P0578Cruise Control Multi-Function Input A Circuit Stuck
- 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. P0578 means input A shows the same valid button voltage beyond a time limit – a button stuck. The principle matches GM's per-button codes (20 s or 89 s), here for the whole line A. No manufacturer document available to us uses this code. FCA's Jeep JK recall for the clockspring lists its own code P1593 for a stuck switch instead.
- What you may notice
- Cruise control reacting unexpectedly
- Cruise control locked out
- No check engine light, engine runs normally
- Likely causes
- LikelyButton mechanically stuck
- PossibleMoisture or dirt producing a constant value
- RareClockspring or connector
- Repair
- Medium · Often possible to do yourself.Typical cost: €40 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.