Drivers side frontcunder hood

What is your question?

2007 Pontiac Gran Prix has passenger side rear light that blinks sporadically fast but not in front. Dome light won't go off. Marker light operates on same bulb. Marker light works but turn signal don't. Where do I look next? Auto store suggest turning signal switch. My thought is it is in turning signal switch.

What makes this problem better or worse?

Nothing

How long has your 2007 Pontiac Grand Prix had this problem?

Month