I purchased my vehicle used from a Lexus Dealership with 42k miles on it. At apprx 45K miles I purchased an extended warranty to 100k. After owning it 6 mo, the entire navigation & radio system went completely out. This includes the sound to your blinkers, alert system, etc as they all use your radio system/speakers. The GMC Dealership filed a claim under my Warranty for the Nav/radio system and it was replaced free of charge (except my $75 warranty co-pay).

Note: my battery was drained after driving it around for a few days in this state. This became important later when this happened for a second time in a different reporting; possible electrical system "on" and not shutting off draining the battery. I replaced the battery with a new one since it was 3.4 years old and out of warranty.