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Andyrt200

Getting all the pins in OE towbar electrics or making a caravan fridge work

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BMW (& many other manufacturers) don’t put full electrics in their towbar sockets, it’s been posted about many times before, but I’ve only found information on F cars so I’m starting this for Gs. 
 

First off they don’t put all the pins in because most trailers, bike carriers etc don’t need them, this is my car trailer:

rrh7am2.jpg
 

There are actually 5 pins missing in that, one is never used the other 4 are power & ground for a caravan. 
 

Obviously I only want to tow exotic cars to the race track, but life dictates having a working caravan fridge would also be useful (I actually drive the track cars to trackdays). 

I’m fitting the factory retrofit wiring to our G31 540i just for the sake of it really, it will go back to our local dealer to be coded & then it will hopefully be listed with an official retrofit removable towbar. I’ll do a different thread about that. 
 

However that then leaves me in the same boat as anyone who ticks the towbar option on their new G3X with some of the connections missing for caravan use. 

I contacted the site sponsors Cotswold BMW parts who were very helpful, though suggested I went to my local dealer as it would be complicated & I’d need to go back for the official coding also. My local dealer have been very helpful too but they didn’t know anything about the missing pins. Cotswold did though & explained that having all the pins is a dealer only option on new cars, they kindly gave me the official instructions but they actually say to cable tie an aftermarket relay in, exactly what I was trying to avoid by paying out huge amounts of money for factory kit! I could have just got a dedicated aftermarket wiring kit for a G3X car that would have had all the pins connected….

 

So this is where I am at the moment:

ayhEc1V.jpg
 

kgYm621.jpg
The socket with power & ground missing for the caravan fridge. 

There is this

Very useful thread from @535i Andrew @dandle & @DayvG I think they were saying on the F cars some actually had all 4 pins (same ones missing from my car trailer) missing. Getting the connections into the plug isn’t too hard with a detachable towbar & it’s well covered in that thread. According to the official instructions you have to get a new socket for the retractable towbars. 
 

In that thread they seem to have used connector X268, only this where the difference with F cars seems to be they are I think talking about connector X269. X269 in my kit is a 12 pin. 
 

This is my X268 6 pin connector:

7VEizQh.jpg
 

This is the wiring diagram I got with the reto fit instructions:

hEE3XgO.jpg


Back up in the picture with the two half’s of connector X268 in my hand the left one is the one running from the AAG module, it has all 6 pins fully wired, the one on the right goes to the 13pin trailer socket “R” or B* on the wiring diagram, that has three missing. The left one fully wired one has two 1,5 thick wires, both labeled as red black on the diagram, one is pin 3 connected directly back to fuse F284, that connects to pin 9 in the 13 pin trailer socket. The other 1,5 wire is actually red violet & goes back from pin 6 in X268 to the AAG pin 1, I’m wondering what that’s for? I think they were discussing that wire in the other thread. It’s possibly provision for fridge power but it’s only a 1,5 cable when the tow other brown ground wires are 2,5. 
More confusing are the other two 0,75 wires from pins 1 & 2 in X268, I guess they’re probably something to do with control of the retractable towbar, meaning the other could be too. I don’t know where to find any other wiring diagrams for the newer cars, my links & programs are only for the old E cars. The other thread has lots of links to newTIS but it’s been closed down now. 
 

It’s probably safer to just follow the official instructions for G cars & put in a separate relay (show in the linked thread) taking power from fuse 220 (red cable) & switched input from fuse 208 (violet cable) marked here on my new “high” fuse board:

 

FPnuNNA.jpg

Here’s the back for reference:

mypZlp4.jpg
 

Interestingly (for a select few anyway!) those same fuses are also in the normal fuse board:

 

5iP5WCK.jpg
 

Again the back for reference:

c2rlfzl.jpg
 

There are a lot more fuses there than wires on the back! The fuses are already there in 220 & 208 but luckily nothing is connected to the back, yet!

 

You need pins to connect to the back of the fuse board, I come back & edit this once I have them & know what I’m doing, I’m still waiting for my AAG control unit to come into BMW at the moment too. 

Edited by Andyrt200
Correcting fuse 208 position

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Quote

The other 1,5 wire is actually red violet & goes back from pin 6 in X268 to the AAG pin 1, I’m wondering what that’s for?

 

X268 pin 6 terminates at Pin 10 on the towbar socket.

 

Quote

I think they were discussing that wire in the other thread. It’s possibly provision for fridge power but it’s only a 1,5 cable when the tow other brown ground wires are 2,5. 

 

 

Quote


More confusing are the other two 0,75 wires from pins 1 & 2 in X268, I guess they’re probably something to do with control of the retractable towbar, meaning the other could be too.

 

X268 Pins 1 & 2 are for the motor in the retractable towbar as you assumed.

