(1992) Cruise Control Disengages Itself

[Urambo Tauro]

1992 LeSabre--

Sometimes when I set my cruise-control, it will automatically dis-engage after just a few minutes. (The green "cruise" light on the dash stays lit.)
I try to set it again, and it cuts off even sooner (after a few seconds). It seems that if I leave it turned off for a long period of time, say- a couple weeks- it will work longer before it gives up.

I'm not familiar with these, but I've heard they operate off a vacuum system. This makes sense considering the symptoms; I'm thinking there's a leak.

Where do they put the module/hoses on these? (Do I have to remove something to get there?)
Where exactly should I be looking and what should I be looking for? Is there maybe a common place these will tend to leak?

[Bassasasin]

A common leak is at the brake pedal.. the brake valve leaks. Its used to disengage the Cruise.

Of course there are other possibilities. Servo assist valves getting dirty inside.
My 94' turned out to be the PCM itself giving exastly the same symptoms.

Good Luck