blower motor and wiper problem for the wiring gurus

hi
i have a 99 jimmy 4.3l
anyway the problem i'm having is
the blower wouldn't come on unless you turned on the wipers.
then the blower would turn on.
the other day it was raining and the wipers stopped and so did the blower for the defrost.
i have changed the pulse board and the wiper motor.
someonetold me it was maybe in the multifunction switch
but everything else works the turnsignals,crusie, and even the washer
but the wipers wont start.
i checked all the fuses also everything looks good.
any ideas would be greatly apprecited
thanks
Don