The speed control system in Jeep Compass and Patriot vehicles is fully electronic and controlled by the Powertrain Control Module. It operates above 25 mph and allows the driver to set and resume a target speed. The system can be disengaged manually or will disengage automatically for safety reasons like applying the brakes or shifting to first gear. To diagnose issues, technicians should check for diagnostic trouble codes, test the speedometer for flutter, and inspect components like the brake light switch.