Cruise control not working, 2.5 automatic

My Cruize control hasn't worked since 60,000 miles. Car now has 94,000 miles on it. Actually, the cruize would work sometimes but not others. Now not at all. If I turn the cruize control on, it simply automatically turns itself off shortly after, regardless if I try to set a speed or not.
There is plenty of vacumm to the servo unit. I am wondering if the output speed sensor needs to be replaced or cleaned. However, speedometer, shifting, odometer and such function perfectly & always have.
Any ideas on what the problem may be?

On my 95 Sebring the brake light switch malfunctioned. The brake lights
would still work intermittantly. My cruise control acted the sme way. When I replace the switch, the cruise resumed working. Hope this helps.

Which switch did you replace? You don't mean that replacing the brake light switch fixed the cruise control, do you?

The brake light switch (on the pedal) is actually 3 switches in one. One switch is for the brake light and the other 2 for cruise control.