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Discussion Starter #1 (Edited)
Fog lights on w/ DRL mod

This tutorial is base on the great write up of @mad2clam. The differences are:
- this is easier(takes 30 mins), no need to wire through firewall, no need to take off steering wheel column cover, less wiring work and it's all done at the fuse box under the hood.
- this is NOT an independent fog mod. The fog will turn on and stay on when the DRL leds are on. You can't turn it off manually when headlights are off. That applies to daytime driving and driving with parking lights. Only when headlights are on, the fogs can be controlled by the fog switch on the steering wheel.
- check out this demo video to make sure this is what you wanted before you decide to proceed.



Daytime Running Fog Lights Guide(2014 Mazda3):

After going through the service manual and looking at how FBCM works I noticed we can actually locate the necessary wires needed for daytime running fogs. See graphs below.
service-manual.jpg
Looks like all we need to do is to have DRL turn on the fogs and we will use a relay to achieve that:
circuit-design-drl+fog.jpg

What you'll need
- some wires, spade connectors and a wire stripper/cutter/crimper tool
- electrical tape and scissors
- 1 x standard relay (4 or 5 prong)
- 3 x quick splice wire taps and pliers

Now let's get to work.
Pop the hood, disconnect the battery negative, take off the cover for the fuse box, pop the FBCM off and get to the connectors:
FBCM.JPG
Locate the two wires we will need (brown is DRL, pink is fog relay ground):
locate the wires.JPG
Use your own wires to tap into these wires(I used 16 gauge stranded):
tapped-2.jpg
Put the FBCM back in the slot and wire up the relay according to the drawing:
finished-1.jpg
I used the same kind of wire taps to connect the two ground wires together(87 and 85) and tied it down to the closest bolt on the body. Put the cover back on and tape the loose wire.
finished-2.jpg

That's it you're done!
IMG_1323.JPG
 

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I just tried this and the fogs come on with the drl but you can't turn it off with the control. I can't turn it off when the headlight is on or off. I followed the instruction.
 

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Discussion Starter #3 (Edited)
I just tried this and the fogs come on with the drl but you can't turn it off with the control. I can't turn it off when the headlight is on or off. I followed the instruction.
That's very strange. If everything is connected correctly, the fog lights should only turn on with the DRL, and DRL goes off when headlights are on. Then the fog lights will only be controlled by the fog light switch on the stalk.

Can you check if the fog lights ONLY turn on with DRL? For example if you put the car in neutral, engage and disengage the handbrake the fog lights will turn off and on?

If you turn on your high beam when headlights are on, does the fog lights turn off?

Is your car 2014 or 15? Halogen or HID?
 

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2014 with hid. Everything works as you describes. But when you have the headlights off you can't control the foglight with the foglight switch. So the foglight is on all the time when the headlight is off. And I did not know that our drl turns off when the headlight come on.
 

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Discussion Starter #5
2014 with hid. Everything works as you describes. But when you have the headlights off you can't control the foglight with the foglight switch. So the foglight is on all the time when the headlight is off. And I did not know that our drl turns off when the headlight come on.
Yea that's exactly what this mod does. Sorry I wasn't clear on the first post and this is not what you wanted. I made it more clear now. You can reverse this mod by just unplugging the relay, get rid of the ground wire, and tape and tug the two wires coming out of the FBCM back in the slot :-(
 

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This is a good write up. I like it alot. I'm going to run the wire that comes off the drl to a switch inside the car so that I can operate it manually. I just need to find a way to run a wire through the firewall.
 

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Awesome write up! I wasn't brave enough to pop off the FBCM myself.

@Iceman04503, I used a spoke from one of my bikes to poke a hole through the rubber grommet that is just above and to the left of the brake pedal where all the wires from the fuse box under the hood comes into the cabin. Then I taped my wire to the spoke and pulled it through the firewall. Hope this helps.
 

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They only work with the headlights on low beam.
 

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Thanks, very informative. Is this the only way to run independent fogs? I wish we could manually control on/off fogs.
 

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Discussion Starter #11

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Do the fogs work with brights on too with this mod?
 

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Hi all,

Someone who knows where the fog switch give an input on the FBCM. I don't have wiring diagram from the stop start module to FBCM.
 

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Sorry for bumping but I didn't see any post confirming if this works on the non-HID models.


Yes! I just did this exact mod to my 2015 S Touring. I recommend using a pair of H11 LED bulbs for the fog lights because it looks great! Also, pull a 15A fuse labeled "HID R / DRL / 15A" It's located above the set of 4 light blue relays inside the fuse box.. Doing so will disable the ugly high beam DRL on both sides.
 

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@g-hood, I was wondering where you got a copy of the service manual showing the wiring diagrams. I have a few mods I would like to do myself and I am trying to find this online.

Thanks
 

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Discussion Starter #20
@g-hood, I was wondering where you got a copy of the service manual showing the wiring diagrams. I have a few mods I would like to do myself and I am trying to find this online.

Thanks
Hi there. the wiring diagrams are in the service manual pin on this forum. Let me know if you can't find them.
 
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