i'm willing to bet it's coming from your controller unit (aluminum block where all the lines meet, under the coolant expansion tank).
w/out looking at it of course ;p
i really hope it's not that though, trust me i had to drive 2 miles on hilly roads with just manual switching and using ebrake and to change it you have to pull out driver's headlight, a pita to change since space is limited and unlike every other car on the road the placement of it is horrible...
did i mention they run for 2k from dealer, about $600 from junk yards?