The P0572 code is a generic OBD-II powertrain code indicating a “Cruise Control/Brake Switch A Circuit Low” condition. The powertrain control module detected an unexpectedly low voltage signal in the primary brake switch circuit.
This code does not automatically prove the brake switch has failed. Wiring faults, connector issues, or switch misadjustments can also cause this circuit condition, requiring proper electrical testing before any parts are replaced.
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Key Takeaways
- P0572 is a generic code indicating a low voltage condition in the brake switch A circuit.
- The brake switch controls cruise control cancellation, brake lights, and torque converter clutch operation.
- Possible causes include a misadjusted switch, short to ground, or damaged wiring.
- Diagnosis requires verifying brake light operation and checking live data switch states.
P0572 Code Description and Implications
The P0572 code sets when the powertrain control module (PCM) detects a low voltage condition in the brake switch “A” circuit. This switch serves multiple critical functions beyond simply illuminating the brake lights.
It signals the PCM to disengage the cruise control, prevents the torque converter clutch from locking, and informs the transmission control module during gear shifts. Some vehicles use a dual-circuit switch configuration.
Because this is a generic code, the fundamental definition remains consistent across manufacturers. However, the exact diagnostic procedure, wiring colors, and pinout specifications will vary depending on your specific vehicle application.
Common Causes of the P0572 Code
A misadjusted or improperly installed brake light switch is a verified cause. If the switch plunger does not fully extend when the pedal is released, the PCM may read a continuous low-voltage signal.
Wiring damage is another verified cause. The harness routing near the brake pedal is subject to constant movement and can chafe against metal brackets, creating a short to ground in the signal circuit.
Corroded connectors or pushed-out pins at the switch or PCM can also drop the circuit voltage. In rare cases, an internal PCM fault may prevent the module from properly reading the switch state.
Symptoms Associated With P0572
A noticeable symptom is the cruise control system refusing to engage or unexpectedly disengaging. The PCM disables cruise control if it cannot reliably verify the brake switch status.
You may also experience harsh transmission shifts or a failure of the torque converter clutch to lock or unlock. The PCM relies on the brake switch signal to manage transmission line pressure.
Depending on the vehicle, the brake lights may remain illuminated continuously, fail to illuminate, or operate normally if the vehicle uses a separate circuit. The Check Engine Light behavior varies by application.
Diagnosing the P0572 Trouble Code
Begin by verifying the exact factory definition for this error code and checking for related codes. Next, physically inspect the brake lights to confirm they operate correctly when the pedal is pressed and turn off when released.
Connect a scan tool to view the PCM live data for the brake switch state. The data should toggle between released and applied as the pedal is operated to verify switch logic.
If the live data does not change, use a multimeter to test the switch reference voltage, signal circuit continuity, and ground connections according to the manufacturer wiring diagram for your specific vehicle.
Repairing the P0572 Issue
If the brake switch is found to be out of adjustment, resetting the plunger depth to the manufacturer specification may resolve the issue. Some modern switches require a specific installation procedure to self-adjust.
If testing confirms a short to ground in the wiring harness, the damaged section must be repaired or replaced, and the circuit retested for proper voltage and continuity before reassembling the pedal area.
If the switch fails electrical testing, replace it with a component meeting the correct vehicle specification. After any repair, clear the codes and verify the live data toggles correctly during a test drive.
Cost Considerations for P0572 Repairs
Cost depends on diagnostic time, component accessibility, and required parts. Replacing an externally mounted brake switch near the pedal assembly is a straightforward job with minimal labor time.
However, if the fault traces back to a damaged wiring harness deep within the dashboard or requires PCM reprogramming, diagnostic and repair times will increase. Always confirm the root cause before purchasing parts.
Prevention Strategies for Future Occurrences
Inspecting the wiring harness near the brake pedal pivot can help identify developing chafing or insulation damage before it causes a short circuit in the brake switch signal path.
Ensuring that no aftermarket floor mats interfere with the brake pedal travel prevents the switch plunger from being damaged or forced out of its proper adjustment range during normal driving.
Keeping the pedal assembly area clean and free of excessive moisture reduces the risk of connector corrosion over time, helping maintain reliable electrical contact for the switch circuits.
Troubleshooting Tips and Best Practices
Always check for technical service bulletins specific to your vehicle. Some manufacturers have issued updated switch designs or revised PCM software calibrations to address overly sensitive brake switch monitors.
Do not assume a bad switch without checking the wiring. The constant flexing of the pedal harness makes it a high-wear area for broken wires or shorts to ground.
If your vehicle uses a dual-circuit switch, remember that the brake lights might work perfectly even if the PCM cruise control circuit has failed. Rely on scan tool live data rather than visual checks.
More OBD-II Codes
| P0571 | P0563 | P0562 | P0560 |
| P0556 | P0551 | P0573 | P0579 |
| P0581 | P0597 | P0598 | P0599 |
| P0703 | P0504 | P0700 | P0500 |
| P0520 | P0522 | P0524 | P0526 |
| P0532 | P0533 | P0540 | P0542 |
Frequently Asked Questions
Is P0572 a generic or manufacturer-specific code?
P0572 is a generic OBD-II code. Its fundamental definition as a brake switch circuit low condition applies across all vehicle makes, though exact diagnostic steps vary by manufacturer.
Can a bad brake switch cause transmission shifting issues?
Yes. The PCM uses the brake switch signal to manage torque converter clutch operation and transmission line pressure. A faulty signal can cause harsh shifts or prevent the torque converter from locking.
Will my brake lights still work with a P0572 code?
It depends on the vehicle. Many modern vehicles use a dual-circuit switch where one circuit controls the brake lights and the other signals the PCM. The lights may work even if the PCM circuit fails.
Does clearing the code fix the P0572 issue?
No. Clearing the code only resets the system memory. If the underlying electrical fault, misadjustment, or wiring short remains, the PCM will detect the condition and set the code again.
Can a misadjusted floor mat trigger P0572?
Yes. If a thick or improperly placed floor mat wedges under the brake pedal, it can prevent the pedal from fully returning to its resting position, keeping the brake switch plunger depressed and triggering a circuit low code.
What Should You Do About the P0572 Code?
Confirm the exact factory diagnostic procedure for your specific vehicle application. Because the brake switch interacts with cruise control, transmission operation, and vehicle safety systems, accurate electrical testing is essential.
Inspect the switch adjustment, verify the live data states with a scan tool, and test the relevant system and components for shorts or opens before replacing any parts to ensure proper repair.
