I have a trust tow bar fitted to my FL2, seems to work ok when the electrics are connected up to my Erde 143 trailer. i.e. all the standard lights work on both and the rear parking sensors are off when connected up.

But when i put the rear fog lights on, they dont work on the car with the towing electrics connected but work fine when its disconnected.

Is this a standard feature so as not to reflect the rear fog light output off the trailer or could it be a fault ? Its not a major issue just a query.

Its designed that way so that if towing a caravan or similar then you don`t get the glare from the car foglight reflecting back and possibly affecting your rearward view in the mirrors.

What he said

perfect, thanks guys confirmed what i thought