Cruise control

The brake switch & some models Separate Cruise switch both at pedal seems likely to be out of adjustment or loose electrical connections or bad or shorting as the switch itself may be malfunctioning in-witch it could turn off when you move it for blinker ect, if its a manual trans also could be a switch for it. Check if the brake lights are working when the cruise control is not functioning. If cruise control & brake lights fail at the same time I would suspect a faulty brake switch (may have to have someone follow you with phone/CB in hand). There is no vacuum on fuel injected I am aware of. Although there is sensors tied to this it is connected to other sensors for trans I think it is the torque converter sensor, Could be loose/bad wiring and should turn check engine light on and you do not say you have a check engine light on so I would think the sensors and their wiring is fine and turn my attention to other reasons/causes.

Would it read a code?