Cruise Control Inhibited

WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

The powertrain control module (PCM) inhibits the cruise control operation when any of the following conditions exist:

A cruise control system DTC has been set.
The vehicle speed is less than 40.2 km/h (25 mph).
The vehicle speed is too high.
The vehicle is in PARK, REVERSE, NEUTRAL, or 1st gear.
The engine RPM is low.
The engine RPM is high.
The system voltage is not between 9 volts and 16 volts.
The anti-lock brake system/traction control system is active for more than 2 seconds.