What causes fault code P0566?

• Most likely: Faulty cruise control switch/button assembly (mechanical failure or internal short) • Likely: Failed clock spring (spiral cable) behind the steering wheel causing intermittent signal loss • Possible: Wiring harness issues (short to ground/voltage or open circuit) in the signal path • Rare: Corroded connectors or internal Engine Control Module (PCM) failure

Powertrain (Engine & Gearbox)Standard EOBD

P0566 - Cruise Control OFF Signal Malfunction

Q: What are the symptoms of fault code P0566?

• Cruise control cannot be turned off via the switch (though brake pedal cancel usually works) • Cruise control will not engage/activate • Cruise control indicator light flashes or remains off • Check Engine Light (MIL) may be illuminated (brand specific) • Safety backup disables the speed control system entirely

Q: How do you fix fault code P0566?

STEP 1: Visually inspect the switch for physical damage or sticking buttons. Clean with electronics cleaner if necessary. STEP 2: Use a scan tool to monitor live data. Observe the 'Cruise OFF Switch' state while pressing the button to see if the PCM registers the change. STEP 3: Perform a resistance test on the switch assembly using a digital multimeter. Compare values with OEM specifications. Rotate the steering wheel during testing to identify a faulty clock spring/spiral cable. STEP 4: Inspect wiring harness for chafing or corrosion at connectors. If the switch and wiring are within spec, the fault may lie in the PCM logic or software.

Last updated:1 February 2026

Related:Rattknappar, Clock Spring, Powertrain Control Module (PCM/ECM), Kablage och kontaktdon

System

Powertrain (Engine & Gearbox)

Related Fault Codes

P0500

Vehicle Speed Sensor (VSS) 'A' Range/Performance

P0501

Vehicle Speed Sensor 'A' Range/Performance

P0502

Vehicle Speed Sensor 'A' Circuit Low Input

P0503

Vehicle Speed Sensor (VSS) Intermittent/Erratic/High

Technical Description

Diagnostic Trouble Code (DTC) P0566 is stored when the Engine Control Module (ECM/PCM) detects an implausible voltage signal from the Cruise Control 'OFF' switch. Most modern vehicles use a resistive multiplexed circuit where different buttons produce specific voltage drops. If the PCM observes a voltage that indicates the 'OFF' signal is constantly active, outside its calibrated range (high or low), or failing to communicate over the CAN bus (on newer systems), the cruise control system is disabled for safety reasons.

Possible Causes

Faulty cruise control switch/button assembly (mechanical failure or internal short)

Failed clock spring (spiral cable) behind the steering wheel causing intermittent signal loss

Wiring harness issues (short to ground/voltage or open circuit) in the signal path

Corroded connectors or internal Engine Control Module (PCM) failure

Symptoms

Cruise control cannot be turned off via the switch (though brake pedal cancel usually works)

Cruise control will not engage/activate

Cruise control indicator light flashes or remains off

Check Engine Light (MIL) may be illuminated (brand specific)

Safety backup disables the speed control system entirely

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P0566 - Cruise Control OFF Signal Malfunction

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P0566 - Cruise Control OFF Signal Malfunction

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Symptoms

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