2002 rear wiper/sprayer problems

I have a 2002 Mountaineer. Starting yesterday every time I start the vehicle the rear wiper sprayer kicks on and the wiper starts running even though the switch is in the off position. The sprayer runs about 10 seconds and then stops, however the blade continues to run about once evey two second. The switch is set to off. I can turn the switch to on but when I turn it back off the sprayer kicks right back on. I have looked through the manual hoping to find a rear wiper relay but to no avail. Nothing in the manual mentions a wiper relay, only fuses which I have replaced. If anyone has any idea about this please contact me.

Thanks,

Dwightd1