P0591Cruise Control Multi-Function Input B Circuit Range/Performance
- Generic OBD-II code · Powertrain
- How the car detects it
- Cruise control buttons form a resistor ladder on one or two signal lines, each button giving its own voltage window. FCA uses two lines with offset windows – signal 1 is input A, signal 2 input B – and both must report the same button; GM evaluates the ratio to the reference. Any fault locks out cruise control; CARB treats this as emission-neutral, and GM and Ford set these codes without warning lamp. P0591 means signal 2 is outside its window while a button is pressed – for on/off FCA expects 0.900 V and sets the code above 0.980 V, active only while the button is held. Usual cause is oxidation at the six-pin steering wheel connector; in the Jeep Wrangler JK recalls it indicates a faulty clockspring. GM does not use P0591.
- What you may notice
- Cruise control working sporadically or not at all
- Cruise control locked out
- No check engine light
- Likely causes
- LikelyOxidised steering wheel connector at clockspring or column module
- LikelyClockspring dirty or faulty
- PossibleButton block aged
- RareColumn module or PCM
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.