Sure, I'm grateful. What I have discovered is this:
Problems and Their Solutions
Most often, a faulty brake light switch is to blame when the main light comes on but the speedometer remains unset. Two individual circuits make up the switch. The first one activates the brake lights, and the second one signals to the cruise control system that you aren't applying the brakes. If the second circuit doesn't work, the vehicle will assume you're braking and won't set. Verify that the brake lights are functioning properly; however, keep in mind that a faulty internal switch for the cruise control may be present even if the outside lights are operational. In most cases, you can fix the problem by replacing this cheap switch that is located above the brake pedal.
A secondary clutch pedal switch informs the engine computer if the clutch is engaged, which is only present in Sorentos with manual transmissions. The cruise control will not allow you to select a speed if this switch is malfunctioning or not properly positioned.
Problems with the "SET / COAST" or "+" / "-" rocker switches on the steering wheel could be due to loose wire ribbons or worn internal contacts; however, the master power button is functional and illuminates the dashboard.
The vehicle's computer will prevent the cruise control from engaging if the speed sensor fails to provide a consistent reading.
Suggested Following Actions
To check the brake lights, either have someone else hold the rearview mirror while you press down on the brake pedal, or go around to a reflective surface.
Connect an OBD2 scanner to your Sorento. A broken brake switch or cruise circuit can still cause the body or powertrain computer to store specific fault codes, even when the check engine light is not on.