What does the "A" mean? Is there a B?

The letter identifies the switch assembly, not the button. Most vehicles have only one set of cruise controls, so only "A" exists on them. Designs that carry a second independent set — either a redundant channel used to verify the first, or a separate group of buttons elsewhere on the wheel — report that one as "B". If your vehicle only has one cruise switch group, you will never see the B code and there is nothing missing.

Why did all my cruise buttons stop working at once?

Almost certainly because they all share one wire. Most cruise switch assemblies are built as a resistor ladder: every button feeds the same signal circuit and is identified by the resistance it adds, rather than having a wire of its own. That keeps the number of conductors passing through the steering column small, but it means a single open anywhere in that shared wire takes out every function simultaneously. The fault looks like a module failure and is usually a connector or a cracked clockspring ribbon.

Can a faulty switch make the car do the wrong thing rather than nothing?

Yes, and this is a signature of the ladder design. The module does not know which button you pressed — it knows what voltage appeared on the wire and looks that value up in a table. If corrosion or a drifted resistor shifts the value onto a neighbouring step, the module decodes a different command perfectly confidently. That is why some vehicles with this code accelerate when Resume is tapped, or cancel the moment cruise is set. It also means the fix is the switch assembly, not the module that obeyed it.

Is it safe to drive with this code stored?

Driving is fine. Cruise control is a convenience system and the engine will run normally without it. The one thing worth being careful about is the middle failure mode described above, where a degraded switch produces the wrong command rather than no command. If your cruise control is doing something unexpected rather than simply not working, switch the system off at the main control until it is repaired instead of continuing to use it and hoping.

OBD-II trouble code

P0564: Cruise Control Multi-Function Input "A" Circuit

The module could not make sense of the voltage arriving from the cruise control switch assembly. On most vehicles every button on that stalk shares one wire and is identified purely by resistance, which is why one fault can kill all of them — or make the module read the wrong button entirely.

Low severityPowertrainCruise ControlDrivable short-term

Quick facts

System: Powertrain
Category: Cruise Control
Severity: Low severity
Drivable: Usually safe to drive short-term
Repair cost range: $0 – $700
DIY difficulty: Intermediate DIY

What does P0564 mean?

P0564 is the parent code for the cruise control switch assembly, and the letter "A" identifies which assembly rather than which button. Vehicles with a single set of cruise controls only ever have an "A"; some designs carry a second, independent set — a redundant channel used to cross-check the first, or a second switch group on the opposite side of the wheel — and those appear as "B". The code is the module reporting that the input arriving from assembly A did not correspond to any command it recognises.

Understanding the wiring is what makes the rest of this straightforward, and it is where most people go wrong. It would seem natural for six cruise buttons to have six wires. Almost none of them do. Running six circuits up a steering column and through a clockspring is expensive and fragile, so manufacturers overwhelmingly use a resistor ladder instead: all the buttons share a single signal wire, and each one places a different resistance value into that circuit when pressed. The module holds the wire at a reference voltage through an internal pull-up and simply reads how far the voltage drops. One value means Set, another means Resume, another means Cancel, and so on down the ladder.

That design decision explains the symptoms this code produces, and they are not the symptoms people expect. Because everything shares a wire, a single open in that wire disables every cruise function simultaneously — the driver reports that cruise control is completely dead, which sounds like a module or a fuse rather than a switch. And because identification depends on a resistance value rather than on a dedicated wire, a corroded contact or a drifted resistor does not merely fail to register: it can produce a voltage that the module correctly decodes as a different button. That is why a vehicle can accelerate when you press Resume, or refuse to set because the module keeps receiving a Cancel it was never sent.

The practical consequence is that testing here is not continuity testing. Continuity tells you whether a path exists; on a ladder circuit the path always exists, and what matters is the precise value it carries. The correct test is to backprobe the single signal wire, press each button in turn, and compare the voltage against the manufacturer's table. A button that lands on the wrong step of the ladder is a definitive answer, and it is an answer no amount of wiggling and buzzing wires will ever produce.

