P0572 is an OBD-II trouble code that points to a problem in your cruise control brake switch circuit. In plain terms, your car’s computer is seeing a low voltage signal where it expects a normal one, so it disables or limits cruise control for safety. While this code usually won’t leave you stranded, it can be annoying and may hide more serious brake light or switch issues. Understanding what P0572 means, how it shows up, and how to track it down will help you decide whether it’s a DIY job or one for a shop.
What Does P0572 Mean?
P0572 stands for “Cruise Control/Brake Switch ‘A’ Circuit Low.” Your ECU (engine control unit) monitors the brake pedal switch to know when you’re braking. That same signal is used to cancel cruise control. When the ECU detects lower than expected voltage in that circuit, it sets P0572 and often disables cruise control to prevent unsafe operation.
This code is usually electrical, not mechanical. It’s commonly caused by a faulty brake light switch, wiring issues at the pedal, or a misadjusted switch that doesn’t change state correctly when you press the brake.
Quick Reference
- Code: P0572 – Cruise Control/Brake Switch “A” Circuit Low
- Main system affected: Cruise control and brake switch circuit
- Typical symptoms: Cruise inoperative, brake lights issues, warning lights
- Common causes: Bad brake switch, wiring fault, blown fuse, misadjustment
- Severity: Low to moderate – safety-related but usually drivable
Real-World Example / Field Notes
In the shop, I see P0572 most often on commuter cars and SUVs where the owner complains that cruise control suddenly stopped working. Many times, they never noticed the brake lights were acting up. After scanning the car, P0572 is stored, sometimes along with a brake light circuit code. A quick check under the dash reveals a worn or cracked brake switch at the pedal, or a connector half hanging out. Replace or adjust the switch, clear the code, and cruise control comes back to life. On some vehicles, corrosion at the connector is the real culprit.
Symptoms of P0572
- Cruise control inoperative – Cruise won’t set or turns off immediately after setting.
- Intermittent cruise operation – Cruise works sometimes, then drops out without you touching the brake.
- Brake lights malfunction – Brake lights stuck on, not coming on, or delayed response when pressing the pedal.
- Warning lights on dash – You may see ABS, traction control, or stability control lights along with the check engine light.
- Harder to maintain speed – No cruise control on long trips, leading to driver fatigue.
- Transmission shift oddities – On some vehicles, the TCM uses the brake signal; you might feel unusual downshifts or torque converter lockup behavior.
- Stored related codes – Other brake switch or cruise control codes may appear when scanned.
Common Causes of P0572
Most Common Causes
- Faulty brake light switch – The switch at the brake pedal is the number one cause. Internal contacts wear out, stick, or fail, sending the wrong voltage to the ECU.
- Misadjusted brake switch – If the switch isn’t positioned correctly against the pedal, it may not change state when you press or release the brake, causing a constant “low” signal.
- Damaged wiring at the brake pedal – Wires can get pulled, pinched, or broken near the pedal area, especially if aftermarket accessories were installed.
- Corroded or loose connector – Moisture, spills, or age can corrode the connector at the brake switch, increasing resistance and dropping voltage.
- Blown fuse or poor power feed – A fuse feeding the brake light or cruise control circuit can blow, or a poor contact in the fuse box can cause low voltage.
Less Common Causes
- Faulty cruise control switch assembly – On some designs, the brake signal passes through a multifunction or cruise module that can fail.
- Aftermarket wiring issues – Remote starters, trailer brake controllers, or alarm systems tapped into the brake circuit can introduce faults.
- Water intrusion at harness – Leaks from the windshield, sunroof, or firewall can corrode harnesses and connectors in the driver footwell.
- ECU or BCM internal fault – Rare, but the engine control unit or body control module can misread a good signal due to internal circuit failure.
- Incorrect bulb type or LED conversion problems – On some sensitive systems, incorrect brake light bulbs or poorly wired LED conversions can affect circuit voltage.
Diagnosis: Step-by-Step Guide
To diagnose P0572 properly, you’ll want a basic scan tool (preferably one that reads live data), a digital multimeter, a test light, and basic hand tools. Access to a wiring diagram or service info for your specific vehicle is also very helpful.
- Confirm the code and check for others. Connect your scan tool, read all stored and pending codes, and note any additional brake, ABS, or cruise-related DTCs. Clear the codes and see if P0572 returns quickly.
- Check brake light operation. With the ignition on, press and release the brake pedal while watching the brake lights (use a wall reflection or have someone help). If they don’t work correctly, focus on the brake switch and related wiring.
- Inspect the brake switch physically. Locate the switch at the top of the brake pedal arm. Look for broken housings, obvious damage, loose mounting, or a connector that isn’t fully seated.
- Verify switch adjustment. Many switches are threaded or clip-adjustable. Make sure the plunger contacts the pedal correctly and that the switch “clicks” or changes state as the pedal moves. A misadjusted switch can appear as a constant low signal.
- Test power and ground at the switch. Using a multimeter or test light, check for proper battery voltage on the power feed wire with the key on. Also verify a solid ground where applicable. No power means you need to trace back to fuses and upstream wiring.
- Check switch output voltage. Back-probe the signal wire from the switch to the ECU. You should see a clear change in voltage (often 0V to 12V or 0V to 5V depending on design) when pressing and releasing the brake. If the signal stays low, the switch is likely bad or the circuit is shorted to ground.
- Inspect wiring and connectors. If the switch tests good, follow the harness from the pedal toward the dash and firewall. Look for chafed insulation, pinched wires, or signs of water damage. Gently tug on wires at the connector to reveal hidden breaks.
- Use scan tool live data. Many vehicles show “Brake Switch Status” or similar in live data. Compare what the ECU thinks (ON/OFF) to what your foot is actually doing. If live data doesn’t change but the switch output does, suspect wiring between the switch and ECU or a control module issue.
