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Fog light bulb question?

Old 05-04-10, 06:35 PM
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Fog light bulb question?

I know the bulb type is H3, but when looking for a bulb does it matter how many watts its putting out?

Because im looking at getting yellow halogens but they have 55w and 70w bulbs, is there a difference other than one being brighter that the other?
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Old 05-04-10, 07:16 PM
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I'm guessing it would be like anything else that requires more watts, just putting more of a strain on your electrical system. I'm sure if I'm spreading disinformation I'll be corrected.

You might give this link a shot for a cheaper alternative to our harder to find and more expensive bulbs. I found this link on rx7club but don't remember how or why.

http://www.lexls.com/tutorials/light...onversion.html
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Old 05-04-10, 07:27 PM
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Our cars use H3C bulbs, which unlike the H3, do not ground on the body of the fog lamp housing. The H3C have a separate ground side that goes on the harness that connects to the bulb itself.

That being said, all you need to do to make the H3 bulb work with the current harness is just plug in the one lead on the H3 bulb to the positive side of the harness coming out of the car, and using one of the Phillips screws on the bulb housing, make a small lead wire which connects from the housing into the ground side of the harness, so you essentially complete the circuit.

As far as using higher wattage, there will be a limit to how much the small gauge wires on the car will handle until they start to heat up and potentially melt. I believe the gauge on the car is around 16-14 gauge, so i can assure you, the most you will want to run is around 75w safely. After that you might run into problems. (I used a Wire Gauge Table to find out this number). Some bulbs come in 100W, I would not recommend running them unless you upgrade the wires since you can only run 108W safely on 14 gauge wire up to 20ft. long.
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Old 05-04-10, 07:32 PM
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Originally Posted by jjcobm View Post
Our cars use H3C bulbs, which unlike the H3, do not ground on the body of the fog lamp housing. The H3C have a separate ground side that goes on the harness that connects to the bulb itself.

That being said, all you need to do to make the H3 bulb work with the current harness is just plug in the one lead on the H3 bulb to the positive side of the harness coming out of the car, and using one of the Phillips screws on the bulb housing, make a small lead wire which connects from the housing into the ground side of the harness, so you essentially complete the circuit.

As far as using higher wattage, there will be a limit to how much the small gauge wires on the car will handle until they start to heat up and potentially melt. I believe the gauge on the car is around 16-14 gauge, so i can assure you, the most you will want to run is around 75w safely. After that you might run into problems. (I used a Wire Gauge Table to find out this number). Some bulbs come in 100W, I would not recommend running them unless you upgrade the wires since you can only run 108W safely on 14 gauge wire up to 20ft. long.
+1 for a better answer than me
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Old 05-04-10, 07:46 PM
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ok that makes sense

so pretty much just run a wire from the negative part of the bulb to a screw holding the light housing correct?

and if im going to get a 70watt bulb its safe to use 16-14 gauge wire?
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Old 05-04-10, 09:14 PM
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Originally Posted by lunardeathgod View Post
ok that makes sense

so pretty much just run a wire from the negative part of the bulb to a screw holding the light housing correct?

and if im going to get a 70watt bulb its safe to use 16-14 gauge wire?
Yes, you will be fine as long as the those wires for the fog light wires on the harness are not longer than 25feet, which I am positive they are not.

You will run a wire from the housing (using a screw or someplace so the wire can contact the housing, probably using a soldered butt connector end, or crimped though I prefer you solder the end connector if you can) to the harness that plugged into your old fog bulb, on the negative side. The other wire on the H3 will go to the positive end. You will know you have them backwards if the bulb doesn't light up.

Use the guide posted by JustJeff, it has pictures : )
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