 

image.png.5d937cafc81af151ef627f0f86f79511.png

 

 

Edited by Matthew Ashton

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43 minutes ago, Andyrt200 said:

It’s probably safer to just follow the official instructions for G cars & put in a separate relay (show in the linked thread) taking power from fuse 220 (red cable) & switched input from fuse 208 (violet cable) marked here on my new “high” fuse board:

UTxPKRT.jpg

 

 

The circled fuse is fuse 206 which supplies the cooler box in 7 series cars.

 

Fuse 208 is the first 5amp fuse in that row and it feeds Night Vision electronics.

 

 

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24 minutes ago, Matthew Ashton said:

 

 

 

X268 pin 6 terminates at Pin 10 on the towbar socket.

 

 

 

 

X268 Pins 1 & 2 are for the motor in the retractable towbar as you assumed.

 

image.png.5d937cafc81af151ef627f0f86f79511.png

 

 

 

Thanks very much, that explains a lot & fills in the missing parts from the other thread, I think the wiring diagram posted on the other thread was probably wrong showing connector X268 as X269 then. 

 

Interesting to see X268 pin 6 going to Pin 10 on the trailer socket, that wire is missing on mine, as discussed on the other thread, also mentioned is the lack of pin 11 on the trailer socket on any of the wiring diagrams.

 

I can connect X268 pin 6 to pin 10 on the trailer socket no problem but with pins 1 & 2 on X268 already being populated for the retractable towbar (as you confirmed) I haven't got any spare connections for the extra ground wire needed for pin 11 on the trailer socket. It's not exactly hard to run that pin 11 directly to ground, it just odd its missing from the wiring diagram, maybe it's because there wasn't any space left for it in X268! 

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38 minutes ago, Matthew Ashton said:

The circled fuse is fuse 206 which supplies the cooler box in 7 series cars.

 

Fuse 208 is the first 5amp fuse in that row and it feeds Night Vision electronics.

 

Thanks for pointing that out, I was looking at my picture & the 6 looked like an 8! Looking at the actual fuse board I see it is 206 at the top, I've corrected my original picture now.   

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1 hour ago, Andyrt200 said:

 

Thanks very much, that explains a lot & fills in the missing parts from the other thread, I think the wiring diagram posted on the other thread was probably wrong showing connector X268 as X269 then. 

 

Interesting to see X268 pin 6 going to Pin 10 on the trailer socket, that wire is missing on mine, as discussed on the other thread, also mentioned is the lack of pin 11 on the trailer socket on any of the wiring diagrams.

 

I can connect X268 pin 6 to pin 10 on the trailer socket no problem but with pins 1 & 2 on X268 already being populated for the retractable towbar (as you confirmed) I haven't got any spare connections for the extra ground wire needed for pin 11 on the trailer socket. It's not exactly hard to run that pin 11 directly to ground, it just odd its missing from the wiring diagram, maybe it's because there wasn't any space left for it in X268! 

 Probably silly idea but could you not bridge pin 11 with pin 13 inside the towbar socket as they are both ground anyway?

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58 minutes ago, Matthew Ashton said:

 Probably silly idea but could you not bridge pin 11 with pin 13 inside the towbar socket as they are both ground anyway?


Its not a silly idea and one I’ve toyed with but the literature I’ve read says bridging pins in the 13 pin socket or plug is not recommended, I’m assuming it’s incase the pins or single wire used as the point to earth are then overloaded with current, overheat and cause a world of pain. 
 

 

Nice work @Andyrt200

 

have you seen this thread of mine albeit for F series?  But the theory is the same. 
 

 

I bypassed the BMW connectors you are wanting to use and essentially made up my own independent loom to give power to pin 10 when engine is running for cooling beers. 


In the my link above is another thread which shows you how I made up the necessary loom to get pin 10 working as it should. 

 

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15 hours ago, Matthew Ashton said:

Probably silly idea but could you not bridge pin 11 with pin 13 inside the towbar socket as they are both ground anyway?


As 535i Andrew said you shouldn’t really, I’ve seen that in a good few wiring instructions. 
 

However with the ground cable to pin 13 on the trailer plug being 2.5 & the power to both 9 & 10 being 1.5 you’d likely get away with bridging.
 

14 hours ago, 535i Andrew said:

have you seen this thread of mine albeit for F series?  But the theory is the same. 

 

Yes, it’s useful & that idea would work for most cars. Of course you also added thicker wires doing that too. It’s basically the same idea as the official dealer retro fit relay, except you have connected directly to the battery rather than the fuse board. 
 

I shall update more once I’ve installed everything & had it coded, I see if I can get an opinion from the master technicians at BMW when its in. 

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4 minutes ago, Mr H said:
15 hours ago, 535i Andrew said:

for cooling beers

I fully support that prioritisation :mrgreen:


It would be nice but our fridge is usually too full of food & drinks for the kids :roll:

 

At least the ice will sill be frozen for something stronger! 

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On 30/07/2021 at 12:02, Andyrt200 said:


It would be nice but our fridge is usually too full of food & drinks for the kids :roll:

 

 

See that's where you are going wrong.

