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P codepowertrainLow severity

P0566Cruise Control Off Signal

The PCM has detected a fault in the cruise control Off signal, such as an implausible or constantly active cancel/off input.

Definition

The PCM watches the cruise control Off (or cancel) input so the driver can always disarm the system. P0566 sets when this signal is stuck active, missing, or inconsistent with the other switch inputs — for example an Off signal that stays asserted, which prevents cruise from ever engaging, or one that never appears when commanded. Because the off/cancel path is a safety interlock, the PCM disables cruise control while the fault is present. There is no driveability impact beyond inoperative cruise, and the MIL typically stays off.

Common causes

  • Faulty or sticking cruise Off/Cancel switch
  • Shorted wiring holding the Off signal active
  • Worn clockspring in the steering column
  • Misadjusted or faulty brake/clutch switch feeding the cancel logic on some designs
  • Corroded connector in the switch circuit
  • Faulty PCM input circuit (rare)

Common misdiagnoses

  • PCM or cruise module replaced for a sticking switch
  • Steering wheel switch pack replaced when the brake switch was misadjusted
  • Speed sensor replaced for cruise dropping out
  • Throttle actuator suspected for cruise refusing to engage

Troubleshooting steps

  1. 1.Observe the Off/Cancel input on a scan tool

    The PID should show active only while the button is pressed; a constantly active state explains cruise refusing to engage.

  2. 2.Check the brake and clutch switch inputs

    Verify the brake (and clutch, if manual) switch states toggle correctly on the scan tool, since many systems merge these into the cancel logic.

  3. 3.Test the Off switch resistance

    Measure the switch against the service chart in pressed and released positions, looking for sticking contacts or drifted resistance.

  4. 4.Inspect the clockspring and column wiring

    Check continuity through the column while turning the wheel and inspect connectors for corrosion or spread terminals.

  5. 5.Verify normal cancel behavior after repair

    Road test to confirm cruise engages, and that the Off button, brake pedal, and clutch (if equipped) each cancel it immediately.

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