I just took this truck to the dealer for the first real service at 201,000 miles. Oxygen sensor but they managed to rape me anyway. Now, as soon as I got home, a loud tapping sound seems to be coming from the dash, seems like it's near the speedo area. Any ideas? Can't find anything loose in dash or inside engine compartment.

it's not your flasher's/turn signal is it? the flasher unit is located behind the speedo on at least one of mine.

what year/engine?

My wife's 2003 4Runner V6 has been doing the same thing. It's driving us batty. It sounds like an electronic switch, but I can't figure out what it belongs to. I'm wondering if it is related to the ABS system...???