Afternoon all,

We tow a caravan with our Disco but the 'Supplementry Socket ' '12s' has never seemed to be working, i.e the fridge doesn't cool whilst we are travelling.

Anyway for one reason or another I have never got round to looking at it until today. Got the wiring diagram for the plug sorted , got my test meter and off I went. The wiring is fine, but the test meter reads nothing.

I've had an auxillary power socket kit for the boot for some time so I thought whilst I was at it I would fit this. To fit it you have to remove the panels to expose the wiring serving the rear light cluster. It so happens that this is where the trailer electrics come into the vehicle.

When all the panels were removed it was obvious why the fridge wasn't cooling whilst travelling. Out of the seven wires on the supplementry socket wires only 2 were connected the yellow 'reversing wire' and the green 12v power ( only reading 4.1 on the meter ). The red 'fridge' wire connected to nothing.

How do I connect the red ( fridge ) and blue ( battery charging ) wires , apparently I need a relay for the fridge wire to prevent drain if the engine is turned off.

Help ??????

yes you do need a relay, land rover normally use a voltage sensitive relay whch will only supply power to the caravan battery when the alternator is charging.

another way would be to use a normal relay, you can wire it as follows:-

30-battery
85-ignition live (NOT accessory live (ignition pos1))
86-earth
87-fridge/caravan battery

use two relays as not to overload them, 1 for charge the other for the fridge or check to see what amps the fridge and battery will need and wire in 1 heavy duty relay to run both, the only downside to this is that when you turn the ignition on without running the engine, the vehicle battery will be powering the caravan and therefore run down the vehicle battery, so make sure the engine is running

Many thanks for your help. Sorted today with relay etc.

Mark