have u got the grey plug the fits on the socket on your tow bar? u will find it only works when u start the car. stops u from flattening your battery, 12 v is only used when u are mobile. just to keep the fridge cold. so put your fridge on 240v or gas, get it cold. then when u are mobile it keeps it cold, .
------------- Roughing it in style at Calloose caravan and camping holiday park nr St Ives.(seasonal pitch)
Its not a hangover, its wine flu!
If you are not getting the 12v light on the fridge, you need to check the wiring on your towcar, if this is all correct it could actually be the LED not working (Very rare).
it may not light when its just on tickover, as the alternator wont be giving full power, get someone to rev the engine, around 1500rpm should do it, then it will come on