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Barboots 03-23-2014 09:18 AM

MY14 DIY Trailer Socket Wiring
MY14 towbar wiring can be spliced in pretty easily. Here's some pictures and information to assist you get the job started.

Trim removal is fairly normal going. At the least you will need the left side boot interior trim off. Refer to this link for general trim removal guidance if it doesn't come naturally:
- and -
Source was located at the base of the left D pillar in the boot. There's a large grey connector which can be unclipped from the body to provide a bit of working length. Note the trailer earth connection on the amplifier bracket bolt.
Source was located just around corner from the tail light behind the bumper and was chosen entirely due to the elevation of the exterior splice. I used a pick tool to push a hole through the ventilation flap's outer frame and ran the wiring back into the boot behind the sub. You could also drill and grommet behind the tail light itself, however it is double skinned here and can be a PITA as a result. Anyway, once inside run behind the spare tyre shroud to the previously photographed location.
RIGHT INDICATOR (alternative)
Source is under the vehicle towards the right side of the boot, and where you will probably have to source the right indicator if you don't want to remove the bumper, or drill behind the tail light... or simply think my method was obsessive or just crap.
Source was located under the sub, on top of the right back wheel in the boot. Not many people bother wiring this in, but there it is if you want to do it by the book. Run across the inside rear of the vehicle with the right indicator.

Red = Stop = White/Brown
Yellow = Left = White/Green
Brown = Tail = White/Grey
Green = Right = White/Yellow
Black = Reverse = White/Lime
White = Earth = Bodywork

Once all wires are in the left rear corner, you can choose one of several methods to route them out. As I still had the bumper off I punched a hole in the grommet located on the lower left corner of the car and then ran along the back of the towbar. Apologies... I forgot to take a picture. You could also go through the floor, which might be best if you tapped the right indicator underneath as per the "alternative" method.
PIN ORIENTATION (flat 7 pin)
Courtesy Narva... they also have all other standards detailed here:

There's obviously several methods you could adopt to run in trailer wiring. I'm not saying that this is in any way the best, it's simply how I did mine.


BobT 03-23-2014 06:46 PM

Re: MY14 DIY Trailer Socket Wiring
Nice splicing job. I'm glad you used solder and heatshrink rather than scotcklocs and tape like the auto sparkies like to use. Have you tried glued heatshrink? It's great for weatherproofing stuff like trailer wiring.

Barboots 03-23-2014 08:21 PM

Thanks Bob, but I've got to admit that I didn't use heatshrink... I don't cut the original wiring so it simply can't be put on. The reason behind this is that the cut must shorten the original wire length, which can then result in stress on the joint. Glue filled heatshrink is great though... I'd definitely have used it if it were possible to get it over the exposed work.

My splicing method is as follows:

I run a very sharp knife extremely lightly around the insulation... twice, about 5mm apart. I then bend the wire just a little bit and slice very shallow between these two circumferential cuts to just expose the wire. Usually, you can now pick off the entire bit of insulation between the two cuts, leaving 5mm of exposed copper with no broken strands and no insulation dags to contaminate the solder joint.

I strip around 10mm from the end of the wire being spliced and wrap it around the 5mm of exposed copper, aligning the end of its insulation with one of the ends of the cut out bit of the existing wire. If there is a surplus from the 10mm strip it should be trimmed, and make sure there are no copper strands sticking up from the joint area.

The joint is then soldered using a 60W iron having a 3mm wedge tip, or a gas equivalent. If you overheat the solder it will follow the iron up as you remove it, leaving a spike. Either remove the solder by tapping it away while heated, or using solder wick, or a sucker. Otherwise file the spike off... it's important to get rid of it.

For interior wiring, I just wrap with electrical tape. That said there's tape and there's useless black shit on a roll. I like 3M and Nitto is good too. Stay out of SuperCheap people!

