Cruise Control Multi-Function Input "A" Circuit
The Powertrain Control Module (PCM) detected an abnormal voltage or resistance reading from the cruise control multi-function switch circuit 'A'. This indicates a malfunction in the electrical circuit that processes inputs from the steering wheel cruise control buttons.
This code primarily affects the cruise control system and does not typically impact the vehicle's drivability or safety. It can be diagnosed and repaired at your convenience.
Common symptoms
- Check Engine Light is illuminated
- Cruise control system is completely inoperative
- Cruise control will not set to a specific speed
- Cruise control buttons (set, resume, cancel) do not respond
- Blown fuse for the cruise control system
Likely causes
- Faulty cruise control multi-function switch (steering wheel buttons)
- Damaged or broken clock spring in the steering column
- Wiring harness issues (open, short, or high resistance) in the cruise control circuit
- Corroded or loose electrical connectors at the switch or clock spring
- Blown fuse in the cruise control circuit
- Faulty Powertrain Control Module (PCM) or Body Control Module (BCM)
What to check before replacing parts
Check the cruise control system fuses.
Look for: A blown fuse indicates a short circuit that needs to be traced before replacing the fuse.
Inspect the cruise control switch and steering column wiring.
Look for: Look for pinched, chafed, or disconnected wires, as well as corrosion in the connectors.
Test the cruise control multi-function switch using a multimeter.
Look for: Check for proper resistance values when each button is pressed according to the manufacturer's service manual; incorrect values indicate a faulty switch.
Test the steering wheel clock spring for continuity.
Look for: An open circuit or high resistance through the clock spring while turning the steering wheel indicates a failed clock spring.
Check the voltage and ground signals at the PCM or BCM connector.
Look for: If the switch and clock spring test good, missing voltage or incorrect resistance at the module indicates a wiring issue between the steering column and the computer.
This page explains the generic P0564 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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