Door ajar light flickering

I just bought a 2002 Focus ZX5 about a month ago and recently, I've been having issues with my door ajar light coming one while driving. Sometimes it will stay on for awhile and other times it will flicker on and off. I'm not sure how to go about diagnosing this one. I just pray it's not the GEM module. Any ideas?

Right rear door jamb switch was it!