You have two power leads to a Pioneer radio. A red one (power from the ignition switch) and a yellow one (constant 12V power). One of these may have an in-line fuse that has blown. Try and follow the wires and see if there is one present. Pioneer also uses a 10A fuse which is adjacent to the power plug on the back of the radio. Additionally there is a black ground wire which you should confirm is still attached to a ground point. Or the problem might be with the switch you use to switch from "travel" to "park". I'd verify whichever is easiest first. Probably have to pull the radio to confirm the 10A fuse.
