Cruise Control Multi-Function Input "A" Circuit High
Diagnostic trouble code P0581 indicates that the powertrain control module (PCM) has detected an abnormally high electrical voltage or resistance in the cruise control multi-function input 'A' circuit. This typically means there is an open circuit or a short to voltage within the cruise control switch or its associated wiring.
This code is not a safety hazard and will not affect the vehicle's drivability. However, the cruise control system will be disabled until the issue is repaired.
Common symptoms
- Check Engine Light illuminates
- Cruise control system is completely inoperative
- Cruise control indicator light fails to turn on
- Inability to set or maintain a cruising speed
- Blown cruise control circuit fuse (in some cases)
Likely causes
- Faulty cruise control switch
- Failed or damaged steering wheel clock spring
- Open or shorted wiring in the cruise control circuit
- Corroded or damaged electrical connectors
- Blown fuse in the cruise control system
- Faulty Powertrain Control Module (PCM) (rare)
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.
Visually inspect the wiring and connectors at the steering column.
Look for: Look for frayed wires, loose connections, or corrosion that could cause high resistance or an open circuit.
Test the cruise control switch using a multimeter.
Look for: Check for proper resistance values when the buttons are pressed according to the manufacturer's service manual; out-of-spec readings indicate a bad switch.
Test the steering wheel clock spring for continuity.
Look for: An open circuit or high resistance through the clock spring indicates it has failed and needs replacement.
Measure the voltage at the PCM cruise control input pin.
Look for: If the voltage remains high regardless of switch position, but the wiring from the switch is good, suspect a wiring short to power or a PCM issue.
This page explains the generic P0581 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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