First off, does the cruise light on the switch illuminate when you turn
the switch "on"?  Does it remain lit while you drive and attempt to set
the cruise speed with the steering wheel "set" button?  Or does it
begin to flash, and what event(s) cause it to flash?

Things to check if cruise indicator light works as it is supposed to:
*Power to the cruise actuator under the hood.
*This system has a cruise vacuum pump / solenoid assembly - get a
wiring diagram - temporarily run B+ to the B+ terminal, and ground the
other three wires to see if the pump, hold, and vent functions operate.
*Make sure the actuator moves when you power the pump and the hold
solenoid, and retracts when you either remove all power -or- ground the
vent solenoid input.
*The cruise switch has two wires going to the cruise computer.  B+ on
the first wire occurs when pressing "set/coast".  B+ on the second wire
is "resume/accelerate".  B+ on both at the same time is "cancel".  This
switch can go bad.  Make sure the "set/coast" input works and the
"cancel" signal isn't stuck on.
*The brake switch can fail or be out of adjustment and cause no cruise
(telling computer that you are braking when you aren't)
*I believe there is a park/neutral input from the automatic trans; if
you have a manual trans then there is a clutch cancel switch on the
pedal braket that can fail much like the brake switch.

Toyota MDT in MO