Genuine octy Towbar wiring?

[martziniuk]

Hi,

I think i will finally get around to fitting my tow bar this weekend but i have a question about the wiring on a genuine tow bar.

There is a relay box on tow bar wiring which has lots of wires coming out of it. I know where nearly all of them go but one has stumped me.

Its the red one in the pic near the box, its long enough to go to the front of the car and is plugged into position 30 on the relay box as shown. Anybody know where it goes and what it does?

[rwbaldwin]

Hi,

I helped a friend fit a towbar for a trailer and we had the same problem. There was a helpline so he called. Turns out it is for a fridge in a caravan so we left it unconnected.

[martziniuk]

Hi,

I helped a friend fit a towbar for a trailer and we had the same problem. There was a helpline so he called. Turns out it is for a fridge in a caravan so we left it unconnected.

:confused: seriously?

But thats mad.

[rwbaldwin]

I'm not sure now either, but as far as I know his trailer lights all work OK.

I am looking at the pin-out of the 7-pin connector on the trailer and this is what I found.

12n Plug & Socket Wiring (black)

Pin 1 = Yellow - Left Hand Indicator

Pin 2 = Blue - Rear Fog Light

Pin 3 = White - Chassis

Pin 4 = Green - Right Hand Indicator

Pin 5 = Brown - Right Hand Tail Light

Pin 6 = Red - Brake Lights

Pin 7 = Black - Left Hand Tail Light

Hope this helps

[martziniuk]

I think mine must be different. I have connectors which plug into existing light sockets on the rear car lights, in fact the are loads of wires but they all plug into places i know about.

Its just the lone Red one which has been snipped by the previous owner.

[rwbaldwin]

Just spoken to next door and got the full story. Caravans have two sockets and if you want a reversing light on a trailer you need two sockets too. Most people don't so I guess this would be for a reversing light - unused on a single trailer socket.

Does this make any sense?

[cjb]

There are 2 types of socket, 12n and 12s. The 12s has the extra wire to run the fridge.

Helpful Information - Trailers, Towing, Trailer wiring, Erde & daxara trailers

That's what the long wire is for. Caravans are wired 12s, trailers usually 12n.

That's why some cars have 2 sockets- 12s & 12n.

[martziniuk]

Maybe i should make myself more clear, the red wire comes out of the relay box and goes to nothing as its been snipped. The towbar socket is already pre-wired.

I was maybe thinking it powered the relay box from the fuse box? or maybe something for the dash so that when the indicator is on the towing light on the dash flashes?

thanks for suggestions so far.

[rwbaldwin]

Back to basics...

To make a relay box work you will need inputs from light circuits, outputs to the socket, ground and a cable to the battery (via a fuse - not switched as you need the hazards to work).

From what you are saying, the red wire needs to go to the battery via a fuse. If you open the relay box the red wire should feed the contacts for all the relays. Is the red wire thicker than the input wires?

[martziniuk]

Yes the red is a little thicker than the other wires also it has a loose black sheath around it.

So i just need a permanent live i think as the box is linked to the back lights and the socket and there is a ground, hmmm. What amp or which circuit would i need ?

[rwbaldwin]

Just noticed that Fuse 35 is a 30A fuse for a towbar 12V socket.

I guess that this finally answers your question. On a stealer installed towbar, that cable will go to position 35 on the fuse box. That maybe the reason it was cut.

Fuse 35 is middle column, 2 rows up from the bottom row.

You may just want to use an inline fuse to the battery.

[martziniuk]

excellent,thats helped me a lot, many thanks for your time.