This error has only occurred once but was very distracting.
As I was driving home from work one afternoon in June 2008 I noticed the green cruise control lamp on the instrument bezel of my 2000 Chevrolet 2500 4x4 Silverado pickup truck was blinking on and off at regular approximate one-second intervals.
The cruise control was turned off.
I turned the cruise control switch on the turn signal stalk on and off several times, and the cruise continued to blink on and off.
This blinking continued until I returned home and turned off the ignition.
Neither the cruise control lamp nor other indicator lamps have indicated any problem, before or since the blinking cruise control lamp incident.
There have been no malfunctions on the truck of which I am aware.
I am not going to spend any money on diagnostics unless I am aware of a problem which I deem to be important.
I do not possess an electronic diagnostics code analyzer.
Is there some documented problem that causes a cruise control lamp on a Silverado to blink on and off, even with the cruise control disengaged and turned off?

You might have your dealer check for any tsb's on the problem.
or get a All data sub on it.
http://www.alldata.com/products/diy/index.html

Usually feed back on dask lights is caused by bad ground or bulb or socket in tail /turn signal light circuit.

But the blinking is strange deal.

If just one time and everything is still working good.
You may just have to wait and see if it does it again.
If so also wiggle turn signal and light switch and cruise switch and turn off tail lights and see if it changes.
Good Luck
MT