Trunk light censor

There is likely a switch in the trunk latch assembly, try pushing down and pulling up on the trunk and see if the light flickers on and off. This could also be from the wiring going to the trunk switch.

The switch is in the trunk latch, there is a green and black wire at the trunk latch that has continuity to ground with the trunk open and with the trunk closed continuity to ground goes away (turning off the "trunk open" light on the dash board display).