# Electrical wiring - additional 12v socket



## jampott (Sep 6, 2003)

Bear with me - newbie at car wiring.

I want to wire in an additional 12v socket (hidden inside the front dash) - and rather than splice into existing wires, I'd rather tap into the fuse box directly.

Can someone point me towards what I'd need to buy to accomplish this, and any instructions on how? I'm guessing I just need to wedge some spade connectors into something - either a spare fuse or the one which already holds the 12v sockets...?


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## Naresh (Nov 22, 2004)

There's a link on Wak's webiste explaning how to fit a 12V socket in the boot so you could use those instructions to help you out.

Here's the link:

http://www.wak-tt.com/mods/12vboot/12vboot.htm

It looks like it connects directly to the fusebox so you could use the same principle on your car.


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## garvin (May 7, 2002)

Jampo,

I do this on most of my cars in order to make incorporation of various electrical goodies easier. I am not familiar with the wiring diagram on your particular beast but on most cars there is usually a main fuse box under the bonnet with ~4 main fuses of between 30A and 60A capacity. This then feeds down to the multi fuse box which can be inside the car. I usually take the feed for my auxiliary equipment from the 'live' side of one of these 'main' feeds where it enters the multi-fuse box, usually with a large 'ring' connector rather than a spade connector.

The first thing to decide is whether you want the output to be ignition fused or permanently live ............. or both! This dictates where you take the 'live' feed from.

You also need to decide how many sparately fused circuits you want? If just one then a 'floating' in-line fuse holder is probably OK, but for more then RS do a four way auxiliary fuse box which is ideal - just connect all the spade connectors on one side of the box together and attach the feed to it. You then have four spearately fused outputs on the other side. If a circuit is not used then just don't put a fuse in it so that the 'output' side is not live. The box is quite small so can be located conveniently under the dash but make sure the live feed cable is as short as possible to reduce to a minimum the chances of any inadvertant short circuiting - on a 60A main circuit one doesn't want to catch the car on fire!! Oh, and always make sure the wire used is rated accordingly for the current carried!

I also find a suitable earthing point and attach a multi connector (chocolate) block via a flying lead and ring connector in order to provide a conveniently placed earthing point under the dash.

Most connections are crimped but I also solder them (belt and braces) and use heat shrink sleeving to keep everything neat and tidy and well insulated - all bits and pieces available from RS or Maplins - just need a hairdryer for the heat shrink sleeving ............ or I use a paint stripping heat gun.

All sounds complicated but is, in fact, pretty easy.


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## jampott (Sep 6, 2003)

garvin said:


> Jampo,
> 
> I do this on most of my cars in order to make incorporation of various electrical goodies easier. I am not familiar with the wiring diagram on your particular beast but on most cars there is usually a main fuse box under the bonnet with ~4 main fuses of between 30A and 60A capacity. This then feeds down to the multi fuse box which can be inside the car. I usually take the feed for my auxiliary equipment from the 'live' side of one of these 'main' feeds where it enters the multi-fuse box, usually with a large 'ring' connector rather than a spade connector.
> 
> ...


Sounds easy when you describe it, but I daresay it isn't to someone like me...

Do any of the reasonably local bods fancy doing a "show and tell" session?

Irving at Kneesworth?

The fusebox in the S4 is in the endcap of the dashpanel at the drivers side. Dead easy access, and there is a plenty of space inside there to house what I had in mind (my GPS receiver hidden, plus (maybe) a power lead for a phone charger, which I mount on that side of the steering wheel anyway...)

But doing the electrics? Hmmm I'd be able to do it again if shown, but I need my hand held for the first time...


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## garvin (May 7, 2002)

Jampo,

Does the S4 have the 'bus bars' under the dash like the TT as this is by far the easiest 'tap-off' point for live feeds - both ignition fused and permanent lives - I have my PDA holder, GPS receiver and GPS re-radiating antenna powered from them.


