Electrical wiring question-Lights - BMDUBYA
Please advise.
Nissan Almera 2002: The front fog/driving light glass has smashed, Nissan want £80 for the full unit which I'm loathed to pay, so off I went to Halfords and found a set of fog lights, 55w halogen bulbs with 2 LED's in both lights for only £30, so I'm thinking brilliant. I checked the fog light bulb on both my car and the new lights and both are 55w, so now I'm thinking I can just swap over the unit and use the existing factory fitted wiring and switch on my car, would I be correct in thinking that I can do this? I assume I would simply adjust the existing connections by using a splitter or such like therefore I would not destroy the existing connections. Now the second question, whilst studying the wiring diagram it appears that the LED's a re wired into the sidelights which I assume are a different wattage i.,e. not 55w, so I was wondering how I could wire the LED's up so that they come on with when I switch the fog lights on, I'm thinking that I cannot simply wire together the live to/from the halogen as the halogen bulb is 55w but I am sure the LED's will be less?

The NEW fog lights come with a switch but I dont want to use this as I want to keep everything tidy and use all the existing wiring and switches so to summarise, my questions are as follows.
1. Can I simply replace the units and wire up the halogen bubls still use the existing wiring as both old and new fog light bulbs are 55w?
2. How do I reduce the watts to the LED's so that the LED lights come on when the main fog lights are switched on?

Hope this makes sense. Thanks in advance chaps.
Electrical wiring question-Lights - Hamsafar
Don't worry about the watts for your application, because something taking less watts will not overload anything, and will only take what it needs, unlike voltage, it can't be 'forced' to take watts or amps, as long as everything is 12v (which it will be)
The LED will have a resistor built-in so that it can take 12v instead of the usual 3v or so.
BTW resistors are usually well under 1W, so are negligible.
If it was me, I'd keep your car's wiring intact, and cut the wires off the old fogs to make an adaptor. But without looking at everything it's hard to say what's for best.
Electrical wiring question-Lights - BMDUBYA
Ashok thanks for that, I was worried that I may blow the LEDs but from what you are saying, I won't, is that correct? If so then cool I'll get the new fog lights from Halfords, and as you say I'll make the connections fit and keep the existing wiring in tact. Thanks.
Electrical wiring question-Lights - BMDUBYA
OK sorry to be a bit stupid but I just want to confirm that I can take the live thats feeding the Halogen bulb and feed the LED with that as well without blowing anything? Thanks again.
Electrical wiring question-Lights - Bill Payer
That's correct - but there seems little point in connected the LED if that's what you're going to do - you won't be able to see them when the 55W halogen foglamp bulbs are lit up!
The idea of the LED's (I guess) is so they can be connected to the sidelights and look 'cool'.

The wiring is relatively easy - have you considered the mounting of these lights - presumeably the brackets etc will be completely different to the original Nissan units?
Electrical wiring question-Lights - BMDUBYA
In the box included wiht the fog lights is a relay, obviousley I wont be using this if I use the existing wiring, also I assume there will also be a relay somewhere in the car for the existing lights, but can someone explain what the relay does/is for?

Bill thanks very much for that, I guess you're right about the LED's, the reason I have these particular lights in mind is because of there shape, I think they would not look too much out of place, but I thought it would be a shame not to wire up the LED's. In terms of mounting them, thats something that I need to look at, I'm sure that something can be manufactured.

Electrical wiring question-Lights - Deryck Tintagel
In this case the relay is simply a high current switch. The current drawn by 55W fog lights is something around 4.5A at 12V, so the two would draw 9A. To take this current the wiring to the dash switch woulkd have to be quite heavy in both physical weight and gauge, and the switch itself would be necessarily big to do the job.

The relay coil, on the other hand, will draw something like 0.1A which allows a compact, low current switch on the dash and smaller gauge (cheaper) wiring to the front of the car. The relay would ideally be placed at the front of the car near the foglights to reduce the length of the heavy (expensive) wiring. Some cars have the relay in the under-dash fusebox for convenience for fusing the lighting circuits and will still need heavy wiring forward but it is a compromise for manufacture.
Electrical wiring question-Lights - BMDUBYA
Many thanks to everyone. Apologies to the mods if this should be in the technical. {Now moved - obviously! DD}

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