Defogger Relay
WARNING: This page is about a different car, the 2002 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
Turn ignition off. Remove defogger relay from driver side junction block. Check continuity between terminals No. 2 and 5. See Fig 1. Continuity should exist. Using jumper wires, apply battery voltage between terminals No. 2 and 5. Continuity should exist between terminals No. 1 and 3. See Fig 1. Replace relay if continuity is not as specified.