Faulty or misadjusted brake pedal switch or clutch pedal switch sending a stuck or implausible signal; Worn or faulty cruise control switch or steering wheel control (stalk, buttons or clock spring contacts); Wiring damage, corrosion or poor connection in the cruise control off or cancel signal circuit; Blown fuse or a supply or earth fault affecting the cruise control switch circuit; Faulty clock spring (spiral cable) on vehicles with steering wheel mounted controls; Fault inside the control unit or an outdated calibration, where the manufacturer has identified one for that model.

P0566

Cruise Control Off Signal.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
5: AreaVehicle speed, idle control and auxiliary inputs
66: FaultThe specific fault in that area

What it means

P0566 is the generic SAE J2012 code for a fault in the cruise control off signal circuit. The engine or powertrain control unit saw a cruise control off (cancel) input that was out of range, stuck, or did not match the other inputs it uses, such as the brake switch state or the cruise control master switch. How the check is made and what counts as a fault varies by vehicle.

Symptoms

Cruise control will not engage or set a speed
Cruise control cancels itself unexpectedly
Cruise control indicator light does not come on, or flashes
Malfunction indicator lamp may be on
Cruise control buttons on the steering wheel or stalk are unresponsive or intermittent

Possible causes

Faulty or misadjusted brake pedal switch or clutch pedal switch sending a stuck or implausible signallikely
Worn or faulty cruise control switch or steering wheel control (stalk, buttons or clock spring contacts)likely
Wiring damage, corrosion or poor connection in the cruise control off or cancel signal circuitpossible
Blown fuse or a supply or earth fault affecting the cruise control switch circuitpossible
Faulty clock spring (spiral cable) on vehicles with steering wheel mounted controlspossible
Fault inside the control unit or an outdated calibration, where the manufacturer has identified one for that modelrare

How to diagnose

Read the stored codes and freeze frame data, and note any other brake, cruise or network codes
Check that the brake lamps work and switch off properly, as a faulty brake switch often affects cruise control
Inspect the brake and clutch pedal switches for correct position, damage and a secure connector
Check the relevant fuses and inspect the cruise control switch, clock spring and connectors for damage, moisture or corrosion
Use live data to watch the cruise off or cancel signal and the brake switch status while pressing the pedals and operating each cruise control button
Test the signal circuit for voltage, earth and continuity against the manufacturer wiring diagram, and look for shorts or high resistance
Check for applicable service bulletins or calibration updates for the specific model and engine before replacing the control unit

How to fix

Replace or readjust the brake or clutch pedal switch
Replace the faulty cruise control switch or steering wheel control assembly
Repair damaged wiring or connectors, and clean or replace corroded terminals
Replace the blown fuse after finding and fixing the cause of the fault
Replace the clock spring if testing shows it is faulty
Update the control unit calibration only if a known fault applies, or replace the unit as a last resort after all else is ruled out

Can I keep driving?

Low severity

The car is normally safe to drive, but cruise control will probably be unavailable. If the brake lamps are not working correctly, get that fixed promptly, as it is a safety issue.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.