I am also not going to go into great detail about where you should route individual wires, you will find your own way that suits you. I will say that your black four core cable goes through the bulkhead from the engine bay above the pedals where there are other cables already. From there it can go behind the inner sill trims, under the back seat and into the boot in the existing ducting you will find.

If you speak to an auto-electrician or an American car specialist, they will tell you how they solder and shrink seal joints where they cut into the wiring. This is the best method of course, and superior to scotch-locks but you have probably been joining bits of wire to other bits of wire for years so use whatever technique you are happy with.

Four relays, sited in the boot, right hand side of the wheel well, attach the DIN rail to the two captive bolts that stick out there already with 10mm nuts and washers. 

You are using the cars original feeds from the existing lights only to switch relays here. So spurs off your front indicators will switch the relays in the boot to work the back indicators. (And maybe back again to feed the repeaters too if you are not using LED’s), a feed from a front sidelight will feed your fog light switch, and out again to the fog light relay in the boot. A feed from the high level brake light will feed the relay for your new brake lights.  

You need a live next, it doesn’t really matter if it is a battery or ignition live. Straight from the battery is safest I think, not forgetting to run it through a suitable fuse (or fuses according to your taste) first of course.

This battery live will loop and power all your lights and be split and routed through the relays accordingly. The four core cable that runs from front to back is 1) LH indicator, 2) RH indicator, 3) from fog light switch and 4) The new live to feed your new relays in the boot. 

Drill a hole and site the fog lamp switch next to the main headlamp switch or nearby according to your taste. (As long as you can see it from the drivers’ seat.) An example is in the picture on the fog lamp page.  

When you plug in your new Euro back lights, the reverse light and tail lights will work already, there are plugs in the box – with them you can wire up to your new feeds from the relays so they plug on the appropriate lights, they are labelled at the lamp so it is not rocket science. The old brake/indicator light feeds are dealt with by the Euro lights. 

If you use modified lights (as opposed to Euro lights) you will need to put in resistors to slow the indicator flashers down and make the SJB think it is still doing the same job as before (Seek advice from the forums about exactly what and where if you are doing this). 

Wire your relays according to the information on the relay page. Remember to fit your back EMF protection diodes, and be aware that it is imperative they are fitted the correct way round first time. If in doubt, read the diode section again. Take the earth feeds for your relays from the earth tag you will see nearby in the boot. 

Time to take the headlamps out. The front bumper cover needs to come off – its only a few bolts. If you choose to drill the headlights and insert a sidelight rather than use “Angel Eyes”, take them out and do it slowly, upside down with an assistant nearby holding a vacuum cleaner tube next to the bulb hole. If you dont, you will fill the headlight with white plastic swarf (depending where you drill it) which is hard to remove. If you are using ‘Angel Eyes’ you just swap them over. Use the feeds from the original orange side marker light in the front bumper (that you should disconnect anyway for SVA) to power your new sidelights).

Your wing repeaters you can tap straight off your front indicators also; drill the appropriate hole in the wing to accept them. Lose the front amber marker light as described already, and to be on the safe side, take out the pop out rear red side marker units and remove the bulbs for the test. (Different testers take different views on those.) 

And thats about it! The next thing you should do is use the plastic ducting you bought to enclose any wires out of the way, so it looks like a proper job. Tape and/or cable tie all new wires at 300mm intervals anywhere an inspector may see them: boot, under bonnet and above pedals. This is part of the SVA/IVA test so hide and disguise them well, he told me everything should look like the manufacturer did it. So no spaghetti junctions, visible scotch-locks (yuk!) or cock-ups! Everything else other than lights on the S197 Mustang should fly through a UK IVA/SVA test without difficulty at time of writing. 

If you think I have omitted anything or made a mistake here, use the comment box below to say so.

The vast majority of items can be had by mail order, the advertisers on this site will be as good a source as any. The internet tends to make suppliers of this kind of stuff quite competitive as they know you are only a  mouse click away from another supplier who is maybe cheaper than them.

Throughout the articles you may find links to individual suppliers and other resources that I use. So, its time to double check your shopping list before you start. First, the specific parts you will be buying in: 

• A pair of Euro style tail lamps. 
• A pair of Angel Eye head lamps. 
• 4 Omron relays.
• 4 Omron relay bases.
• A short length of DIN rail. 
• A pair of side repeater lights for the front wings. 
• 4 diodes (they come only in packs of ten actually).
• An illuminated fog lamp switch. 
• A length of (black outer) four core suitable cable, probably around 7 meters long. 
• A fuse arrangement of your choice (in line or blade units) 

Thats the big stuff. Other than that, make sure you have some assorted automotive cable in various colours, and you will also need some plastic cable ducting (look under the bonnet if unsure – that stuff) together with the usual assortment of connectors, spades, tape, soldering stuff and cable ties that should be in any automotive toolbox. 

