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Discussion Starter #1 (Edited)
Hey Folks,

I could not find anywhere on this forum a DIY for a Fog light DRL conversion without buying some parts so I wanted to share with the world how this can be done. And illustrate how easy this is which is always a plus :)

Why do this?
As a safety feature on the B5 and B5.5 the headlight low beam bulbs. With these being on 24/7 the bulbs tend to burn out quickly. I have gone thru at least 1-2 sets every year so hoping this will save me a little money too.
In order to keep the safety feature I still wanted lights on all the time so using the fog lights I still keep these benefits.

Plus I think it looks better too with the fog bulbs and no headlights running.

Parts Needed:
HOW TO DO THIS

Step 1:
Remove the fuse box cover to expose the fuse box and some relays

Step 2: Remove both the 398 Relay (we will plug this back in later) and the 173 Relay (DRL Module) to the back left of the fuse box. This allows for some visibility to make this happen

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Step 3: Attach your Add a Fuse to the 1 foot of wire and crimp it. i also heat-shirked it for extra protection but this is optional.
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Step 4: on your add a fuse bend back one of the metal tabs as you can only fit one of the tabs in the wire.
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Step 5: MAKE SURE THE KEY IS REMOVED FROM THE IGNITION BEFORE STARTING THIS STEP! This is where small hands come in handy. Reach back where you removed the 173 relay and insert the tab from the add-a/fuse into the second slot down on the left side (circled in photo).
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Step 6: Attach the end of the 1ft wire to a voltmeter and turn the key to on. You should be reading 12 volts. If you are not then try to insert it into a different tab where the 173 relay was until you get 12 volts. When you turn off the car it should go back to 0 volts (This is the DRL Power) Now you want to tap or secure the Add-a-fuse so it does not come loose over time. I just used some electrical tape to keep it secure.


Step 7: Now we will attach the DRL power wire to the fog light power on the Headlight Selector. Remove the headlight light switch. Follow this if you have never done this before - Light switch removal on B5.5

Step 8: With this removed you will detach the harness from the switch and you take the DRL Power wire and insert it into the harness on position 8 (in my case it is the top most white and yellow wire in my photo). When you do this turn the key to the on position and your fog lights should come on. Turn key to off position and they should shut off.
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Step 9: Tapping into the Fog Light Wire. This step is a little more involved and if you have not tapped into a wire before please research which way you would like to do this. I choose to use the Westinhouse split on this link 2nd section - Fundamentals of Automotive Electrical Connections and Connectors

First you need to strip the cover off the wire to expose the bar wire. You only need to expose 1/2 inch to an inch of wire. Once you do this then you can take a paper clip or a small knife in my case and split the wire apart using the Westinhouse method above. You then put your DRL wire through and wrap it around a few times and finish it off with some electrical tap to make sure the connection does not loosen. Test and ensure that your fog lights come on and off with the car ignition and you are pretty much done.
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Step 10: Re-insert the headlight switch, 398 relay, put on your fuse box cover and enjoy your Fogs as DRLs
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Disclaimer: I assume no responsibilty whatsoever for damages that an end user may inflict upon their vehicles or themselves using information contained herein. Proceed with caution and care when performing modifications to your vehicle. Be advised that making modifications to your vehicle may void your manufacturer's warranty.
 

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Good work. This is technically hardwiring your fogs to be on all of the time correct? Do they turn off when you turn the headlights on? Do they turn off when the handbrake is pulled? If not, (and if you care to bother with it) you need to remove the output wire from the DRL relay plug while keeping the DRL relay in place.

Since I my son and I don't have fogs on the B5 HID, I am looking at putting the city lights as DRL. I have an LED city light setup in the garage (sitting for probably over 10 years).
 

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Discussion Starter #4
Thanks PZ. You are correct this is more then just DRL this is always on which for now I dont mind. Thx for the recommendation I may look into this at some point but will need to map out which pins I need to connect to on the Relay for this to happen.

And that shouldnt be too difficult just need to see if you can tap into some wire in the headlight switch and you dont have to mess running wires thru the firewall. Hope that goes well
 

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2004 B5.5 Variant 1.8T
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One of two things you may want to do is either remove the fog light wire from the headlight plug entirely or add a diode to your DRL tap-in to prevent a back feed situation.

Since the fogs will always be on, there will not be a need to use the fog function on the switch.

I went a different route in that I removed the factory fogs and just installed LED daylights in their place. Since I always drive with the headlight switch (euroswitch only) in the parking lights position, I just pull out once for the re-purposed fog/DRLs to light.
 

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Discussion Starter #6
So what I did was I actually bent back the tab on the headlight switch for the fog so that this will not make a connection and this "should" prevent back feed. But I agree I think i will disconnect it entirely so there is no chance and maybe can re-purpose the headlight switch fog for something else in the future. I do like the look of your LED DRL very clean!

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2004 B5.5 Variant 1.8T
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Good thinking. I hate bending pins on stock harnesses, personally. I don't trust the pin to bend back to normal without breaking if I need to reverse something.
 

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Discussion Starter #8
Ahh right always a risk of breaking it for sure. I’ve done that on my fair share of add a fuses as well. Luckily they are cheap!
 
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