Team -

I had a mysterious rattle in my dash that I isolated to the passenger side speaker grill (cover). Although it is largely a cold weather symptom. I noticed the rattle when riding over rough pavement, expansion joints et al. After much probing, I noticed that the grill construction can allow play and noise as a result. I removed the A pillar garnish and the popped off the speaker cover. I then used adhesive, thin-strip foam tape on the contact areas and where the grill nearly meets the windshield. Problem fixed. Just thought I'd throw it out there if others have random noise that remains undiagnosed. It's worth a try.