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## Wak (May 6, 2002)

jampott said:


> Bear with me - newbie at car wiring.
> 
> I want to wire in an additional 12v socket (hidden inside the front dash) - and rather than splice into existing wires, I'd rather tap into the fuse box directly.
> 
> Can someone point me towards what I'd need to buy to accomplish this, and any instructions on how? I'm guessing I just need to wedge some spade connectors into something - either a spare fuse or the one which already holds the 12v sockets...?


Tim, are you after a 12v live? or 12V only on when the car is running?

Also are you after a temporary flip open socket? permanent use socket?

I have the temporary Flip








which is wired to the old ashtray loom so is permanent,

My boot socket it wired to a relay so its only live with the ignition.

I also have a flying lead socket up front in the cubby hole which is live for my video recorder charger.

perhaps tell us what you want to plug in , is it permanent and does it need to be on always and why you cant use your existing socket?


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## jampott (Sep 6, 2003)

Wak & Garvin

I want a hidden 12v socket (like a trailing one from Maplins) - so I can plug in a normal phone charger - all hidden inside the dash - rather than an exposed or flip down piece.

I can use my existing 12v scket, but that means trailing a cable to my phone (or GPS) whichever is being powered.

Tapping straight from the fuse box and leaving the GPS receiver hidden in the gap behind the fuse box means hiding EVERYTHING from sight.

I'd prefer it to be a permanently live feed (like the 12v sockets normally are) as my GPS will have a permanent sat-lock - but it really doesn't matter that much either way.

I'm not really sure what a bus bar is. I daresay its wired similar to the other Audi range, but if I looked, all I'd see is a bunch of wires.

I'm pleased to say I managed to plumb in a Dension cradle all by myself, but that really is the limit of my electrical knowledge


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## Chip_iTT (Nov 14, 2003)

Tim,

I have the Maplin's trailing socket hidden under the ashtray inside the console and a second one behind the glove box so that the GPS/PDA can be plugged in. Both are out-of-sight but can only be accessed by removing the appropriate trim. Both are off the busbar (feedpoint) under the drivers side dash on the TT... no doubt there's something similar on the S4... via an inline fuse rated at 5A (figured that was enough for what was needed, the standard cigarette ligher is fused at 16A).

If you want, we could fit this at Kneesworth next Wednesday (we'll need some decent lighting as it'll be getting dark by 8 and its hard enough to see under the dash in daylight). I assume you know how to get behind the dash and have the necessary tools to do so. I'll bring soldering-iron and other 'leccy stuff....

Parts you will need are (all part # are Maplins):

Car Acc Socket 1 off FE42V @ 99p
In-line Fuse holder 1 off DR79L @ 49p
31mm 5A Fuse 1 off GL81C @ Â£1.09 pk/10
Brown equip wire 32/0.2 2m off XR34M @ 39p/m 
Red equip wire 32/0.2 2m off XR36P @ 39p/m

You will also need some spade or eyelet terminals. I dont know what size the fittings are but likely to be 5mm so 1 pack each of JH76H (red spade)and JH78K (blue spade) @ 52p each should do the trick.


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## garvin (May 7, 2002)

jampott said:


> Tapping straight from the fuse box and leaving the GPS receiver hidden in the gap behind the fuse box means hiding EVERYTHING from sight.


It is nice to have everything hidden from sight, but for the GPS receiver it may not be as simple as that. The receiver antenna will need a clear view of the sky, through the windscreen usually. It can see through the plastic of the dash but with degraded performance and, when located to one side of the dash with the metalwork of the front bulkhead, door and 'A' pillar in the way the performace may be somewhat lacking! Before going nap on such a position I would test it out first with 'trailing' leads using the usual cigarette lighter socket.

For a permanent installation don't use a 'flying' cigarette lighter socket if you can get away from it. The plugs invariably come loose at some time and therefore need taping in and are rather bulky. However, if the plug contains the necessary voltage regulation (12V to 5V or whatever) then this may be the simplest way.



jampott said:


> I'd prefer it to be a permanently live feed (like the 12v sockets normally are) as my GPS will have a permanent sat-lock - ....


