What it means
The ECU detects an implausible state of the cruise control on/off signal - either the master switch is stuck on, intermittent, or shows a logic level that does not match other dash signals.
At a glance
- Usually lights the check-engine light
How it works
The cruise-control master switch sends an on/off signal that tells the control module whether cruise control is enabled. P0565 sets when the module sees an implausible on-signal state, such as a stuck or intermittent switch signal or one that conflicts with other dash inputs.
Common causes
Most likely first.
- Cruise control on/off switch stuck or failed
- Short or open in switch wiring
- Loose or corroded connector
- Fault in the related control module
Symptoms
- Cruise control may not engage or may not switch off as expected
- Cruise control may operate intermittently
- Check-engine light may come on
How to diagnose it
- Review freeze-frame data and related cruise-control codes to determine when the on-signal became implausible.
- Watch the cruise-control on/off status in scan-tool live data while toggling the master switch and confirm that it changes cleanly between states.
- Inspect the master switch or stalk and its connector for sticking, looseness, corrosion, or damaged wiring.
- Test the switch contacts and on-signal wiring for an open, short, or intermittent connection while operating the switch.
- If the switch and wiring respond correctly, check related module inputs and grounds using the manufacturer's diagnostic procedure.
Common fixes
- Free or clean a sticking master switch if it can be serviced.
- Repair loose, corroded, open, or shorted wiring at the cruise-control on-signal circuit.
- Replace a failed cruise-control on/off switch or stalk.
- Repair the related control module or its connections if testing identifies a module-side fault.
Can I keep driving?
Avoid using cruise control until the on/off signal works reliably. If cruise control will not switch off as expected, cancel it with the brake and turn the system off; stop safely if it 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.