Some time ago I posted about a total failure of gps nav and onstar. Dealer replaced gps antenna ad onstar control module. Car also equipped with dfencegps tracker installed by dealer prepurchase. We continue to have an intermittent buzzing from stereo..really intermittent. Only listen to fm stations so I don't think it's em interferrence. No rhyme or reason to pinpoint re: location of vehicle, speed, weather conditon etc. Dealer couldn't fix because couldn't reproduce buzzing. Dealer said they checked all ground connections and installations. Anyone else experience anything like this?
2016 Terrain Denali