Cruise Control Input Circuit High
The cruise control system is receiving a voltage signal that's too high, like a stuck accelerator pedal sending constant maximum signal. The ECU can't properly read your cruise control inputs because the circuit is malfunctioning.
The ECU monitors the cruise control input voltage through the accelerator pedal position sensor or cruise control switch circuit. When voltage exceeds the maximum threshold (typically above 4.5V on a 5V reference), the ECU logs a fault. This prevents erratic cruise control engagement that could cause safety hazards.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Cruise Control Input Voltage | 0.5V to 4.5V (depending on switch state) | Above 4.5V or shorted to battery voltage |
| Signal Continuity | Continuous valid signal transitions | Stuck high or open circuit condition |
Code P0577 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, P0577 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.