Battled this for years, replaced brake switch even though no brake light issues. That solved it for about 2 years. Now back to "engage CC, light illuminates on cluster, hit set, CC turns off." Code P0579=master switch, wiring, clock spring. I don't want to throw parts at it. Any suggestions, testing, etc?

 

Test the switches in the steering wheel.

 

3 wire switch. 1 on/off and one set button. I believe I'm testing it correctly. Center wire black. Have continuity on. Set button momentarily continuity.

 

I believe the switches just modify a voltage..... so, testing resistance across the wires when you press various buttons. Don't know what the values are supposed to be though... Need a service manual for that. (and problem proper testing method as well.... unless a high-zoot scanner can tell you which button is being pushed.)