With modern GPS receivers the 'cold' start 'time to first lock' averages about 50 secs, warm start about 35secs and hot start of around 2 secs. Therefore, there is no real need to have it permanently on - mine is not on all the time - it comes on with the ignition and as long as nobody has picked the car up and moved it without the ignition on then the satnav is up and running within about 10 to 20 secs (enough time to get the required number of satellite locks).



jampott said:


> I'm not really sure what a bus bar is. I daresay its wired similar to the other Audi range, but if I looked, all I'd see is a bunch of wires.


It looks like this on a TT and is located under the driver's side dash:-


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## Chip_iTT (Nov 14, 2003)

garvin said:


> jampott said:
> 
> 
> > Tapping straight from the fuse box and leaving the GPS receiver hidden in the gap behind the fuse box means hiding EVERYTHING from sight.
> ...


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## garvin (May 7, 2002)

Chip_iTT said:


> I agree, my GPS mouse sits on the dash with the wire coming out by the A-pillar but everything else is hidden. Works fine there but wouldn't give reliable results under the dash.


Why not locate it in the OEM position i.e. under the driver's side vent on top of the dash. I have my RA45 GPS re-radiating antenna receiver mounted here, completely out of sight. The other aerial is under the dash mounted close to the system GPS receiver again completely out of sight - works very well too.



Chip_iTT said:


> With most GPS mice this is the only way... The solution, as used on my install, is simply to tape the plug into the socket with some insulating tape!


Yes. I did state this as an option in my earlier post. However, on one installation I have soldered and sleeved flying leads to the necessary 'plug' instead of using a socket.



Chip_iTT said:


> I wonder where you got that pic from Garvin


Yes, 'he' already picked me up on it the first time I used it .......... do you think 'he' charges royalties ............ or am I open to prosecution for copyright infringement :wink:


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## jampott (Sep 6, 2003)

Whoah

Cheers for the help everyone 

Ivring, I'm going to order that list of stuff from Maplin website (assuming it'll take the product codes!) and I'll bring some strong torches to the meet.

The first step (for me) is simply to get something wired in. Exactly where I end up locating it isn't necessarily (?) a problem, as I'm sure it (the trailing socket) can be relocated.

I THINK my GPS will work from that cubby. It certainly works from the coin tray and things like that. Quite a strong signal - but if I knew how to get under the dashboard, I'd mount it there instead.

As an alternative, there is 12v accessory power in the boot as well. Definately could splice off that feed and hide the GPS in the side panel of the car - however, splicing into electrical wires is definately something I'm not going to attempt on my own!

Thanks again for everyone's help and suggestions. I'll buy the bits, and take suggestions from people at Kneesworth for the best location(s) to put things!

BTW Irving - would it be better to fit a DOUBLE trailing socket to give me a spare for later?


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## garvin (May 7, 2002)

Chip_iTT said:


> If you want, we could fit this at Kneesworth next Wednesday ............. I'll bring soldering-iron and other 'leccy stuff....





jampott said:


> Ivring, I'm going to order that list of stuff from Maplin website (assuming it'll take the product codes!) and I'll bring some strong torches to the meet.


Irving, you are a brave man ............... who's bringing the generator to power the soldering iron :wink:

Don't forget to take a digital camera to capture the action. I'd particularly like to see how the FE42V socket should be properly soldered onto the leads by an expert - I have never liked my amateurish efforts with this unit as I find it hard to get a good insulated joint and almost impossible to strain relieve the cable. BTW I usually use household twin core (brown/blue) lighting cable to attach to this sort of socket as it can take quite a load and is fully sheathed.


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## jampott (Sep 6, 2003)

garvin said:


> Chip_iTT said:
> 
> 
> > If you want, we could fit this at Kneesworth next Wednesday ............. I'll bring soldering-iron and other 'leccy stuff....
> ...


Maybe the friendly landlord will let us solder in the pub 

I'll take my camera, but looking unlikely that I'll take the doggies as well. Doggies and trying to work on the car don't really go hand in hand


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## garvin (May 7, 2002)

garvin said:


> Don't forget to take a digital camera to capture the action.





jampott said:


> I'll take my camera .........


