P0578 Buick Cruise Control Multi-Function Input A Circuit Stuck

P0579 Buick Speed Control Switch 1 Performance Condition

Possible causes
– Faulty Cruise Control Function Switch
– Cruise Control Function Switch harness is open or shorted
– Cruise Control Function Switch circuit poor electrical connection
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
– Cruise control system inoperative
Buick Vehicle:Buick Regal – ?Buick Riviera – ?Buick LaCrosse – ?David Dunbar Buick – Buick Century – Buick LaCrosse – Buick LeSabre – Buick Lucerne – Buick Park Avenue – Buick Regal – Buick Verano – Buick Enclave – Buick Encore – Buick Rainier – Buick Rendezvous – Buick Terraza – Buick Riviera