99 T&C cruise control kick-down

Does anyone know if there is a specific "kick-down switch" for the tranny when going up steep grades or even minor grades? The reason I'm asking is because when I'm driving with the cruise on when going up hills, of any grade, I loose approximately 15 MPH before the tranny will kick down to maintain speed. Sometimes I tap the accelerator to manually kick down the tranny but it doesn't normally last very long. I own the typical maintenance manual, ie. Chilton's, but it doesn't have really any specifics about the electrical components of the tranny. Any help would be greatly appreciated. Thanks everyone, in advance.