P0591: Cruise Control Multi-Function Input B Circuit Range/Performance
What to do
Driveable; cruise control may respond unpredictably or not at all. Ask whether the contacts were cleaned before a new switch pack is ordered.
What this code means
The second cruise control input produces values within range but matching no defined button — the counterpart of P0579. Contact corrosion drifting the resistance ladder is the usual cause, and cleaning the contacts is worth trying before the switch pack is replaced.
Likely causes
Start here
- Corroded switch contacts · easy
- Faulty cruise control switch · moderate
Less common
- Water ingress into connector · easy
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
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