Cruise Control: Notes
CAUTION:
Do not use the cruise control when driving in heavy or varying traffic, or on slippery (rainy, icy, or snow covered) or winding roads.
Your cruising speed can be maintained up or down grades within the limits of engine performance, although a slight speed change may occur when driving up or down the grades. On steeper hills, a greater speed change will occur so it is better to drive without the cruise control. See Fig 1.