BIG BABY

Both do not work.The trunk light comes on and stays on
when the 3rd brakelight is unplugged. Any ideas on what the problem is
07 gt

157dB

Its a loss of ground common to both.
Look around in the trunk for the disconnected grounding point.
Either the ground on the trunk lid or the ground for the trunk lid.

Or its the wet SmartJunctionBox syndrom.
There S197s leak like a screen door on the
pass side under the dash.
The SJB gets wet and all the electrical items
powered by the SJB (trunk light, third brake light,
ect.) start to go wonky.
Its more prevalent on the 05s, 06s and most 07s.
It took Ford 3 model years to discover and fix the
problem. Check your cowl drains. Check your cabin
air filter for signs of water damage.
Pull the pass side door sill and have a look under
the carpet there. ANY signs of previous water
intrusion/damage?

You might have the dreaded water leak.
Any musty smells emanating from the inside
after she is closed up for the night?
Inside of the windows fogging up when
the temps are just right for dew to form?