OBD-II Code P0572 — What It Means & How to Fix It

What Does This Error Mean?

P0572 means the PCM detected a low voltage condition in cruise control and brake switch circuit A. The brake switch tells the PCM when you press the brake pedal — this immediately cancels cruise control and also controls brake lights. A low circuit signal usually means the switch is stuck in the pressed position, the wiring is shorted to ground, or the switch has failed. This is more than just a cruise control issue — a bad brake switch also affects brake lights and ABS operation on many vehicles.

Affected Models

Any 1996 and newer vehicle with PCM-monitored cruise control and brake switch circuit
Ford and GM trucks — brake switch circuit issues are common on high-mileage models
Toyota and Honda vehicles where the brake switch serves multiple systems simultaneously
Chrysler, Dodge, and Jeep vehicles where the brake switch affects ABS and stability control
European vehicles where the brake switch is integrated into multiple safety systems

Common Causes

Brake light switch has failed in the closed (depressed) position — sending a constant active signal to the PCM
Brake switch signal wire is shorted to ground — causing the circuit to read a permanently active state
Brake switch is misadjusted — positioned too close to the brake pedal arm so it activates without the pedal being pressed
Brake switch connector is corroded or has a short between terminals
Failed brake switch that sends low or erratic voltage signals during normal driving

How to Fix It

Check your brake lights. Have someone stand behind the vehicle while you press and release the brake pedal. Brake lights that stay on constantly (even without pressing the pedal) confirm the switch is stuck closed. Brake lights that do not work at all confirm the switch is open or failed.

Stuck-on brake lights will drain your battery overnight and can confuse drivers behind you — fix this promptly.
Locate the brake light switch on the brake pedal arm above the pedal. It is usually a small rectangular switch mounted on a bracket near the top of the pedal. Check if it is properly adjusted — the switch plunger should contact the pedal arm bracket and release cleanly when the pedal is released.

On many vehicles the brake switch has an adjustment — a small turning or sliding mechanism. Refer to your service manual for the correct gap specification.
Adjust the brake switch if misadjustment is suspected. The correct position has the plunger just barely contacting the pedal arm when the pedal is at rest. Too close and it reads as always pressed; too far and it never activates.

After adjustment, retest brake lights and cruise control cancel function before reassembling any trim.
Test the switch electrically. With the connector disconnected and the pedal at rest, the switch should show open or closed depending on its normal-state design. Press the pedal and it should switch. No change in state confirms switch failure.

Many brake switches are inexpensive — $15 to $40 for the part. If the switch fails testing, just replace it.
Check the wiring between the brake switch and PCM for a short to ground. Disconnect the switch and probe the signal wire against chassis ground with a multimeter. Continuity to ground with the switch disconnected means the harness has a short that needs repair.

After repairing or replacing, clear the code, confirm brake lights work correctly, and test cruise control cancel function.

When to Call a Professional

The brake switch is an important safety component — it operates the brake lights, cancels cruise control, and enables ABS and stability systems. If your brake lights are stuck on or off, have this repaired immediately — stuck-on brake lights drain the battery and create a safety hazard. Brake switch replacement is typically $75 to $200 at a shop.

Frequently Asked Questions

Can a bad brake switch prevent cruise control from engaging?

Yes — if the PCM sees a constant brake signal (stuck switch), it will not allow cruise control to engage because it thinks the brake is being pressed. The PCM is designed to cancel cruise control when it detects brake pedal application. A stuck brake switch signal effectively prevents cruise from activating at all.

Will P0572 affect my ABS or stability control?

On many vehicles, yes. The brake switch signal is used by the ABS and stability control modules to confirm a driver-commanded braking event. A faulty switch can cause those systems to behave incorrectly or trigger their own warning lights. Repairing the brake switch usually resolves multiple warning lights at once.

How long does brake switch replacement take?

Usually 30 to 60 minutes including testing. The switch is accessible under the dashboard near the brake pedal — no special tools required in most cases. It is one of the more straightforward repairs a DIYer can do, as long as you are comfortable working under the dash.