The last thing to know is where the circuit physically lives. If the switches are on the steering wheel, the signal passes through the clockspring — the flat ribbon that maintains an electrical connection to a part that rotates. Clocksprings crack, and when they do the fault depends on steering angle, so it will not reproduce on a stationary vehicle with the wheel straight. If the switches are on a column stalk instead, the clockspring is not involved and the connector at the base of the column becomes the more likely suspect.

Common causes

Worn or contaminated contacts inside the multi-function switch assembly producing an out-of-range resistance
Liquid spilled into a steering wheel switch pad, leaving conductive residue that shifts several ladder values at once
Cracked clockspring ribbon interrupting the shared signal wire at particular steering angles
Corroded connector at the base of the steering column or behind the switch pad
Open in the single shared signal wire, disabling every cruise function at once
Short to ground on the signal circuit, holding the module at a permanent false button press
Drifted resistor value inside the switch assembly, causing one button to be decoded as another
Body control module fault or missing configuration after a module replacement

Symptoms

Cruise control completely inoperative, with no response from any button
Cruise indicator on the dash failing to illuminate when the system is switched on
Pressing one cruise button producing the action of a different one
Cruise engaging and then cancelling itself without driver input
Function returning intermittently, often related to steering wheel position
Several cruise-related codes stored together rather than one
Steering wheel controls for other functions, such as audio, also behaving oddly
Check engine light with no driveability complaint of any kind

Diagnostic steps

1.Find out first whether your switch assembly is a resistor ladder or a set of discrete wires. Count the wires at the switch connector. Two or three wires serving five or six buttons means a ladder, and everything below applies. One wire per button means the circuit is discrete and a single-button complaint is genuinely a single-button fault.
2.Get the voltage table for your specific vehicle before probing. On a ladder circuit the only useful test is comparing measured voltage against the value the manufacturer expects for each button, and those values differ between makes and even between trim levels. Without the table you are reading numbers with nothing to compare them to.
3.Backprobe the signal wire at the switch connector, key on, and press each button in turn while watching the meter. You are looking for two things: a button that produces no change at all, and a button that produces a voltage belonging to a different button. The second is the more revealing result, because it tells you a resistor has drifted rather than a contact having failed.
4.Check the rest voltage with no button pressed. It should sit at the module's pull-up value. If it rests part way down, something in the assembly is partially shorted and the module is permanently seeing a weak button press — that is often the whole fault, and it explains why the system may refuse to arm at all.
5.Work the clockspring if the switches are on the steering wheel. Rotate the wheel lock to lock with the meter connected and the assembly at rest, watching for the reading jumping. Clockspring ribbon cracks show up as position-dependent faults and they will never reproduce with the wheel sitting straight in a workshop.
6.Inspect the switch pad for liquid ingress before ordering anything. Steering wheel switch pads sit directly beneath everything a driver spills, and the residue is conductive while damp and corrosive once dry. A pad that has taken a drink will read wrong on several buttons at once, which mimics a wiring fault exactly.

Repair cost

$0 – $700

The floor is zero because a connector that was not fully seated after steering wheel or column work is a real share of these and costs nothing to correct. Diagnosis is $80 to $150 and needs the manufacturer's voltage table to be worth anything. A steering wheel switch pad is $30 to $250 in parts with half an hour to an hour of labour, and on vehicles where the pad is bonded into a larger trim assembly the part price climbs sharply. A column-mounted multi-function stalk is $60 to $350 fitted. A clockspring is $150 to $450 including labour, and that job involves removing the driver airbag, so it is the point where this stops being a reasonable driveway repair.

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Open the Repair Cost Estimator with cruise control switch / stalk replacement preselected. Adjust labor rate and vehicle category to fit your situation.

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DIY vs shop

This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.