Honestly I don't have an idea what the problem could be. I know what a pain in the butt these intermittent problems can be. I had a 2005 Raineer that had an intermittent problem with the blinkers. I would flick the blinkers on every time I passed a Buick dealer to see if I could get it to replicate...never did it near a Buick dealer, eventually the lease term came due, I turned it back over to GMAC and that solved the problem. 