I have a 1998 F-150, AFTER TURNING THE LIGHTS ON THE backlighting for Instrument Panel, Door buttons and Climate control go off after about 20 mis, everytime? is there a relay in the GEM that is heating up and shutting down? or just going bad?

 

If this is happening while driving, it sounds like the GEM/LCM has lost a power feed and it thinks the engine is off, so it's saving your battery.

If it's happening with the engine off, it sounds normal.