Easy Mod: Turn on Fog Lights without headlights
#1
Rennlist Member
Thread Starter
Easy DRL Mod: Turn on Fog Lights without headlights
NO GUARANTEES, PERFORM THIS MODIFICATION AT YOUR OWN RISK
I wanted to use my fogs as DRLs, but occasionally wanted to be able to switch them off. After much studying of the wiring diagrams, I developed a mod so the Fog Light switch works without the headlights being turned on. This mod is done to the wiring behind the fog light switch and rear defroster switch. You do have to remove the radio to access this wiring. (I was installing a new radio, so I had easy access.)
Attached 4-page pdf (link below photo) has full details.
Now the fog light switch will work whenever the ignition key is on.
For DRL use, just leave the fog light switch pulled to the "on" position, and fogs will come on automatically every time you start the car.
I did this on my '95 C4, it works great.
(Note- a separate circuit turns the fog lights off when the headlight high beams are on, if you also want to defeat that, details are in this old thread.)
If your fog lights are scratched and discolored, a source now sells separate lenses. It's a bit of work to refinish the housing internals and replace the lenses, but it's worth it. Details in this recent thread.
BTW, I tried several LED replacement H3 bulbs, they were all a total joke.
I wanted to use my fogs as DRLs, but occasionally wanted to be able to switch them off. After much studying of the wiring diagrams, I developed a mod so the Fog Light switch works without the headlights being turned on. This mod is done to the wiring behind the fog light switch and rear defroster switch. You do have to remove the radio to access this wiring. (I was installing a new radio, so I had easy access.)
Attached 4-page pdf (link below photo) has full details.
Now the fog light switch will work whenever the ignition key is on.
For DRL use, just leave the fog light switch pulled to the "on" position, and fogs will come on automatically every time you start the car.
I did this on my '95 C4, it works great.
(Note- a separate circuit turns the fog lights off when the headlight high beams are on, if you also want to defeat that, details are in this old thread.)
If your fog lights are scratched and discolored, a source now sells separate lenses. It's a bit of work to refinish the housing internals and replace the lenses, but it's worth it. Details in this recent thread.
BTW, I tried several LED replacement H3 bulbs, they were all a total joke.
Last edited by centerpunch; 05-24-2019 at 11:09 AM.
The following 8 users liked this post by centerpunch:
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#3
Rennlist Member
Great information. My 993 was initially a USA car, then imported later to CAN. Fog lights work separately as DRL. Now I know what to look for in terms of how it was possibly modified for CAN. Thanks.
#7
Rennlist Member
Thread Starter
Great to hear someone is using the info I put together.
I am a DRL believer, especially in silver cars that can blend in with the surroundings.
I am a DRL believer, especially in silver cars that can blend in with the surroundings.
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#9
Drifting
#10
Rennlist Member
Thread Starter
As I said earlier, I can't imagine anyone knowing or caring in the US.
These days virtually all cars have daytime running lights, and these are a good substitute for those...
These days virtually all cars have daytime running lights, and these are a good substitute for those...
#11
Rennlist Member
Here in the US there are plenty of BMW, MB, Audi and others that drive with their rear fogs on at nite and they haven't a clue.
My dad once told a lady at a gas station driving an Audi, her rear fog light was on, her reply: "oh I don't know what all those buttons are for so I just turn them all on".
Harold
My dad once told a lady at a gas station driving an Audi, her rear fog light was on, her reply: "oh I don't know what all those buttons are for so I just turn them all on".
Harold
#13
Great mod! If I ever pull my radio I'll think about doing that mod. 100% of the time when I drive any car I turn on the headlights and taillights as it makes me way more visable and hopefully will save me from people hitting my car or pulling out in front of me. 😀
Also my two Volvos have a setting to automatically turn on the headlights and taillights to always on day and night whenever driving. I wish more cars had that setting and not just a nighttime sensor setting as I see too many cars driving during dark and/or rainy conditions with all of their lights off because they've set their car to autosensing lights and their car doesn't turn their lights on correctly yet their inside dash lights are on so the driver thinks their headlights and taillights are on when they're not! 😞
Also my two Volvos have a setting to automatically turn on the headlights and taillights to always on day and night whenever driving. I wish more cars had that setting and not just a nighttime sensor setting as I see too many cars driving during dark and/or rainy conditions with all of their lights off because they've set their car to autosensing lights and their car doesn't turn their lights on correctly yet their inside dash lights are on so the driver thinks their headlights and taillights are on when they're not! 😞
Last edited by RockstarBruski; 05-21-2023 at 10:11 AM.
#14
Rennlist Member
Thread Starter
Eight years later it’s possible that there are now H3 LED bulbs that are ok, might make sense to try them.
Although the normal halogen bulbs work fine and last a long time.
Although the normal halogen bulbs work fine and last a long time.