The wipers are protected by a 20 Amp fuse, if this fuse is good you should have 12 volts with the ignition switch turned on at the blue wire at the wiper motor. The wiper switch bridges connections in the switch to bring power to the motor on different terminals allowing different speeds, the power goes through the motor and grounds at the motor (on some cars the wiper switch supplies ground to operate the motor at different speeds not this Toyota). I don't believe there is a relay it is all built into the wiper switch.