ae91 5afe reverse lights/wiring diagram

[l1ttle_d3vil]

the reverse lights on my 1987 ae91 (5afe engine) aren't working and I cannot work out why.

the bulbs are sweet. what triggers the reverse lights? is it a plug that goes into the gearbox, like on a manual car? if so, where abouts is this located? is it possible that this has fallen out?

otherwise where are the fuses for the reverse lights located? I checked every fuse I could find on the car and they are all sweet but maybe I missed some???

any help would be appreciated.
cheers.