OBD-II Code P0566 — What It Means & How to Fix It

What Does This Error Mean?

P0566 means the PCM detected a problem with the cruise control OFF switch signal. The OFF button tells the PCM to deactivate the cruise control system completely. If the PCM receives a constant OFF signal, a stuck signal, or no signal when expected, it sets P0566. This is a minor code — it does not affect engine or safety systems — but it often means cruise control will not function properly.

Affected Models

Any 1996 and newer vehicle with PCM-controlled cruise control
Vehicles with stalk-mounted cruise control OFF/ON switches
Trucks and SUVs with separate cruise control switches on the steering column
Older vehicles with standalone cruise control modules that communicate with the PCM
High-mileage vehicles where cruise control switch contacts have worn over time

Common Causes

Cruise control OFF switch contacts have worn and no longer produce a clean signal when pressed
Switch is physically stuck in the OFF position — the mechanism is jammed and sends a constant OFF signal
Open circuit in the OFF switch wiring — PCM does not see a signal change when the button is pressed
Short circuit in the switch signal wire — the PCM reads a permanent signal regardless of switch position
Clock spring damage has disrupted the signal from a steering-wheel-mounted OFF function

How to Fix It

Test the cruise control system. Activate cruise and try pressing the OFF button. If pressing OFF does not cancel the system, the signal is not reaching the PCM. Note whether other cruise buttons (set, resume, cancel) work — this helps isolate whether the problem is one button or the whole circuit.

If cruise control cannot be turned off with the OFF button but the brake pedal still deactivates it, the brake cancel circuit is working and only the OFF button signal is affected.
Locate the cruise control OFF switch. On older vehicles it is often on the turn signal stalk or a dedicated cruise control stalk. On newer vehicles it is integrated into the steering wheel button cluster. Inspect the switch for physical damage, sticking, or contamination.

A small amount of electrical contact cleaner sprayed into the switch mechanism can sometimes revive a sticky switch contact.
Test the switch with a multimeter. Disconnect the switch connector and measure resistance across the OFF switch terminals in the pressed and unpressed positions. The reading must change clearly between states — a switch with identical readings in both positions has failed.

On multi-function stalks, the switch is often part of the stalk assembly and the entire stalk may need replacement.
Check the signal wire from the switch to the PCM for continuity and for shorts. Run a continuity test from the switch connector to the PCM connector. Also test for shorts to ground or voltage on the signal wire. Damaged wiring near the steering column flex point is common.

Steering column wiring flexes every time the steering wheel is turned. Repeated flexing eventually cracks wire insulation or breaks conductors.
Replace the faulty switch or stalk assembly if testing confirms failure. Clear the P0566 code and perform a full cruise control function test. Confirm ON, OFF, set, resume, and cancel all operate correctly.

On vehicles with multiple cruise codes (P0565, P0566, P0567 together), a clock spring or wiring harness fault is likely responsible for all of them.

When to Call a Professional

For most vehicles, this is a straightforward switch or stalk replacement. Steering-wheel-mounted button repairs involving clock spring access should go to a shop. Expect $75 to $250 for parts and labor depending on switch location and vehicle.

Frequently Asked Questions

Can P0566 cause the cruise control to stay engaged when I try to turn it off?

If the PCM is not receiving the OFF signal, it may not respond to the OFF button. However, pressing the brake pedal will always cancel cruise control because the brake switch circuit is separate from the OFF button circuit. You can also switch off the engine to cancel cruise if all else fails. This is a rare safety concern but worth addressing.

How is the cruise control OFF different from the cancel function?

Cancel temporarily pauses the set speed without turning the system off — pressing resume restores the set speed. OFF deactivates the entire cruise control system — you must press ON and then set a new speed to re-engage. P0566 affects the complete deactivation function, while separate codes relate to the cancel function.

Will P0566 cause my car to fail emissions?

Possibly — P0566 stores a fault that may prevent readiness monitors from completing, depending on the vehicle. Many states require all monitors to show ready for an emissions test. Fix the fault, clear the code, and drive normally for a few days to reset the monitors.