P0579 Cruise Control Multi Function Input A Circuit Range Performance

Definition: The OBD2 code P0579 indicates a problem with the cruise control system, specifically related to the multi-function input “A” circuit. This code is triggered when the Engine Control Module (ECM) detects that the actual signal from the cruise control switch does not match the expected range of operation.

P0579: Cruise control multi-function input A circuit range/performance
Severity: Moderate

Common Causes

P0579 – Cruise Control Multi-Function Input A Circuit Range/Performance

Common causes:

• Faulty cruise control switch
• Open or short circuit in the cruise control wiring
• Defective cruise control module
• Issues with the vehicle’s ECM/PCM

 

Common Misdiagnosis

OBD2 Code: P0579

Description: Cruise Control Multi-Function Input A Circuit Range/Performance

Common Misdiagnosis: Replacing the cruise control switch without checking for wiring issues or a faulty brake light switch.

 

Common Diagnostic Steps

OBD2 Code: P0579

Description: Cruise Control Multi-Function Input A Circuit Range/Performance

• Check for any additional codes that may be present and address them first.
• Inspect the cruise control switch for proper operation and signs of damage or wear.
• Examine the wiring and connectors related to the cruise control system for corrosion, damage, or loose connections.
• Test the voltage and ground signals at the cruise control switch using a multimeter to ensure they are within specifications.
• Verify that the brake pedal position sensor is functioning correctly, as it can affect cruise control operation.
• If equipped, check the clock spring in the steering column for continuity issues that might affect signal transmission from the steering wheel controls.
• Consult vehicle-specific repair manuals or technical service bulletins (TSBs) for known issues related to this code on your specific make and model.
• If all components test okay, consider reprogramming or replacing the engine control module (ECM) if recommended by manufacturer guidelines.