Cruise Control Multi-Function Input "A" Circuit Diagnostic Trouble Code (DTC): P0564

P0564 code definition

The P0564 code means that the powertrain control module (PCM) has identified an electrical fault in the cruise control multi-function input circuit.

What the P0564 code means

The P0564 code is a generic OBD-II code that occurs when the PCM perceives that the vehicle's speed is unable to be controlled. It will cue a self-test of the cruise control system, and create this code if the test finds that there is irregular voltage resistance in the cruise control's multi-function input circuit.

What causes the P0564 code?

There can be several reasons for this code, including:

• The most common reason is a failed cruise control switch
• There may be some open or shorted circuitry within the cruise control buttons/controls (often due to fluids spilled on cruise control components)
• There can be electrical issues relating to shorten or exposed wiring, corroded connectors, and blown fuses

What are the symptoms of the P0564 code?

The P0564 code is often recorded in vehicles in which the cruise control is no longer allows the operator to set the vehicle's speed controls. There may also be a check engine indicator, and blown fuses are often a sign of a problem.

How does a mechanic diagnose the P0564 code?

P0564 is diagnosed with an OBD-II scanner, and it will be necessary to look through the freeze frame data to see when the code appeared. The mechanic should then reset the fault codes and do a road test to see if the system works and/or the code reappears.

If so, then the mechanic needs to perform a visual inspection on all of the related electrical components, including connectors, wires and straps. Anything in need of repair or replacement must be addressed, and the system retested. If the code still appears, it will require the switch to be replaced.

Common mistakes when diagnosing the P0564 code

One of the key mistakes made during diagnosis and repairs for P0564, or related codes, is the failure on the part of the technician to check for blown fuses after the replacement of any components. It is not unusual for different components in the system to be replaced, wrongly, when the only repair needed after the initial component replacement was to replace fuses.

How serious is the P0564 code?

Although the P0564 code will not prevent the car from operating safely and effectively, it can be the sign of a more serious issue. This is because one of the symptoms of this issue is blown fuses, which can be a sign of a much more severe electrical problem.

What repairs can fix the P0564 code?

To overcome the P0564 code, the following steps are needed:

• The mechanic must test the vehicle with the scanner, reset fault codes and do a road test to verify that the P0564 code reappears.
• They must then do a full inspection of the related electrical connections to be sure they are in working order, without any damaged, corroded, shorted or disconnected components or wires. Any issues uncovered must be repaired and the system retested. If there is still a code, the issue is likely a faulty cruise control switch.
• Replace the switch and do a test drive to see if it is operable. Whether it is operable or not, retest for the code. If the system does not operate and the code persists, the vehicle must be lifted and another test run while the vehicle is held at 25mph. The cruise control's electrical connector must be disconnected while the vehicle is operating and tested for voltage. If it meets manufacturer specs, disconnect the PCM and cruise control module to test the circuitry between the switches.
• If there is still a code, you will need to do a resistance test on the cruise control power switch and buttons, as this is the final reason why the code will appear.

Additional comments for consideration regarding the P0564 code

When testing the circuit resistance, leave the cruise control module and PCM disconnected, and replace any switches as needed.

Need help with a P0564 code?

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