On my 98 Corolla, 2001 Camry and now my 2005 4cyl auto Camry, I have had a very annoying buzzing sound especially when it gets cold out, that I thought was coming from the dash on the 98 and 01. It sounds like a spring rattling on a glass plate. On my 05 I discovered the genral origin and am taking it in for diagnosis and repair next week. I thought it might be the spring that keeps the shift lock button out rattling inside, but it turns out it is the chrome trim piece on the shaft of the shifter. All of my mentioned cars had this trim and I can pretty much assume that that's what the rattle was in those cars. As I'm driving over a bumpy surface, I hold the trim shroud and no rattle. I can tap the shifter and make it rattle, but if I hold the trim piece, no rattle. Just a poor design that I unfortunately had 3 generations of Toyota that had it. Thought I would pass this along since I had it on 3 Toyotas, others probably have it as well. It decievingly sounds like it is coming from the dash and is present mostly in sub 30f weather.
Reb