13 pin continental socket

[Nidge1]

Hi,

I have recently taken delivery of a new BMW with a factory fitted tow bar which has a 13 pin continental socket.Everything works fine, apart from the fridge connection. The car has been back to the dealers and has had a feed/relay fitted to pin 10.In all the wiring diagrams it states that pin 11 is the return earth for pin 10.However the dealer is adamant that this is not the case and that a relay is fitted to pin 11.

He is reluctant to earth pin 11 due the relay.He does not seem able to offer any further advice to make the fridge work! Surely there must be a answer to the problem.

Has anybody had similar problems with the continental socket? or can throw any light on the matter.

Looking forward to your views.

Nidge

 

[Lutz]

Normally, pins 11 and 12 are redundant and pin 13 is the earth for pin 10 but you'd have to check how the socket on the caravan is wired up. In some cases, pin 11 is used as earth for pin 10.

 

[Lutz]

Normally, pins 11 and 12 are redundant and pin 13 is the earth for pin 10 but you'd have to check how the socket on the caravan is wired up. In some cases, pin 11 is used as earth for pin 10.

Sorry, of course I meant plug on the caravan, not socket.

 

[rob_jax]

Nidge and Lutz,

We have an Eriba Triton towed by a MB C270 with 13 pin electrics throughout.

The best information I have from various web-sites, checking my car with a voltmeter, is:

Pin 9 is the switched supply for the caravan internal lights

Pin 10 is the switched supply for the fridge (thick red wire)

Pin 11 is the dedicated return for pin 10 (thick black wire)

Pin 12 is unused

Pin 13 is the dedicated return for pin 9

After using the 13 pin system for some years, I'd never go back to the push-and-hope 12N+S system.

Robert

 

[Eddie1FromNottingham]

Nidge,

If you are a member of the Caravan Club there is an excellent Technichal Information Sheet available on their Web Site. This shows correct Wiring Diagrams for 13 pin, 12n, and 12s sockets. It's well written without the usual mumbo jumbo. Print it and take it to your Dealer.

Eddie.

 

[mike_5041102]

I'm in full agreement with Rob_jax, this is correct and is in accordance with the current caravan industry standard ISO 11446. On the car, Pin 9 is permanent live and pin 10 is live only when the ignition is switched on. I have joined pins 11 and 13 as this doubles the size of earth return with no negative effects.

 

[Nidge1]

Many thanks for all replies.I have spoken again to the dealer and he is sending his chaps out to look at car/caravan connections.

As Eddie suggested I did take the caravan diagram to the dealer and he is still adamant that the socket was wired correctly at the factory. However Mike your suggestion that the joining of pins 11 and 13 is a good idea totally contradicts the information in the caravan clubs technical sheet which Say's DO NOT join these pins together as this could cause the plug/socket to overheat. I will keep you posted on the outcome.

 

[Eddie1FromNottingham]

Nidge,

Further to my last posting, some years ago I had a problem with a newly fitted pre-wired "S" socket. Eventually after a lot of Head scratching an Auto Electrician dioscovered that Two connections had been reversed during manufacture, so it goes to show that you can't take anything for granted. Regarding the joining of earth connections in either 12s or 13 pin sockets this overloads whichever pin used causing scorching and eventual breakdown of the plastic housing leading to the brass pin breaking away from the socket. This has been widely reported in P/C Mag and both Club Mags. Of course it's o.k. to join the earth returns at the car body but never in the socket Hope you get the problem sorted

Regards Eddie.

 

[mike_5041102]

Many thanks for all replies.I have spoken again to the dealer and he is sending his chaps out to look at car/caravan connections.

As Eddie suggested I did take the caravan diagram to the dealer and he is still adamant that the socket was wired correctly at the factory. However Mike your suggestion that the joining of pins 11 and 13 is a good idea totally contradicts the information in the caravan clubs technical sheet which Say's DO NOT join these pins together as this could cause the plug/socket to overheat. I will keep you posted on the outcome.

