I think you'll find that the right rear ring magnet is damaged, which is attached to the wheel bearing. From the mechanic who replaced mine, "GM put in a real cheesy part when they designed the Acadia". Cost $500.00 for replacement and labor, hear in Michigan. Bad part is all 4 wheels has the same part that could go bad. Forgot had the exact same symptoms clicking noise when I started out and then would away, brakes felt like they were pulsating, and sounded like I was dragging a tree limb.