The seat belt light comes on intermittently; this is an idiot light that is turned off by pushing the button under the seat belt light.

The seat belt light/button was a passive way GM employed to get you to wear your seat belts.  The light on "The Toy" lights up every time I turn the ignition on and I push the button to turn it off.  To the best of my knowledge it is not wired into anything else.

Pushing the button switches a normally closed switch to open, turning off the light.  When power is removed, the switch reverts to its' normally closed position.  If it periodically comes on, but goes off again when you push the button, there is an intermittent open in the power tot the switch.  It is probably harmless but annoying.  Check connections, and wiggle wires to see if one is broken inside.  Does anything else flicker when the light comes back on?  If not, there is a pretty short circuit that could be the problem.  If other things flicker, the intermittent open is before them in the circuit.

Larry