Electrical & Audio Guides
Fitting Front Fog Lights
You will need:
- Fog lights (I used rectangular Ring ones from Halfords, but any will do the job.)
- Lots of wire (The wire that feeds power to the fog lights must be capable of handling 10 amps at least - each fog light draws approx 4.5 amps with a 55 watt bulb.)
- 30 amp 4 terminal "automotive" relay.
Drill 2 6mm holes in the bodywork just underneath the bumper, one either side of the oval opening. Don't try to mount the lights on the bumper as they will wobble far too much to be of any use. When bolting the brackets to the car use some large bumper washers as the metal is quite thin and this will limit the movement and wobble when going over bumps, it will also stop the weight of the lights bending the front valence, which (as I discovered) can happen!
(There are regulations as to the distance from the ground, distance from sides of the car, distance between lights etc, which I have written down somewhere, but they seem to have disappeared, when I find them I will add them to this, as people keep pestering me to know what they are!)
When wiring up fog lights you are required by law to use an illuminated switch, I originally used an Escort switch mounted in my centre console but after getting pulled over numerous times for forgetting to switch the lights off I decided to fit a more visible switch. There was a proper front fog light switch for the Fiesta dash board which had the right symbol pointing the right way on a black background instead of a red one, but I have only ever seen one of these switches. So the next best thing to do is to modify a rear fog light switch.
If you get an old switch then the symbol will slide out of it's position without taking the whole switch apart and then you can slide it back in the other way up. If you get a new switch then you will need to take the bottom off the switch first. This is done by gently releasing the clips that hold it on, and then sliding it out of the main switch - take care not to drop or loose any of the metal bits inside! Push the symbol out from the inside so that it pops out the front of the switch and then simply push it back in the opposite way up. Now clip the bottom back onto the switch, making sure that all the bits are still there!
Remove the blanking plate from the switch section to the right of the instrument cluster and wire in the new switch, you can do this one of three ways. I used computer power connectors (the ones that connect to hard drives etc) but you can use terminal block or, to make a really professional job, solder the wires together. Connect the grey/yellow wire to the grey/yellow wire on the rear fog light switch and the brown wire to any earth point (might as well connect it to the brown wire on the rear switch). The remaining wire connects to the switching coil of the relay (terminal 86), I mounted my relay on the bulkhead under the bonnet so this last wire needed to be run out through the dash and bulkhead (take the wire out through the grommet where the existing loom comes into the car).
To wire up the relay you will need a few meters of cable that can cope with at least 10 amps. The lights each draw approx 4.5 amps when on, so a combined current of just over 9 amps, with be required. It is easier (and cheaper) to use the same cable for the whole job rather than use 10 amp cable to feed power to the relay and then 5 amp cable to feed power to the lights, but you can do it this way if you like. You need a fuse in the power for the relay, this must have a rating of 10 amps, don't be tempted to use a different value just because you have one lying around... fuses are far cheaper than fire damage! You can get simple inline fuses holders from any car accessory shop, or if you are planning on building all of my circuits then you may like to consider getting a 5 way fuse box, these are available from Maplin Electronics for a small and very reasonable amount, and they take the standard blade type fuses (added bonus!). Right now to finish wiring the relay. You should already have the wire from the switch connected to terminal 86, so connect terminal 85. to any existing ground point (top of suspension turrets is the standard ground point). Now run a 10 amp wire from the fuse to terminal 30 on the relay and connect the other side of the fuse to the battery. Now connect two wires to terminal 87 and connect the other end of each of these wires to each of the fog lights (connect to the wire on the back of the bulb). Finally you will need to connect the other terminal in each fog light to ground, so run another piece of wire (5 or 10 amp) back up to the existing ground points on the car.
Relay wiring at a glance:
- Terminal 87 - to the fog lights
- Terminal 86 - to the new fog light switch
- Terminal 85 - to a grounding point
- Terminal 30 - to the fuse
Because we connected the grey/yellow wire on the switch to the same wire on the existing rear fog light switch, the front fogs should only work when you have the lights on. However, they do not rely on the rear fog lights being on and so remember to switch them off when no longer needed. Don't drive around on the public roads with them on when it's not foggy, simply because it looks cool, it's not big or cleaver and blinds oncoming drivers, the Police also have the power to issue an "on the spot" £20 fine!!
A word of advice when bolting the fog lights into the brackets: If the brackets don't have fairly big serrations on them then it's a good idea to use serrated washers, otherwise you will find that with time the lights slowly start to point at the floor, you will be forever cursing when you suddenly need them and all they do is light up the way for your sump!!!
One final thing I have done with the aid of one bit of wire and a diode is to connect my fogs to my main beam, so that they go on and off with that as well. This is handy because it lights up the area in front of the car that is normally missed out by the main head lights. To do this, get a diode (1N4007 is readily available and does the job fine), and a bit of wire. Now using some wire connect the end of the diode with the stripe (cathode) to the wire that goes from the new switch to the new fog light relay, and then using some more wire connect the other end of the diode (anode) to the main beam switch wire (use scotchloks or something similar). The fogs will now switch on and off with the main beam, the point of the diode is simply to stop the main beam coming on when you switch the fog lights on.
Job done!
