The speed control for your Dakota is governed directly and solely by the PCM -- there is no separate fuse for the system. The switches on your steering wheel communicate with the PCM via the clock spring and duplexed wires (all the signals go through one signal wire and one sensor ground wire). The PCM controls the selected speed using the throttle position actuator in your electronic throttle body.
If the system turns itself off, or does not turn on, it's either the PCM or the wires running from the switches to the PCM, through the clock spring in the steering wheel. I suspect the latter, but you would need to have someone with the appropriate equipment check for signals and switch function.
If you're going to work on the clock spring, please be sure to disconnect the battery, and wait for a time for the capacitors in the air bag system to discharge. You don't want the one in the steering wheel going off in your face!
