[cb750chris]

Hi Ian,
The "official" way was to use the orange/slate wire to provide the permanent live to the towing electrics, and then do the switching inside the car.
Probably the easiest way to do this is with a volt sensing relay, as these only require the battery supply and a return, then switch on when the battery voltage reaches ~13.5 volts.


Officially the towing eclectics gets it's supply from one of the fuses that feeds the Light switch, however if you look not very hard, then there is a spare fuse position in the under-bonnet fuse box (reserved for the self leveling suspension that we never got), this spare position goes to a spade connector that is unused, so could be utilized to provide an independent feed to the towing electrics (But you would need an additional fuse to fit there). This is what I have done, as this allowed me to have independent fuses for car lighting and caravan electrics.


Hope this is of some help
Chris