Cruise Control On Signal Malfunction
Your car's cruise control isn't responding when you press the button, similar to a TV remote that won't change the channel even though the batteries are fine. The ECU detected an electrical signal problem in the cruise control circuit.
The ECM monitors the voltage signal from the cruise control switch when activated. It expects a specific voltage change (typically 0V to 5V) when the button is pressed. If the signal is absent, erratic, or stuck at one level, the ECU logs a malfunction.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Cruise Control Switch Voltage | 0V (off) to 5V (on) with clean transitions | No voltage change detected or voltage remains stuck below/above expected range |
| Signal Integrity | Clean on/off transitions without noise | Intermittent signal or continuous electrical noise detected |
Code P0566 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, P0566 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.