Permanent live on 7 pin tow socket?

CaptLimey · 03-11-2010, 19:17

Hi all.

Having just plugged the trailer into the 7 pin tow socket of the new (to me) '03 3ltr T2, I found that the trailer's rear high intensity fog light was on permanently.

Traced it back to the tow socket having a permanent 12v live terminal feeding the fog light cable on the trailer circuit. It seems that the car is wired to supply a caravan with 12v permanently, when connected, but does not appear to have a separate supply for the trailer's high intensity rear fog light.

I've managed a temporary work-around to overcome this but is this a normal wiring system?

Regards CL

rustic · 03-11-2010, 19:22

For older vehicles / caravans, there was only 1 7 pin socket, so the spare pin supplied power to the caravan.
Later, rear guard lights became common, so they used the pin for that so if you have a camping trailer or bike rack No. Plate, you won't need a second socket.

For later caravans, they added the Supplementary socket that had all the belts and braces, power, fridge supply, reversing light etc.

CaptLimey · 03-11-2010, 21:33

Thanks Rustic that explains it. My caravan has it's own on board battery charged from site and/or solar power. It also has a rear guard light so I think I'll stick with the 'spare' pin supplying the light rather than 12v power to the 'van.
Rgds CL

rustic · 03-11-2010, 21:48

Quote:

Originally Posted by CaptLimey

Thanks Rustic that explains it. My caravan has it's own on board battery charged from site and/or solar power. It also has a rear guard light so I think I'll stick with the 'spare' pin supplying the light rather than 12v power to the 'van.
Rgds CL

If you want to be really smart, you could have a toggle switch in the boot, with centre pin to the socket, one to the +12 Volts and the other to the Rear guard light.
Label the switch then you can tow anything without re-wiring.

Thomas-the-Terrano2 · 03-11-2010, 23:08

is this french wiring on 12n as said fog lights been on go some time,

think on uk spec to late 70s?

often wonder if live pin on 12s should be isolated in car, in case should
damage socket either off roading or someone wraps themselves round
your towbar!

btw latest wiring spec means split charge pin isnt connected as modern
caravans charge from the live feed, and know if are being towed.

suspect the charger circuit in van senses the voltage coming thru, though
there is still a relay in car to run the fridge line, ideally based again on
fact the altenator is making more volts than the battery does with engine
off.

wildbri · 03-11-2010, 23:43

aye aye Cap'tn, pleased to hear that you got hold of a 3l terrano, is a left h d? If it's a French one I guess it was quite costly. Regards towing wiring, I added the 12s socket to my t2 so that I can use the fridge and charge the battery whilst the engine is running, there is also a permanent live which can be used to power the caravan on site which we used before
caravans batteries or can be used if the caravan battery is defunct. I am adding a link see if it works. regards bri

http://www.caravanclub.co.uk/media/1...-wiring-mo.pdf

03-11-2010, 19:17	#1
CaptLimey Senior Member Join Date: Nov 2007 Location: South of France Vehicle: '03 LWB MK.4 3Ltr T2 Posts: 421	Permanent live on 7 pin tow socket? Hi all. Having just plugged the trailer into the 7 pin tow socket of the new (to me) '03 3ltr T2, I found that the trailer's rear high intensity fog light was on permanently. Traced it back to the tow socket having a permanent 12v live terminal feeding the fog light cable on the trailer circuit. It seems that the car is wired to supply a caravan with 12v permanently, when connected, but does not appear to have a separate supply for the trailer's high intensity rear fog light. I've managed a temporary work-around to overcome this but is this a normal wiring system? Regards CL Last edited by CaptLimey; 03-11-2010 at 19:19. Reason: Additional information

03-11-2010, 19:22	#2
rustic Senior Member Join Date: Feb 2007 Location: Staffordshire Vehicle: Maverick Mk I 2.7 TD LWB Posts: 7,825	For older vehicles / caravans, there was only 1 7 pin socket, so the spare pin supplied power to the caravan. Later, rear guard lights became common, so they used the pin for that so if you have a camping trailer or bike rack No. Plate, you won't need a second socket. For later caravans, they added the Supplementary socket that had all the belts and braces, power, fridge supply, reversing light etc. __________________ Ford Maverick GLX 1995 2.7TD LWB in illusion silver, 98k miles. Owned since new, for 22 years. Best car I have ever owned. Just wish I could drive it more.

03-11-2010, 23:08	#5
Thomas-the-Terrano2 Moderator Join Date: Dec 2004 Location: Hackenthorpe Sheffield Vehicle: Terrano2 R20 lwb 2.7TDi Posts: 5,234	is this french wiring on 12n as said fog lights been on go some time, think on uk spec to late 70s? often wonder if live pin on 12s should be isolated in car, in case should damage socket either off roading or someone wraps themselves round your towbar! btw latest wiring spec means split charge pin isnt connected as modern caravans charge from the live feed, and know if are being towed. suspect the charger circuit in van senses the voltage coming thru, though there is still a relay in car to run the fridge line, ideally based again on fact the altenator is making more volts than the battery does with engine off. __________________ M6YTB / 20YTB '60' 2010 Ford C Max Zetec 1.6i, black '56' 2006 Jeep Grand Cherokee 3.0TD, silver 2021 Bailey Pegasus Grade SE Turin caravan Smile, its more likely to confuse. One Life, Don't Just Live It, Drive a Nissan, or ...... a Jeep. Owner of Nissan 4x4s 2005 to 2019, and maybe in the future too!

03-11-2010, 21:33	#3
CaptLimey Senior Member Join Date: Nov 2007 Location: South of France Vehicle: '03 LWB MK.4 3Ltr T2 Posts: 421	Thanks Rustic that explains it. My caravan has it's own on board battery charged from site and/or solar power. It also has a rear guard light so I think I'll stick with the 'spare' pin supplying the light rather than 12v power to the 'van. Rgds CL

03-11-2010, 23:43	#6
wildbri Senior Member Join Date: Feb 2007 Location: south lakeland Vehicle: terrano 1997 tdi Posts: 940	aye aye Cap'tn, pleased to hear that you got hold of a 3l terrano, is a left h d? If it's a French one I guess it was quite costly. Regards towing wiring, I added the 12s socket to my t2 so that I can use the fridge and charge the battery whilst the engine is running, there is also a permanent live which can be used to power the caravan on site which we used before caravans batteries or can be used if the caravan battery is defunct. I am adding a link see if it works. regards bri http://www.caravanclub.co.uk/media/1...-wiring-mo.pdf