DTC P1564: Powertrain Control Module Detects Rapid Acceleration: Description
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
The cruise control module uses the cruise engaged circuit to request cruise control. If improper conditions are present, the PCM will disable cruise control via the cruise inhibit control circuit. During cruise control, if a sudden rate of increase in vehicle speed occurs (i.e., vehicle speed sensing problem or traveling on icy roads), the PCM will inhibit the cruise control system, and set DTC P1564.