Thanks for that Nidge but I don't understand why joining 11 and 13 together would cause an overheat. Pins 9 and 10, internal lights and fridge, can never be powered at the same time so the pins 11 and 13 will only carry the current of one or the other. Joining 11 1and 13 doubles the size pin available thereby reducing the ressistance and temperature. Can anyone explain why my thoughts are wrong?

 

[mike_5041102]

Thanks for that Nidge but I don't understand why joining 11 and 13 together would cause an overheat. Pins 9 and 10, internal lights and fridge, can never be powered at the same time so the pins 11 and 13 will only carry the current of one or the other. Joining 11 1and 13 doubles the size pin available thereby reducing the ressistance and temperature. Can anyone explain why my thoughts are wrong?

 

[rob_jax]

Mike,

You would think that by joining the two return wires - pin 11 and 13 together in the socket, that this would share the current load more efficiently?

The problem with this idea is that the fridge wiring is 30 Amp rated, whereas the internal lights wiring is lower rated - 10 Amp or less.

Splitting the return current from the fridge so that half of it goes down a low amp rated wire is not a good idea - and the thin wire from the socket to the body will probably overheat.

Robert

 

[Eddie1FromNottingham]

Thanks for that Nidge but I don't understand why joining 11 and 13 together would cause an overheat. Pins 9 and 10, internal lights and fridge, can never be powered at the same time so the pins 11 and 13 will only carry the current of one or the other. Joining 11 1and 13 doubles the size pin available thereby reducing the ressistance and temperature. Can anyone explain why my thoughts are wrong?

Mike,

The permanent live supply on pin 9 also charges the Caravan Battery via a relay in the 'Van. This can only happen when the Car Engine is running. Assuming that when you are travelling the Caravan Fridge is also set to operate on 12volts the combined load is too great for one neutral connection within the socket. This causes localised overheating of the earth pin used which in turn melts the plastic allowing the pin to come away from the socket. This has only been recognised with the advent of larger fridges/ freezers now fitted to some 'vans. In fact the power consumption of most fridges is close to the maximum load carrying capacity of either the Live or Neutral wires. Therefore joining the Neutrals only adds to this problem. As most of the 13 pin sockets come pre wired why alter them?. Incidently peculiar to the 13 pin Socket there is a third Neutral on pin 3. This is for all the lighting requirements. This should also be treated as a seperate supply. obviously it's acceptable to join all these at the point of connection on the vehicle chassis but not before. Hope this helps.

Regards Eddie

 

[mike_5041102]

Mike,

You would think that by joining the two return wires - pin 11 and 13 together in the socket, that this would share the current load more efficiently?

The problem with this idea is that the fridge wiring is 30 Amp rated, whereas the internal lights wiring is lower rated - 10 Amp or less.

Splitting the return current from the fridge so that half of it goes down a low amp rated wire is not a good idea - and the thin wire from the socket to the body will probably overheat.

Robert

Sounds convincing, thanks Rob.

 

[Eddie1FromNottingham]

Mike,

The reason that the neutrals should not be joined together in the sockets 12s or 13 pin is as follows. The permanent live supply on pin 4 in the 12s and pin 9 in the 13pin is also an ignition controlled supply providing Battery Charging for the 'van Battery via an onboard Relay. Assuming that whilst travelling the Fridge is set to operate on 12V and Battery Charging is taking place the combined total load is too great for one return. In theory the power consumption of a modern Fridge / Freezer on 12volt is at the maximum of either the supply cable or the return,as mentioned earlier by Rob-jax, therefore since 1998 12s Sockets have incorporated 2 neutral returns, pin 7 for the fridge and pin 3 for interior lighting and charging. On the 13 pin versions it's pin 11 for the fridge return and pin 13 for the interior lighting and charging.

