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Hi,
I apologise in advance to everyone out there who hates caravans, but.....
I am after some advice on wiring the second (auxiliary)socket on the towbar for my 1995 9000 CSE.
Got the standard electrics sorted ok, just after some pointers for the second one.
I have tried the 'forum search' several times and not found anything so far.
Thanks in advance
Wayne
 

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Did a 9000 CDE a couple of years ago and a 9-5 last weekend. The easiest way is to use a smart relay, Towsure sell these for about £10 which takes a feed direct from the battery and then switches when the voltage is above about 12.7 volts (i.e. engine is running) to give feeds for the fridge and battery charging as well as the permanent feed for the caravan internal lights. Using this requires only one wire to be run from the front to the back, a separate ignition controlled feed is not needed. Also saves possibility of the caravan battery feeding back to start the car if car battery is flat, prevents causing car battery to go flat if ignition switch on but car not running and the fridge left on.

To install
- run 21 amp (minimum) wire to the boot from the battery where it connects (bolts) to the wiring. Use a yellow crimp on fastening. Use 15 amp blade fuse at the battery end. To run the wire means lifting carpets along the left hand sill. I fed the wire through the bulk head with the car loom. For the 9-5 there is already a 12v supply from the battery in the towing socket in the boot.

- This 12 v suply goes to the smart relay.
- Connect an earth to the relay - I used 21 amp wire and bolted to a hole drilled on the body.
- From the relay connect to the 12S socket wires for 12v, battery (aux) charging, fridge.
- From the socket connect pins 7 and 6 (I think) to earth. I used yellow crimped connectors to go over the new earth bolt. These need to handle the same current as the feed wire hence 21 amp minimum.
- This should leave one spare wire from the socket which is not used.

Note the 12S socket is connected slightly different for pre 1999(approx) caravans to the later ones.

If you need help on the 12S socket wire colours let me know.
 

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Few details now I have checked my paperwork.


12S socket.
Pin 1, yellow wire - goes to car reversing lights from the car boot towing electrical connector (I think I did this using a blue spade connector to the Saab 9000 boot towing socket).

Pin 2, blue wire - goes to caravan battery charging, from smart relay aux(or ignition controlled relay if not using a smart type which senses battery voltage increase when engine is started - about £10 from Towsure). Caravan Club handbook says this connection is not used on new caravans and on some imported caravans is used as an earth point so it is worth checking the caravan handbook. On the new caravans they must use the permanent 12v supply and have a relay on the caravan for battery charging. Our caravan is a year 2000 model and connecting as above has not given any problems but means the car can be used for older caravans.

Pin 3, white wire - goes to earth point on car, provides caravan earth return. Use yellow crimp connector.

Pin 4, green wire - permanent 12v supply from car battery through a 15 amp fuse. Powers caravan lights. On smart relay goes to 12v output.

Pin 5, brown wire - spare wire and not used, just tape back to the other wires.

Pin 6, red wire - goes to caravan fridge. Connects to smart relay fridge or ignition controlled relay.

Pin 7, black wire - earth return for caravan. Connect to car earth point. Use yellow crimp connector.

Car 12v positive supply - use a 21 amp minimum wire from the car battery (use yellow crimp connector) with a 15 amp blade fuse at the battery end. Connect to the smart relay.

Provide an earth point in the car boot, drill a hole, clean off the paint and then bolt the earth wires using crimped yellow round connectors. Connect the 12S socket white and black wires and also an earth wire to the smart relay (or ignition controlled relay).

If using a separate ignition controlled relay for the caravan fridge and battery charging, then the 12v positive feed from the car battery could also be used split to give the permanent supply and the ignition controlled relay supply. A wire will need to be run from an ignition controlled supply to the relay which means digging around under the dash board.
 
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