Cruise control buttons are almost always a resistor ladder on one or two signal lines, each button giving its own voltage; the module reading it (GM and Saab from about 2010: the body module; FCA: steering column module or PCM) sends the button state to the engine module over CAN. CARB names cruise control as the example of an emission-neutral diagnosis – it is simply switched off – so GM lists all these codes as type C and Ford as non-MIL: no warning lamp, the engine runs normally. P0566 concerns the off signal of the main switch – implausible, stuck or invalid. No manufacturer document available to us uses this code. GM reports the on/off button under P0565 and the cancel button under P056C.
Low severity. Can I keep driving?You can keep driving, but check that the brake lights work: that part is a safety issue.
Symptoms
- Cruise control cannot be switched on or off
- Cruise control locked out
- No check engine light, engine runs normally
Most likely causes
- On/off button stuck or faulty
- Moisture or wear in the steering wheel switch
- Contact resistance in clockspring or steering wheel connector
- Body module or cruise module
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
What each character of P0566 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 5: Speed and idle
- 66: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0566?
You can keep driving, but check that the brake lights work: that part is a safety issue.
What causes code P0566?
The most common causes are: on/off button stuck or faulty; moisture or wear in the steering wheel switch; contact resistance in clockspring or steering wheel connector.
Related codes
- P0565Cruise Control On Signal
- P056CCruise Control Cancel Signal
- P0564Cruise Control Multi-Function Input A Circuit
- P0567Cruise Control Resume Signal
- P0568Cruise Control Set Signal
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.