Incidently in the 13 pin there is a third return on pin 3. This is for all the road lighting requirements. Clearly it was the design intentions to keep all the supplies as seperate circuits. And the need for two earths for fridge and charging was in order to keep cable thickness (gauge)to sensible proportions. It is of course acceptable to attatch the Earths to the same point on the vehicle body.

Overheating damage to supplementary Sockets is well documented and has been featured in P/C and both Club mags. The damage mainly occures in 12s sockets when pin 7 only is used as Neutral this has the effect of causing localised scorching around the pin with the eventual failure of the plastic centre, allowing the pin to detatch itself from the socket, this either then pulls the pin out when you withdraw the plug, or it remains loose within the socket with the possibility of comming into contact with the permanent live resulting in a dead short and at best a blown Fuse. Owing to the high temperature of this, the Earth Wire screwed into pin7 (Black) is usually so brittle that unless there is plenty of slack in the Harness a complete rewire is required. As most wiring kits that I have seen are pre wired why alter them? All this I learned whilst assisting a mate who is a towbar Fitter. For the benefit of others, who are members of the Caravan Club there is a Technical Help sheet on their members only Web Site. I hope the above helps.

Eddie.

 

[mike_5041102]

Seems like I'm a silly boy then. I'll revert to the correct earthing at the first opportunity.

 

[chris_5068897]

Nidge and Lutz,

We have an Eriba Triton towed by a MB C270 with 13 pin electrics throughout.

The best information I have from various web-sites, checking my car with a voltmeter, is:

Pin 9 is the switched supply for the caravan internal lights

Pin 10 is the switched supply for the fridge (thick red wire)

Pin 11 is the dedicated return for pin 10 (thick black wire)

Pin 12 is unused

Pin 13 is the dedicated return for pin 9

After using the 13 pin system for some years, I'd never go back to the push-and-hope 12N+S system.

Robert

I agree wholeheartedly. I have the 13 pin system fitted to my BMW and its much more secure. Its hard to see why manufacturers haven't switched?

 

[Eddie1FromNottingham]

Nidge,

have you an update please.

Eddie.

 

[mike_5041102]

Pin 12 is not used on the 13 pin plug so may be useda s an extra earth pin if required

 

[Eddie1FromNottingham]

Pin 12 is not used on the 13 pin plug so may be useda s an extra earth pin if required

Mike,

although pin 12 is "unused" it's correct function is sensing device. This was primarily a continental application designed so that the the Caravan could send a signal to the electronics on the car there by making adjustments to Auto Gearboxes Braking Etc. Initally there wasn't any production vehicles with this ability. So pin 12 was redundant. (However I have been reading threads on here indicating that Merc's and other Continental Cars are now fitted with Electronic Stabilization Etc. I don't know if it's controlled by this method.) It is considered bad practice to use this as a neutral as it makes the installation non-standard. It is quite possible that continental Manufacturers are using pin 12 on the 'van side of the plug to provide 12 volts for this perceived application, obviously if someone decides to use 12 as a Neutral there would be a dead short. This also applies to pins 2 and 5 on the 12s socket. It is advisable to keep any wiring to the published standard otherwise when the Car is sold on the new owner could be faced with an expensive repair, it is also feasible that changing the 'Van for a new Continental Type could cause the same problem.

Eddie.

 

[Nidge1]

Nidge,

have you an update please.

Eddie.

Hi Eddie,Sorry I have not given an update as I have been on hols for 10 days (no fridge en route) My caravan has also gone in for a service and the dealer wants car and caravan to sought out the problem.I will certainly give you an update as soon as possible.

Regards Nidge

 

[Nidge1]

At last!!

The BMW dealer has at last cracked it.As most people have said pin 11 goes to earth and low and behold it worked. He did admit that he was following a wiring diagram for a pre 98 van and this did not show the correct wiring details. Just goes to show that even the experts don't always get it right!. Once again many thanks to all who replied.

Regards

Nidge