Better still, I just might be able to make the meet to witness it in person. I'm in London all day and will have to see if I can organise an early escape ............... as long as nobody minds me 'gatecrashing'


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## Chip_iTT (Nov 14, 2003)

jampott said:


> garvin said:
> 
> 
> > Chip_iTT said:
> ...


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## Chip_iTT (Nov 14, 2003)

garvin said:


> garvin said:
> 
> 
> > Don't forget to take a digital camera to capture the action.
> ...


Not at all, you'll be more than welcome


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## NaughTTy (Jul 9, 2003)

If necessary, and we can plug into the extension lead, I can bring an inspection lamp along if you like.

Maybe someone has an inspection lamp that can be plugged into a cigarette lighter - I know they're available.


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## Chip_iTT (Nov 14, 2003)

NaughTTy said:


> If necessary, and we can plug into the extension lead, I can bring an inspection lamp along if you like.
> 
> Maybe someone has an inspection lamp that can be plugged into a cigarette lighter - I know they're available.


'Cept i wouldnt want to plug into the car I'm working on ideally


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## NaughTTy (Jul 9, 2003)

Chip_iTT said:


> NaughTTy said:
> 
> 
> > If necessary, and we can plug into the extension lead, I can bring an inspection lamp along if you like.
> ...


Yeah - I thought of that - that's why I said "a" cigarette lighter :wink: I'm sure someone won't mind lending another car for that. Then again, we don't know if anyone has one anyway! Should I bring my mains one along?


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## Chip_iTT (Nov 14, 2003)

NaughTTy said:


> Chip_iTT said:
> 
> 
> > NaughTTy said:
> ...


Yes, better than just a torch as gives more of a floodlight.... is yours the sort with a glare shield?


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## NaughTTy (Jul 9, 2003)

It's just a cheap plastic one but has a shield that goes about half way round. It's solid plastic so not much light passes through the shielded area. Should be good enough for working under the dash though


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## jampott (Sep 6, 2003)

I'll bring my camping flourescent, plus a couple of LED torches 

Oh, and Maplins delivered all my bits over the weekend


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## Chip_iTT (Nov 14, 2003)

Thats good Tim... all set for Wednesday then.

Now if you'd like to sign my usual disclaimer.... no need to read the small print*... 

*If it goes wrong its not my fault OK


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## JulienG (Nov 8, 2006)

Chip_iTT said:


> Tim,
> 
> I have the Maplin's trailing socket hidden under the ashtray inside the console and a second one behind the glove box so that the GPS/PDA can be plugged in. Both are out-of-sight but can only be accessed by removing the appropriate trim. Both are off the busbar (feedpoint) under the drivers side dash on the TT... no doubt there's something similar on the S4... via an inline fuse rated at 5A (figured that was enough for what was needed, the standard cigarette ligher is fused at 16A).
> 
> ...


@Chip_iTT
Hi
Where do you locate In-line Fuse holder? 
If that fuse burns, do you have to reach the busbar and to remove the dash under the steering wheel or do you manage to locate them near the fuse box so that it can be accessed via the fuse box pannel?

Regards

Julien


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## zacob1992 (Nov 24, 2016)

> Bear with me - newbie at car wiring.
> 
> I want to best Soft Wiring in an additional 12v socket (hidden inside the front dash) - and rather than splice into existing wires, I'd rather tap into the fuse box directly.
> 
> Can someone point me towards what I'd need to buy to accomplish this, and any instructions on how? I'm guessing I just need to wedge some spade connectors into something - either a spare fuse or the one which already holds the 12v sockets...?


Hello
Bear with me - newbie at car wiring.

I want to wire in an additional 12v socket (hidden inside the front dash) - and rather than splice into existing wires, I'd rather tap into the fuse box directly.

Can someone point me towards what I'd need to buy to accomplish this, and any instructions on how? I'm guessing I just need to wedge some spade connectors into something - either a spare fuse or the one which already holds the 12v sockets...?


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