ECM "EI80" Input Code
WARNING: This page is about a different car, the 1988 Cadillac Seville and 1988 Cadillac Eldorado. However, it is still accessible from the selected car via links, so may be relevant.
The cruise control "SET/COAST" switch display is "HI" when "ON/OFF" switch is in the "ON" position and the "SET/COAST" switch is depressed.