- Advanced: Check Mode $06 or OEM tests. Some scan tools allow you to run specific brake switch or cruise control tests. This can help pinpoint marginal signals or intermittent faults.
- Rule out module failure last. Only after confirming good power, ground, switch function, and wiring continuity should you suspect the ECU or body module. At that point, professional diagnosis is recommended.
Pro tip: Lightly wiggle the brake switch connector and harness while watching live data or a test light. If the signal cuts in and out, you’ve likely found an intermittent connection that can be repaired without replacing major parts.
Possible Fixes & Repair Costs
Most P0572 repairs are straightforward and not terribly expensive. The exact cost depends on your vehicle, parts quality, and labor rates in your area.
- Replace brake light switch – The most common fix. Parts typically range from $20–$80, with 0.5–1.0 hour of labor. At a shop, you’re usually looking at $80–$200 total.
- Adjust brake switch – If the switch is good but misadjusted, a technician can reposition it. Often bundled into diagnostic time; expect $80–$150 for diagnosis and adjustment.
- Repair wiring or connector – Splicing in new wire, cleaning corrosion, or replacing a connector can run $100–$300 depending on access and severity.
- Replace fuse or repair power feed – A simple fuse replacement is cheap, but finding the cause of a repeatedly blown fuse can add labor time.
- Module replacement (rare) – Replacing an ECU or body control module can cost $500–$1,500+ including programming, but this is very uncommon for P0572.
Typical repair cost ranges for P0572 fall between $100 and $350 for most vehicles. Costs go up if additional issues are found, if interior trim must be removed for harness repairs, or if dealer-only programming is required.
Can I Still Drive With P0572?
In most cases, you can still drive with P0572, but you’ll likely have no cruise control and possibly abnormal brake light behavior. From a safety standpoint, the bigger concern is whether your brake lights are working properly. If they’re stuck off or on, other drivers can’t accurately see when you’re braking, which increases the risk of a rear-end collision. If you notice any brake light issue, avoid highway driving and get the problem fixed as soon as possible.
What Happens If You Ignore P0572?
If you ignore P0572, you may get used to driving without cruise control, but you risk ongoing brake light problems, intermittent ABS or traction control warnings, and potential inspection failures where functional brake lights and a clear check engine light are required. Over time, a minor wiring fault can worsen, leading to more codes or even a no-start if the affected circuit shares power feeds with other systems.
Related Codes
- P0574 – Cruise Control System Vehicle Speed Too High
- P0573 – Brake Switch “A” Circuit High
- P0571 – Brake Switch “A” Circuit
- P0570 – Cruise Control Accelerate Signal
- P0569 – Cruise Control Coast Signal
- P0568 – Cruise Control Set Signal
- P0567 – Cruise Control Resume Signal
- P0566 – Cruise Control Off Signal
- P0565 – Cruise Control On Signal
- P0564 – Cruise Control Multi-Function Input “A” Circuit
Key Takeaways
- P0572 means the ECU sees a low voltage signal from the cruise control/brake switch “A” circuit.
- The most common cause is a faulty or misadjusted brake light switch at the pedal.
- Symptoms usually include inoperative cruise control and possible brake light problems.
- Diagnosis focuses on the brake switch, its adjustment, power/ground, and wiring integrity.
- Most repairs are affordable, typically in the $100–$350 range at a typical repair shop.
- Driving is usually possible, but unsafe if brake lights are not working correctly.
Vehicles Commonly Affected by P0572
P0572 can show up on almost any OBD-II equipped vehicle, but it’s especially common on popular daily drivers with high mileage. You’ll often see it on:
- Ford – F-150, Escape, Focus, Fusion, Explorer
- Chevrolet / GMC – Silverado, Sierra, Malibu, Equinox, Tahoe, Suburban
- Chrysler / Dodge / Jeep / Ram – Ram 1500, Grand Cherokee, Wrangler, Charger, Caravan
- Toyota – Camry, Corolla, RAV4, Tacoma, Highlander
- Honda – Civic, Accord, CR-V, Pilot
- Hyundai / Kia – Elantra, Sonata, Tucson, Sportage, Sorento
These vehicles often see heavy stop-and-go use, which wears the brake switch and exposes wiring to more pedal movement and vibration.
FAQ
Can I clear P0572 and keep driving without fixing it?
You can clear P0572, and the car will usually drive, but the code will return if the underlying issue isn’t fixed. More importantly, you may be driving without proper cruise control or brake light function, which is a safety concern and can cause inspection failures.
Is P0572 always caused by a bad brake light switch?
No. The brake light switch is the most common cause, but wiring damage, loose connectors, blown fuses, and even aftermarket accessories tied into the brake circuit can all trigger P0572. That’s why basic testing with a multimeter and visual inspection is important before throwing parts at it.
How do I know if my brake switch needs adjustment or replacement?
If the brake lights stay on, don’t come on, or flicker when you lightly touch the pedal, the switch may be misadjusted or worn out. If adjusting its position doesn’t restore consistent operation, replacement is usually the best option. A scan tool showing erratic brake status in live data is another strong clue.
Can P0572 affect ABS or traction control?
Yes. Many ABS and traction systems rely on a clean brake pedal signal to know when you’re braking. If the ECU sees a faulty or low brake switch signal, it may disable or limit ABS, traction control, or stability control and turn on warning lights, even though the mechanical brakes still work.
How long does it take a shop to diagnose and fix P0572?
On most vehicles, a good technician can diagnose P0572 in about 0.5–1.0 hour. If the brake switch is clearly bad, replacement is usually another 0.3–0.5 hour. Wiring repairs or hard-to-reach components can extend that time, but many cars are in and out the same day.