For exterior splices where you don't want to break the original wiring, self-amalgamating tape is a good solution for waterproofing. I was out of the stuff and wanted to finish, so the one exterior splice has some non-acetic cure silicone smeared onto the exposed wire and once it skinned up I taped it. To be balanced, it's worth pointing out that a good soldering job does a lot to stop moisture wicking up the wires. That and choice of location are the key.

Again, there are several ways to do a good job splicing in wires... this is my standard M.O.


Salmo 07-26-2014 02:03 AM

Re: MY14 DIY Trailer Socket Wiring
Steve, thanks very much for the info and pics.
Got to go fishing tomorrow, but next weekend I'll finish it off.
Thanks again.

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Salmo 07-26-2014 04:22 AM

Re: MY14 DIY Trailer Socket Wiring
I did notice that the dealer just took out the tail lights and connected the tow plug from there, and didn't need to enter the boot space.

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Barboots 07-26-2014 05:20 AM

Re: MY14 DIY Trailer Socket Wiring
I try to do everything on the dry side of the bodywork Steve. Force of habit...

Barboots 08-23-2014 09:37 AM

Having just had the car replaced and bought a new van, I had to revisit and expand on my trailer wiring. The van obviously requires a recharge feed, so brought forward wiring some fat power into the boot which I also needed to do the right thing by my fridge. Additionally, there was Al-Ko ESC and Brake-Safe breakaway power to be installed. I also wanted to interface the van camera with the U-Connect for reversing duties. So I busted out the trim tools and removed the plastics from the entire boot, left D pillar and right along the right hand sill... oh, plus the bumper and rear wheel arch trims. The latter are a pig to remove, and this time I found reaching behind the guard liner you could squeeze the bright orange clips and push them out of the bodywork.

Battery connection as per previous posters. I had intentions to not use the terminal clamp stud, but the main stud is in a bad spot and fitting the lug was a problem. It's quite tight in this corner and you can expect a bit of frustration getting your cable and split tube around the front of the battery. I was tempted to run it over the top or back, but it would have made my fusing messy.

Fusing, mounted on a piece of 6mm HDPE sheet jammed in place. The self resetting circuit breaker is for the brake controller... personally I don't like them, but you don't want a momentary fault taking out your trailer brakes permanently. I still need to cover the terminals... I'll probably use Liquid Electrical Tape as I have further in the next image. The fused B+ cable runs around the back of the battery, as there is no height to spare over the top if you want to refit the battery box lid unmodified.

A mostly finalised work in progress of the main distribution point, though my car fridge wiring is still to go in. Fortunately this area at the base on the subwoofer is quite protected, yet still relatively accessible. Once I'm happy with how the van responds to the wiring I'll do a little tidy up. Note the Liquid Electrical Tape on the studs of my de-VSR'd isolator (it's now just a passive solenoid). Liquid Electrical Tape is a bit less convenient than a rubber boot, but you can get 100% coverage, even on the edges of the crimp terminals which sometimes stick out. The 100A fuse is to protect the van recharge feed individually to the whole rear feed which is fused at 150A in the battery box.

The cable run takes a bit of an arc to avoid stressing the cables where they pass through the floor. Fortunately there is heaps of room in this cavity. A few stick-on cable tie pads hold it in place to ensure it doesn't drum against the floor. There really wasn't anywhere the 25mm2 / 3B&S cable was even slightly difficult to run, except where it runs under the driver's seat into the battery box. I think any increase in diameter might have pushed the friendship though... especially with split tube over it.

The penetration from inside to outside the vehicle is via one of the plastic plugs in the boot floor. I drilled it out a bit to have a look, then decided I'd get everything through there and removed it totally. It just needs to be gently prised off the floor, so you can probably avoid mangling yours. My cable loom was pretty tight in the factory pressed hole, however the metal edge was partly rounded... and with a bit more rounding and some Sikaflex, I'm not worried about chafing or water ingress. I won't run split tube through penetrations, as you can't seal it... so attention to application of the adhesive sealant is vital to prevent insulation damage. A cable gland or four would be a professional alternative if you like drilling lots of holes in your vehicle bodywork, however I don't even like cutting the unseen boot floor sound deadening!