 

On 30/07/2021 at 12:02, Andyrt200 said:

At least the ice will sill be frozen for something stronger! 

 

Although please tell me you aren't putting ice in whisky......:lol:

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27 minutes ago, 535i Andrew said:

Although please tell me you aren't putting ice in whisky......:lol:

 

No not a whisky drinker I'm afraid with or without ice, usually vodka or gin. On the plus side the kids get through the food quickly so that makes room for beer :)

 

Back on towbars, I've been looking a bit at used electric retracting ones (from G30 / 31s) & the ones who show the 13pin socket have actually got all the pins in, of course no idea if they are actually all connected up!

 

Mathew pointed out in the UK the detachable one was never an option on new G3X cars, you could apparently only opt for the electric retracting one.  

 

I wanted to get a Westfalia detachable, but no one has any stock at the moment & can't give me a date to get any in. I just realised it seems I only need to add the switch to all the factory electrics I've got (still waiting for the actual trailer module) & I could put on a used retractable. BMW said it should be ok to code in, but it gets a bit messy with my plan to have it all official when the retro fit kit I got was for a detachable!  

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7 minutes ago, Andyrt200 said:

 

Back on towbars, I've been looking a bit at used electric retracting ones (from G30 / 31s) & the ones who show the 13pin socket have actually got all the pins in, of course no idea if they are actually all connected up!

 

 

When viewed from the front of the socket, yes they appear to have all the pins present,

 

IMG_3929.jpg

 

but when you take the socket apart they aren't wired up/electrically connected in my case

 

dr-4367.jpg

 

or are wired but are not electrically connected to to anything in the car.  

 

My dads G01 has the same socket part number as mine (as I have a newer towbar fitted on my car than was originally fitted).  All pins are present (he won't let me take his socket apart) but he has no ignition on supply and suffers from warm beer.

 

image.jpg

 

He drinks Budweiser which I wouldn't even call beer so no great loss.

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12 minutes ago, 535i Andrew said:

He drinks Budweiser which I wouldn't even call beer so no great loss.

 

:lol:

 

The rest was very interesting too, if I do get a retracting one I shall be taking it apart so will let you know. 

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A very interesting thread because I am looking to get a 7 series and tow with it. At least compared with a Mercedes S class there is a dedicated wiring kit. 

 

I can see why there is no feed for the fridge. If it was a permanent live then the drain would kill the car battery if the caravan was connected and the car off. If the 12V for the fridge was ignition switched it's still a massive load when car isn't running.

 

I guess what I'll be doing is something I did before on a different car and that's fitting a smart relay. It only switches the fridge supply on when the alternator is running by detecting > 13.5V. It may not be perfect if the car is managing the alternator but it would be a decent and safe solution.

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2 hours ago, JasonH said:

 

I guess what I'll be doing is something I did before on a different car and that's fitting a smart relay. It only switches the fridge supply on when the alternator is running by detecting > 13.5V. It may not be perfect if the car is managing the alternator but it would be a decent and safe solution.


That’s exactly what @535i Andrew did, there should be a link to what he did back up this page a bit. You can use the fuse output I showed to connect the smart relay to instead of direct to the battery if you wanted. I think the fuse board is the same on a 7 series. 
 

I’m still waiting for my OE AAG (trailer unit), the semi conductor shortage is causing a big delay. I will have been waiting a month if it actually comes in next week. It looks like there is a switched output on that, but I won’t know till I actually get it! 

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@JasonH

 

You want the fridge to be on an ignition on only supply as it’s such a big load you will start draining the battery if using a permanent supply from the moment you hitch up till you unhitch. 
 

If the fridge is controlled by a smart relay it won’t drain the battery if you stop enroute saving the car battery. 

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When I got my F10 the dealer had to add the fridge/charge wires but I think my G30 came from the factory with them already installed.

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Its all installed now, here’s a few pictures with some part numbers incase they are of use to anyone:

 

88NocjH.jpg

 

There aren’t any part numbers for the pins in my fingers there, you need to find them from a spare socket, helpful dealer or ask @535i Andrew ! 
 

These they connected to:

QFlomdF.jpg
 

They crimp on:

H7545np.jpg
 

Thats the towbar end, follow @535i Andrew links I added back up this post for retractable towbars. 
 

For the car end here’s the fuse board again:

 

FPnuNNA.jpg

 

Big fuse 220 is main power (though it still actually goes off when the car goes to sleep). 
 

Small fuse 218 is only powered when the engine is running. 
 


 

dmsU2HU.jpg

 

That’s a connector for the big fuse…

 

jj9Smda.jpg
 

… it goes into the connector behind fuse 220

 

BDlMaaj.jpg
 

Thats the connector for the small fuse, it goes in the back of 218. (You could probably find a big fuse connector with the wire attached like this one if you looked.)

 

jReMHMn.jpg
 

Thats a ground connector. 
 

Use as your see fit! 

 

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