On the 2012 plus 4 the relays are behind the dashboard, so only accessible if dash is removed.
The fuses however are on the underside above the gearbox tunnel, and they can easily work loose due to gravity.
Yes, and the fuses really don't have to come out very far to break the circuit. I fixed an issue with a mate's +4 recently, the indicators had stopped working. He checked the fuse and it looked ok but when I went over it the fuse wasn't actually fully bedded in its socket, even though it looked like it.
I would be unsurprised if a trip down a bumpy road could loosen a fuse or a relay sufficient to break a circuit even though looking like it was in place ok.
