P0579Cruise Control Multi-Function Input A Circuit Range/Performance
- Generic OBD-II code · Powertrain
- How the car detects it
- Cruise control buttons are almost always a resistor ladder on one or two signal lines, each button giving its own voltage; the module reading it (GM and Saab from about 2010: the body module; FCA: steering column module or PCM) sends the button state to the engine module over CAN. CARB names cruise control as the example of an emission-neutral diagnosis – it is simply switched off – so GM lists all these codes as type C and Ford as non-MIL: no warning lamp, the engine runs normally. FCA uses two redundant lines with mirrored ladders: P0579 sets when signal 1 is outside its window while a button is pressed – for on/off it must lie between 0.235 and 0.353 V – and is active only while the button is held. Usual cause is oxidation at the six-pin steering wheel connector or the clockspring; the Jeep JK recall replaces the clockspring.
- What you may notice
- Cruise control cannot be switched on at times
- Cruise control locked out
- No check engine light, engine runs normally
- Likely causes
- LikelyOxidised or dirty contacts at the steering wheel connector
- PossibleSwitch contact for signal 1 not closing
- PossibleClockspring faulty
- RareWiring or module
- Repair
- Medium · Often possible to do yourself.Typical cost: €0 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.