Cruise Control/Brake Switch A Circuit Malfunction
Your car's cruise control brake switch isn't communicating properly with the engine computer. Think of it like a light switch that's stuck or broken—the ECU can't tell if you're pressing the brake pedal or not.
The ECU monitors voltage levels from the brake switch circuit to detect when the brake pedal is pressed. When brakes are applied, the switch should signal the ECU to deactivate cruise control immediately. The ECM checks for proper voltage transitions and circuit continuity to ensure safe operation.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Brake Switch Voltage | 0V when pedal pressed, 5V when released | No voltage change or stuck at one level |
| Circuit Resistance | Less than 5 ohms when engaged | Open circuit (infinite ohms) or short condition |
Code P0572 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0572 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.