You are now good to go, lets make a start…..

Some people (on a V8) modify the front fog switch wiring to operate the rear fogs. I prefer to tamper with the original wiring as little as possible, so I fit a new switch. (V6 cars do not have a fog switch anyway so you have no choice but to fit a new one in that instance.)

You need an illuminated switch. It should be visible from the driving seat ideally in order to pass a test. I use an after market one and site it near the regular light switch. You can see where I put it from the picture below: 

Such a switch has three terminals.

1) Live in to operate the red LED in the switch, and to feed the switch. (Switch “in” if you like) I take this feed from a front sidelight (some people use a dipped headlamp, but then it tends to go off on main beam). This means the switch will only be powered when the lights are on as it should be. 

2) One terminal is an earth, merely to complete the connection for the  red LED in the switch. Just take one from the under dash metalwork. 

3) The third terminal is the wire that will be fed down to the boot to operate the fog lamp relay that you will fit. (Switch “out” if you prefer.) 

In the boot, you will have a relay you allocated for your fog light. This wire down from the switch will go to terminal 5 on your Omron relays. Refer to the relay page for relay wiring.

When a coil is switched off, a large BACK EMF appears across the coil. This back EMF may be several thousand volts in value, enough to destroy the SJB over time.

To deal with this we fit a diode at the relay, its low resistance short circuits the back EMF voltage and protects the SJB. You can get the diodes from any diode retailer, and they look like this: 

They are referred to as 4001 diode. You may find them listed as 628-9546 or 1N4007-E3 depending where you are looking. 

Observe that one end has a silver stripe on it, that is to ensure you fit it the correct way around. It is imperative they are fitted the correct way round. 

The diode goes between 1 and 5 on your Omron relay bases, bridging between the only feed from the SJB (being the light you have tapped from) and ground – with the black end of the diode going to the Nr 1 ground terminal.  Put another way, black end to earth, silver striped end to switching live from the light you tapped from.

Cover the exposed parts with some sheathing of some kind. I use household earth sheathing (like you might find in a plug socket) to cover the whole exposed diode. I am sure there is a politically correct colour that those who specialise in EU babble will know about – point being, just cover it up somewhow so nothing shorts out on it later on.

Advice from the Mustang forums recommended one type of relay made by Omron. I have tried others but the Omron ones are as cheap as any other and ideal for the purpose, so lets go with those. 

You can get them from anywwhere using the Omron numbers below. I get mine from here. 

The relays themselves are Omron G2R1SN24DC(S). The RS Online number is 353-821. They look like this: 

They plug into some special bases, which are also available from RS Online – they look like this: 

The Omron number is P2RF05E, the RS Online number is 353-944. Having plugged the relays into the bases, they slide on a metal rail in order that they can be fixed in the boot where you will site them. RS Online also stocks this, it is called DIN rail, and the RS Online number is: 424-131. That stuff looks like this:

When you come to wire up the relays, remember to fit your EMF protection diodes – this is critical. The relays have five terminals on the bases, this is how they wire up.

The relays are labelled thus: 

1 (-) 
5 (+)
4 (11)
2 (12)
3 (14) 

And they wire up like this: 

1 – to earth
3 – the live from the battery. 
4 – the new feed to the particular new light in question.
5 – the input from the source light you are tapping from; the switching wire if you like.
2 – redundant in this application. 

Therefore, the EMF protection diode goes between 1 and 5, bridging between the only feed from the SJB and ground – with the black end of the diode going to the Nr 1 ground terminal.

This is a zip file containing several PDF documents. They were supplied to me straight from a very helpful Ford dealer in the USA. Hell, lets give him a plug here: Andy Shaw Ford in North Carolina.

This file is hosted on our own servers so is completely safe to download.

Download link is here: Click Here To Download

The SJB is a sensitive piece of equipment with low tolerances for overload. A new one is a few hundred quid so you don’t want to blow yours. This is the item that the specialists pay most attention to when doing a light conversion. The name of the game is fooling it to make it think it is doing exactly the same job, and powering the same bulbs as before.

No significantly greater loads on any existing circuits is your aim. This is why you do not just link your back lights off your front ones, or a few months later you need a new SJB. This is what the relays you will be using are for, the existing circuits will switch the relays and the actual power will come from elsewhere thus bypassing the SJB.

Switching relays and powering LED repeater lamps is about the only load you will be drawing from the wiring that comes from the SJB. These loads are minimal enough that it won’t notice.

If you see a car with it’s indicators stuck on or exhibiting some other odd behaviour with the lights, then chances are that the SJB is knackered and a cowboy did the light conversion.