I have 2002 2lt Ducato and find that rear lights are lighting wrong bulbs,
ie brake = fog and reverse / fog= brake light / back lights = dim. I suspect an earth fault and will try this when rain stops. Has anybody had this fault before. (body is hymer 494). Also strangely the o/s fog light has no wire attached?
I am confused. Any help appreciated.

Many Euro vehicles and some late Japs only have one rear fog light. Recheck your rear lights before you perform surgery on them, some models tail and rear fog shared a bulb, and stop was in a different holder. If you have a definite fault, then check earths first, then check for dodgy trailer skt wiring.

Cheers AArk Thanks for suggestions. Spent the morning replacing every
wire to bulb connector on both sides. All were grotty and corroded.
Also replace N/S reverse light bulb which was intermittent on my meter and in situ. (looked Ok but).
All lights came on in the correct place. Found missing fog lamp wire it had
disconnected and fell into the rear bumper.
This problem was a new one for me normally a corroded fitting meant the light did not work.... Fiat are different without a doubt.