How do I change the bulb on a 2001 LHS High mount brake light? Also if it is not the bulb how do I troubleshoot?

 

I figured it out yesterday. You have to access it through the trunk. There are three snaps to undo (I used a pair of needle nose pliers) and there are two bulbs to change (# 921). Twist each harness counter clockwise and I found both bulbs were burned out. Not to hard at all.