Towing electrics

anothersunrise

We have just had to change the electrics on the tow bar. 

On the old electrics the ATC control fired up when the ignition was turned on.  On the new electrics it fires up as soon as the the plugs are connected.  

The old electrics dated from 2010

Any thoughts on

A, which is right

b, what are the implications (if any) on the new system 

First thoughts are battery drainage. 

 

Vulcan

Your electrics are wired correctly.

ATC requires power direct from the towing vehicle electrics and needs a constant 12 volt supply from either Pin 9 on 13-pin or Pin 4 on 12S 7-Pin electrics.

alfigone

Hi Anothersunrise,

Your new electrics are correct.  Assuming a 13 pin plug, your ATC should be connected to pin 9, which provides a permanent live to the caravan, regardless of the cars ignition.  It sounds like on your old electrics the ATC was wired to pin 10, which is usually for powering the fridge when travelling from the car & for enabling charging of the van battery when the car is running via pin 9.

As for battery drainage, there will be a small amount when the ATC powers up, but it should draw very little when it has been through its check, but it will depend on the caravan manufacture as to what pin 9 supplies in the van.  It should in theory not be able to charge your van battery until the car is running, but may welll supply 12 volts to your van lights etc, if your van battery is flat.  

Usually you'll start the car soon after connecting, so it shouldn't be an issue, but some people do disconnect the van from the car electrics when travelling on ferries etc. to minimise any drain.

Regards,

Paul

anothersunrise

Sorry meant to say it is a 13 pin