BklynRX7

Hye guys my fog light switch finally arrived today. Now I am unsure how to hook it up i figured i would just run the +/- form the battery into the switch and then back out to the lights. But when i searched to eb sure i see somthing about illiminating the switch and needing a relay. SO has anyone else done this(im sure) and exactly how?

FirstRotaryExp

iTrader: (3)

I have applied a set of foglight/driving lights to my car, purchased the thing at walmart. An illuminated switch, if you dotn have one, can run you about 2-5 bucks depending on what you buy, but it will be just as easy to wire as a non illuminated switch as all you add is a ground wire.

Just follow the instructions supplied with your kit then just go buy a new switch that might be more what your looking for and wire it up the same, find a suitable ground in teh location you mount the switch and youve got illumination. As a referance I placed my switch in my console, next to the security light, though I also turned the panel around so the tray is forward and teh switch is closer to the armrest, thus nearly eliminating my issue with the wires at an extreme angle.

edit: Oh and remember that you do NOT run the negative to teh switch at all. The power wire runs from teh battery, to teh switch, then back out to the lights with the supplied wirign they might have given you had you bought a kit. The ground wires you run separate for the lights to the frame or suitable area within a few feet, bu no longer than 3 feet.

88rxn/a

iTrader: (6)

i thought about tapping into the low beam wire so that they turn off when i hit the high beams, and i wont have to worry about the damn toggle switch when i get out of the car( headlights are off, no power to foglights).... i hate that!!

Icemark

NO that would be incorrect.

There should a fuse and a relay wired in the system. The switch should never do anything more than switch a relay, which switches the lights.

So if you were wiring in a switch, the switch should be connected to parking lights (red/black) on the input and to the relay on its output (then the fog lights would always turn off if the the parking lights were not on). (Note: if you are using the stock Mazda fog light switch, either wire can be used for input and outputs- they are fully reverseable and will work either way).

So the relay would be wired to the battery through a fuse, and switch positive 12+ volts to the lights, while the switch would simply trigger the relay.

Using a standard 12 volt DPST automotive relay, it would be wired as follows:
12 volts from battery through fuse to pin 87 of the relay, 30 of the relay to each of the two fog lights, 85 of the relay to ground/body, and 86 of the relay going to the output of the switch. Input of the switch would come from the parking light wire mentioned above (found at the light switch, Center consol plugs, radio, etc).

This way, if the parking lights are on, you can switch the fog lights on, but if you turn the parking lights off, the fog lights would also turn off, regardless of the fog light switch position, And if you hit something, and bust the lights, instead of every inch of wire melting into a slag heap of copper, the fuse would blow protecting the switch, and wiring (and battery).

Fog lights wired in any way or shape without a relay and a fuse are just a fire waiting to happen.

BklynRX7

COudl i just run the 12v to the battery if im not worried about them turning off with the parking lights?

Icemark

You could wire one end of the switch to 12 volts at the battery instead of to the parking lights, (but I would never every recommend it- too easy to forget and drain your battery down- and in many states it is illegal to operate a vehicle with fog lights on and not parking or headlights on), as well as you still should use the relay and fuse (a fuse should be within 12 inches of the battery of every aftermarket connection to the battery or 12 volt constant lines).

remember most switches (the Mazda OEM fog light switch included) are rated for only 5 amp current. Occasionally you might see a 10 amp rated fuse but that its more uncommon.

But 2 H3 bulbs (standard 55 watt bulbs used in almost all decent fog lights) can draw almost 10 amps peak... you can see how if you didn't use a relay the switch is easily double the rated contacts... leading to fire and meltage. And if you don't have a fuse and relay... and you short the system directly to the switch... well peak power is only limited on how much the wire can take before it melts... 20- 30 amps maybe even 40 amps.... well if you have a wire that can take 20 amps, and a switch that can take 5amps... well which one will melt first???

88rxn/a

iTrader: (6)

if i did this with the proper fuses and such would it be ok?

Icemark

yeah as long as you used a relay, you wouldn't want to overload the already weak headlight circuits

kungfuroy

iTrader: (6)

The attached pic shows how to wire the fog lights up independent of the headlights being on or off. To make the wiring a bit easier for yourself, you could get one of those add a fuse kits.

BklynRX7

^^ well im doing all the wiring with a aftermarket POS amp kit. Its total crap but wire is wire and it includes a 12v wire with built in-line fuse box.