wire for back up camera

They say my 09 Tocoma is pre-wired for the back up camera
and I do have the camera in the tail gate. The harness is
supposed to be in the headliner above the mirror and yes I
feel a small slot, but before I go pulling down the headliner
where is the wiring harness and how far do I pull the headliner
down, I don't want to screw the headliner up. Can I fish for
the wire with a small hook ? Any help would be appericated.
I plan om installing a Gentex mirror and their video install seems like
it's so simple, but they don't mention pulling the headliner down.

 

Hi, EXPI
I have the 09 with the tiny LCD back up screen on the back up mirror, how come u don't have yours?

 

you could remove the whole map light assembly (1 screw, a few clips) and probably reach in there and get it without have to fish it out

 

I didn't buy the whole package. Just a standard model.

 

Great idea thanks.