What it means
The control module monitors the cruise control off signal and sets this code when the signal is missing or outside its expected electrical or operating range. The fault can prevent the module from recognizing an off command.
At a glance
- Usually lights the check-engine light
How it works
The cruise-control off switch sends a signal for the control module to cancel cruise control. P0566 sets when the module cannot recognize that off command because the signal is missing or outside its expected electrical or operating range.
Common causes
Most likely first.
- Switch contact defective
- Wiring fault
Symptoms
- Cruise control may not disengage when commanded
- Cruise control may not engage
- Cruise control buttons may respond inconsistently
- Check-engine light may come on
How to diagnose it
- Review freeze-frame data and related cruise-control codes to establish when the off-signal fault occurred.
- Use scan-tool live data to watch the cruise-control off status while pressing and releasing the off switch.
- Inspect the off switch or stalk, connector, and nearby wiring for damaged parts, loose pins, or corrosion.
- Test switch contact operation and the off-signal circuit for opens, shorts, or intermittent connections using the wiring diagram.
- If the switch and circuit pass, check the receiving module's power, grounds, and input response according to the manufacturer's procedure.
Common fixes
- Clean or reconnect a loose or corroded off-switch connector.
- Repair an open, short, or damaged wire in the cruise-control off-signal circuit.
- Replace a defective cruise-control off switch or stalk.
- Repair the related control module or its connections if testing shows it is not recognizing a valid signal.
Can I keep driving?
Do not use cruise control until the off command reliably cancels it. If it does not disengage, use the brake to cancel cruise and stop safely if the system remains engaged.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.