Welfare van electrics

[Gary bg]

Hi all.
Just purchased 2011 ex newrok rail van and have what seems to be a normal thing with these in a power problem to the back. I looked through the posts but can't seem to find my particular issue. After tracing the wires from the switch the on the dash which doesn't light up, I traced them back to the switchboard and to a yellow plug that is just hanging down. There are two screw holes on the back of the switch board where something has been removed,and is probably where this plug goes. Does anyone know what this would be thank you.

[JR1983]

Did you get to the bottom of this as we seem to have the same problem, any help would be appreciated. Thank you