Cruise Control Inhibited

WARNING: This page is about a different car, the 2017 GMC Acadia. However, it is still accessible from the selected car via links, so may be relevant.

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

The ECM has not detected a brake pedal activation from the body control module (BCM) this ignition cycle.
A Cruise Control System DTC has been set.
The vehicle speed is less than 38.6 km/h (24 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 Antilock Brake System (ABS)/Traction Control System (TCS) is active for more than 0.5 seconds.