Cruise Control Multi-Function Input A Circuit Range/Performance
What it means
P0579 means the cruise-control multi-function switch "A" circuit is reading outside its normal range — the switch input is higher or lower than expected. This typically makes cruise control unresponsive or erratic. It has no effect on how the engine starts or runs.
Can I keep driving? Safe to drive — the fault only disables or disrupts cruise control; starting and engine performance are unaffected.
Real-world scan data
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Cruise control inoperative or erratic
- Cruise-control buttons unresponsive
- Cruise-control or check-engine warning light on
Common causes
Most likely first
- Faulty cruise-control multi-function switchLikely
- Damaged wiring or connectors in the switch circuitCommon
- Loose or corroded electrical connectionsCommon
- Failed cruise-control module or ECM (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and note the conditions when it set.
- Measure the switch's resistance/voltage against spec across each button position.
- Inspect and repair wiring and connectors in the switch circuit.
- Replace the switch if its signal reads out of range.
- Replace the module only if the wiring and switch check good.
FAQ
Quick answers
Is it safe to drive with P0579?+
Can I just clear P0579?+
Related codes
Read & clear P0579 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.