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Lighting Forum
Angel Eyes, DDEs, lighted rings, Clear Turn Signals, LEDs, Xenon, HID, or Bi-Xenon. If it lights up and you want to discuss it, post here!

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Old 04-12-2012, 05:27 PM   #1
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Join Date: Aug 2011
Location: pa
Posts: 142
My Ride: 01 325i
Automatic Fog Light Tutorial

I tried following a tutorial on how to do it but they had their wiring color/scheme wrong so I thought I'd do my own tutorial for anyone that wants it. Some pictures/words are taken from other tutorials.

Purpose: Fog light turns on when you turn key into accessory position. Fog lights will always be on (unless you put a switch).

Remove glove box (unscrew 4 screw from two plates underneath glove box, undo two plastic pins on each side of the glove box. They hold glove box from falling to floor inside glove box, unlatch and pull towards you).
Remove plastic shield behind glove box (6 screw then pull towards you)

To make things easier and to provide more working area, I removed the 2 zip ties that secure the massive wiring section to a bracket. One tie was mounted towards the rear of glove box section, and the other zip tie secured the wires right on top of the white grid/box.

Hardest step: Remove white grid assembly (don't' know what it's actually called but you'll know it when you see it. It's a ***** to get off but she'll come. There is (1) screw that secures the bottom part of the grid to the car. Remove this first and working with the clips/tabs much easier.

There are 2 clips located towards the top on each side. The one on the right will require you to push a bunch of wires to the side to see it. The white grid tabs need to be pushed away from you (towards the front of the car).

You have exposed a row of relays. One of them is a different color than the others (orange instead of green in my case but that may differ for you. The fog light relay is always different from the other relays though, at least according to my shop manual). Verify that this relay is the fog relay by touching it while turning on the fogs. You should feel it "click".

Relays going from left to right
A/C relay
Secondary air pump relay
Fuel pump relay (green)
A/C relay (green)
Fog light relay (orange)
Horn relay (green)

Relay up close

Look at the back of the relay port, there should be 5 wires coming from it (4 positions with 1 position having 2 wires)

If you did not detach all the other wires and have pushed the back towards you so you are viewing it upside-down. Take the wire that is located at the TOP (yellow/grey), cut it. Take the wire coming from the relay and wire that to the RED/WHITE wire of the A/C relay/Secondary air pump relay/Fuel pump relay (first green relay on the left)

Take the other yellow/grey wire and tape it. This wire will always output 9v until you press the FOG light button on LCM then it will output 12v. You can wire it to a relay for another project if you want to control your project using the FOG light button on LCM. Other wise the FOG light button on LCM is useless.

If you want more control of whether or not the fog light should be turned on, simply add a on/off switch between the yellow/grey and red/white wire.

Fog light indicator will NEVER BE TURNED ON FROM NOW ON as the fog lights will always be turned on when you put it into accessory

RED/WHITE wire of the A/C relay/Secondary air pump relay/Fuel pump relay (first green relay on the left) is wired to accessory port
RED/YELLOW wire of FOG relay is constant 12v
YELLOW/GREY wire coming from LCM is 9v constant until FOG light switch on LCM is pressed then it switches to 12v
Mods completed:
Dynavin clone install
Rear camera install
Alarm install
Eurotray with DIY micro/mini/ipod charging cable mod

Mods in progress:
OEM flashlight upgrade mod

Last edited by hoang031; 04-12-2012 at 05:32 PM.
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Old 04-16-2012, 08:46 PM   #2
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Join Date: Nov 2010
Location: Rockland county, NY
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My Ride: 04 M56,LC 100,RX300
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Thank you very much for the DIY.

I wanted my fogs to stay on all the time so i added a HID harness/relay and connected the remote wire with accessory wire. Basically the difference is that you hacked the original relay and i hacked the universal hid relay.
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