The towbar now has a second tab welded on to provide a mounting location for the two Anderson plugs and the reverse camera socket (not yet bracketed). The van actually "requires" three ignition switched supplies. One for battery recharge, one for Brake Safe breakaway power and one for the Al-Ko ESC (grey 50A, 12 Pin and red 50A respectively). I think it's retarded and was tempted to rationalise it on the van side, but with the van wiring disappearing into the chassis and bodywork I gave in and did what I was told. Note I do appreciate that disconnecting the ESC may be valid in rough conditions, but doing so by leaving the Anderson hanging out is a fairly average solution. Most caravan electricals seem to be...

The following pic is of the reverse camera / U-Connect wiring hack. An ignition feed is run through a 2A fuse, which powers the camera and also runs to the reed switch contacts in the Narva 12 Pin switched lid trailer socket. When opened, the 12V feed returns from the socket and triggers a small DPDT relay board... which breaks the car's reverse cam out of circuit and switches in the caravan's camera in its place. The wires to break/tap are the green brown and green orange, being signal and signal ground respectively. The shield circuit does not get modified. These are tape loomed into their own bundle within the main boot door loom. When you look you'll get what I mean... it's the thin, taped bundle in the top of the picture. You can also see that the remainder of the loom has been deviated to the right to stop it pushing the connections apart.

The board is enclosed in heatshrink now... it just squeezed in. If the location for the tap perplexes you, it minimises the run for the caravan wiring and is also an area where there's a bit of working room in the factory loom. Inserting the relay board means the loom is slightly shortened, so it's important to be able to "borrow" that length without placing tension on the wiring.

One outstanding job is to also deactivate the reverse sensors when the lid of the trailer socket is open. Yes... I could push the dash button, but then what would I do with my spare time? Actually, it's honestly that I forget to turn them back on. I inadvertently hit the garage door as a result of waiting for the beep rather than trusting my judgement. Anyway, I've ID'd the correct wires to work on for a simple power down of the reverse sensor supply... I just want to try to finesse it so the Service Parksense message and chime don't occur.

Oh, as an aside... this time around I found a better way to route in the right indicator for the trailer light wiring. Just drill a small hole in the plastic bumper retainer and use a bit of Sikaflex to prevent water ingress. The wire can then be run through the large grommet behind the subwoofer.


Salmo 09-03-2014 03:11 AM

MY14 DIY Trailer Socket Wiring
Today I installed 2 small led lights on the rear to come on with the reversing lights, with a switch to turn them off if not required. They work great.
BUT now the passive lock/unlock is not working !!
Could somebody remind which 2 buttons on the dash need to be pushed for a minor reset.
I now get the service message showing in the speedo

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Barboots 09-03-2014 03:26 AM

Re: MY14 DIY Trailer Socket Wiring
Don't know if a U-Connect reset is the answer here Salmo... I'd be lifting the negative connection from the battery. To answer your question though, a soft reset is by holding both round push buttons down (mute and browse/enter). The harder reset is available by holding down the passenger side hot and cold (red & blue) buttons.

Where did you grab the reverse signal from? Was it a full 12v, or more like 8v?


Salmo 09-03-2014 03:30 AM

Re: MY14 DIY Trailer Socket Wiring
I grabbed the power from the lime/white wire in the boot near the sub-woofer and then connected to the battery (under the seat) using a fused relay. Earthed in the boot also.

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Barboots 09-03-2014 03:39 AM

Re: MY14 DIY Trailer Socket Wiring
Sounds fine mate. Did you disconnect the passive entry sensor when you removed the spare tyre shroud? Maybe it's not connected properly?

The new lighting is otherwise working OK and activates with reverse??

Barboots 09-03-2014 03:42 AM

Re: MY14 DIY Trailer Socket Wiring
Does disconnecting the lime/white wire from your relay clear the fault? An ignition cycle is probably all that is required based on my experiences freaking out subsystems by disconnecting them, etc.

I can send you my mobile number by PM if you want.


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