Possible Causes

WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

Short to ground in circuits 682 (DB), 680 (LB/OG), 684 (PK/YE) or 671 (LB).
Open in circuit 1302 (WH/LG).
Inoperative front wiper motor.
Inoperative multifunction switch.