Error Code P0564 is defined as Cruise Control Multi-Function Input “A” Circuit. This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II system, especially those vehicles made since 1996 up to present. It commonly applies but not limited to Alfa Romeo, Chevrolet, Chrysler, Dodge, Ford, Land Rover, Mazda, and Nissan. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.
The job of Cruise Control is to maintain a vehicle speed set by the operator manually (through steering wheel buttons, multifunction such as wipers, signal light, cruise, etc.) switch mounted to the right of the steering column. With this feature, the driver no longer has to control the speed of the vehicle through the gas pedal, and for vehicles with automatic (A/T) transmission, it can also adjust shift points according to the demands for real-time driving conditions.
Generally speaking, this error code refers to the multifunction switch on the steering column. With that said, location varies between manufacturers, so it’s important to consider this factor. To narrow the location, the cruise control button would be the good start. The error code refers to a specific input circuit within the cruise control system. To find out which circuit and wire to focus on, it’s best to refer to the service manual. The letter in the definition of the code determines the wire or circuit you must diagnose and repair. The latter “A” could be distinguished for the connector, circuit group, wire, etc.
Error Code P0564 which refers to Fault in the Cruise Control Multi-Function Input “A” Circuit, means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) determines that the vehicle’s speed cannot be controlled. At first, PCM will cue a self-test for the cruise control system, and if it finds out there is irregular voltage resistance in the cruise control’s multi-function input circuit, then it will register this code.
Other related error codes include:
- Error Code P0578
- Error Code P0579
- Error Code P0580
- Error Code P0581
As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory system. Other common symptoms include:
- Abnormal vehicle speed when the Cruise Control is activated
- Inoperative Cruise Control
- Cruise Control light activated, regardless of switch position
- Cannot set Cruise Control at the desired speed
The most common cause for this code is failed Cruise Control switch, such as broken, missing, or stuck switch. Other possible causes include:
- Open or short in the circuitry of Cruise Control buttons/controls (often caused by fluid spilled on cruise control components)
- Electrical issues such as blown fuses, corroded connectors, exposed or shorted wires
- Connector malfunction caused by broken plastic tabs, corroded pins, swollen connector body, etc.
- Dirt, fluid, and grime in cruise control buttons/switch affecting its mechanical operation
- An issue in the PCM (water intrusion, internal short, overheating, etc.)
How to Check
Locate the multi-function or cruise control switch off your vehicle, then check for signs of contamination in the plastic buttons, switches, etc. These components can get dirty and greasy, which can lead to malfunction or abnormal operation. Make sure the mechanical operation is seamless and smooth. Any problems must be addressed immediately. If your scan tool or OBD reader has this function, then observe the electronic operation of the switch through the Data Stream to observe real-time data.
Tip: Make sure you don’t spray any cleaning solutions directly to the button. Simply dampen a clean rag lightly with either water, soap and water mixture, dash cleaner, etc., and then carefully remove the debris from the crevices of the switch. You can also use an air powered blow fun to help you remove debris without causing further damage.
Next access the connectors and harness connected to the cruise control/multi-function switch input circuit. You may have to remove dash plastic or shrouds. Be careful in removing these components. Comfortable room temperature helps in working with the dash or interior plastic.
If you can access the connector, then apply the specific troubleshooting steps provided in the service manual. Switch test will most likely include recording electrical values with your multimeter. This may also include operating the switch while recording and static testing. Again, refer to the service manual for the specific “diagnostic flow chart” for the particular make and model of the vehicle.
Problem with the PCM is usually the last resort for diagnosis. And since it’s the most expensive electronic part, it’s best to leave it to the professionals.
How to Fix
Depending on the diagnosis, common repairs for this code include:
- Repair or replacement of damaged electrical connections (i.e. corroded wires, damaged cables, disconnected or shorted components or wires)
- Replacement of cruise control switch
Though this code will not prevent you from driving the vehicle safely, it can be a sign of a more serious underlying problem, as one of its common symptoms is a blown fuse, which is a sign of serious electrical damage.