-step checklist:

1. Verify the code with a scan tool and check for related codes (ABS, cruise, etc.)
2. Check if brake lights illuminate when pedal is pressed. If not, inspect bulbs for function and proper installation.
3. Locate the brake switch (usually above the brake pedal) and inspect for physical damage, misalignment, or loose mounting.
4. Test the brake switch using a multimeter: verify power and ground at the connector, and check switch operation (continuity when pressed).
5. Visually inspect the wiring harness for chafing, pinched wires, or corrosion at connectors.
6. Check for blown fuse in the brake light or stop lamp circuit; replace if necessary.
7. If all checks pass but the code remains, use a scan tool with live data to monitor brake switch status. If the ECM/PCM doesn’t see the switch change state, suspect switch or wiring fault.
8. As a final step, if all components test good, consider ECM/PCM testing or replacement (rare).

Possible Repairs for Code P0572 #

Once the root cause is identified, repairs for P0572 are usually straightforward. Always use quality components and OEM procedures for best results.

• Replace faulty or worn brake switch with a new OEM or quality equivalent part
• Repair or replace damaged/brake switch wiring harnesses or connectors
• Clean and secure electrical connectors to remove corrosion and ensure solid connection
• Replace blown fuse(s) and verify cause for fuse failure
• Replace incorrectly installed or faulty brake light bulbs
• In rare cases, reprogram or replace the ECM/PCM if confirmed faulty

Is It Safe to Drive with P0572? #

Driving with code P0572 is generally not recommended. If your brake lights are not working, you are at serious risk of rear-end collisions because drivers behind you cannot see when you are braking. Additionally, cruise control and other safety features may be disabled. While the vehicle may technically still run, for your safety and the safety of others, address this code before further driving. If you must move the vehicle, use caution and consider using hazard lights as a temporary measure.

Vehicles Most Commonly Affected by P0572 #

While P0572 can appear on any OBD-II equipped vehicle, it’s commonly reported on models where brake switch design or placement makes it vulnerable to wear. Some examples include:

• Ford F-Series (F-150, F-250, etc.)
• Chevrolet Silverado, GMC Sierra
• Honda Accord, Honda Civic
• Toyota Camry, Toyota Corolla
• Hyundai Elantra, Hyundai Sonata
• Volkswagen Jetta, Passat

However, this code is not limited to these brands—any vehicle with a brake switch circuit can log P0572.

Common Mistakes & Best Practices with P0572 #

Misdiagnosis or skipping steps can lead to wasted time and parts. Here are typical errors and how to avoid them:

• Replacing the brake switch without checking if the fuse or bulbs are at fault
• Assuming the switch is bad when the issue is a corroded connector or broken wire
• Installing aftermarket parts of questionable quality—always opt for OEM or reputable brands
• Ignoring the code, thinking it’s only related to brake lights, when it also affects cruise control and safety features
• Clearing codes without fixing the underlying problem—this will only result in the code returning

Quick FAQ: P0572 Brake Switch “A” Circuit Low #

Here are answers to some of the most common questions about P0572:

• Q: Will my car fail inspection with P0572?
  A: Yes, in most regions, a non-functioning brake light or a Check Engine Light caused by P0572 will result in inspection failure due to safety concerns.
• Q: Can I simply replace the brake switch myself?
  A: On many vehicles, replacing the brake switch is a straightforward DIY job if you follow OEM instructions. However, always test the system after replacement to verify proper operation and code clearance.
• Q: Why did the code appear after bulb replacement?
  A: Installing the wrong type of bulb or a bulb incorrectly can cause circuit faults and trigger P0572. Double-check that bulbs are correct and properly seated.