in my friends car, the head unit works fine, but all four of the speakers short out when we hit a bump, they go off, and we gotta hit another bump it seems in the right spot, then all four will go on. we figure that they are shorting, but all four at once? we're clueless
If just head unit and speakers...possible the head unit is messing up, loose or installed incorrectly. If amp present....amp is shorting and/or installed correctly. Start tracing wires.