DIY: Fog light mk4 harness wiring diagram

witchcraftz

Veteran Member
Joined
Aug 28, 2011
Location
Vancouver BC
TDI
2015 Golf TDI
I made a clear diagram on how to install fog lights on a MK4. The fog harness I bought came with no instructions and the ones I found were not helpful.

I included a diagram on the top left made by someone else showing the pins on the headlight switch, if you made this and want credit, let me know and I'll add your name. :)

 

turbocharged798

Veteran Member
Joined
May 21, 2009
Location
Ellenville, NY
TDI
99.5 black ALH Jetta;09 Gasser Jetta
While it will work fine with that setup, its not entirely correct as the stock fogs take the power directly from the switch and the relay is there solely to disable the fogs when the high beams are on.
 

brian_e

Veteran Member
Joined
Jul 3, 2004
Location
Farmington NH
TDI
2001 Silver Jetta
I don't know anything about stock fog light wiring but my general preference is for the switch not to carry high current and prefer the relay approach.
 

witchcraftz

Veteran Member
Joined
Aug 28, 2011
Location
Vancouver BC
TDI
2015 Golf TDI
While it will work fine with that setup, its not entirely correct as the stock fogs take the power directly from the switch and the relay is there solely to disable the fogs when the high beams are on.
The stock setup is more complicated and I do not believe the wiring kit is for sale.

This will work using one of the easily available fog wiring kits and you can run it to work with either lower grille fogs or into the OEM headlight plug to run in headlight fogs. :)
 
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glitdi

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Joined
Dec 28, 2009
Location
West Coast Canada
TDI
Tdi asv motor in a mk3 golf, om642 in a wk jeep
Yes there are good quality kits for sale... Also the stock set up is not exactly complicated... its fog lights... What messes people up with the stock fog lights is that there are two sources for control power going into the relay... this is what allows the fog lights to switch off when the high beams are turned on.. the control side of the fog light grounds through the high beam circuit until the high beam circuit is activated.. two sources of power opens the switch...
Once again.. The best fog light harness on the market is here..(also best wiring harnesses for german brand cars) http://www.kufatec.com/shop/en/volkswagen/bora/bora-1j/fog-light-wiring-harness-vw-bora-relaisThe only flaw with it is the fact you use those stupid splicers to get the power source.. other than that its pretty close to perfect...
Op's buy this harnes... dont bother with a hack job... (no offence) Just seen a lot of crappy wiring jobs...
Anyone wanting to add other factory features these guys have a lot of really good wiring harnesses that most anyone can understand and follow..
 
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Intech

Veteran Member
Joined
Jun 25, 2005
Location
S. Central Pa USA
TDI
2003 Jetta GLS, 1999.5 Golf 2 dr
I made a clear diagram on how to install fog lights on a MK4. The fog harness I bought came with no instructions and the ones I found were not helpful.

I included a diagram on the top left made by someone else showing the pins on the headlight switch, if you made this and want credit, let me know and I'll add your name. :)

Good set-up. I have it on my Jetta. I don't want the fogs going off when the high beams come on, and consider fogs, because of their fluting, to be excellent auxiliaries. I've been using that type of arrangement for many years. Specific fog lights give peripheral illumination that you don't get with either low or high beams.
 

emscar

Veteran Member
Joined
Apr 21, 2013
Location
Manchester, NH
TDI
`00 Golf, auto trans
Thanks for posting this Witchcraftz. I`ve got a set of Bosch bumper mount foglamps that i`ve wanted to install an with this diagram i can!
 

WilburBeast

Active member
Joined
Feb 22, 2015
Location
California
TDI
2002 VW Jetta TDI ALH Automatic
Mk4 fog lights

I made a clear diagram on how to install fog lights on a MK4. The fog harness I bought came with no instructions and the ones I found were not helpful.

I included a diagram on the top left made by someone else showing the pins on the headlight switch, if you made this and want credit, let me know and I'll add your name. :)

I just put some fog lights on my mk4 jetta tdi last night just like this. For whatever reason they aren't working. Before I ran the wire from the relay to my headlight switch, I used it on positive terminal of battery to check lights. They lit up and relay clicked like a dream. There are little led bars I put with the fog lights, I connected them accordingly with neg pos and yellow wire syncing them. Wiring/electrical is my weak point but don't see my folly here needhelp! Please pm or post:eek:
 

nokivasara

Veteran Member
Joined
Jan 25, 2008
Location
Sweden @ Lat 61N
TDI
Tiguan 4-motion, Golf mk7
The relays aren't silly when the light switch melts and the car goes up in flames.

That happened to my dads old mk2 Golf and it took the garage with it. I had a mk1 Caddy at the time and took my light switch out and found a bunch of wires that barely had any insulation left. Those were really bad, I'm sure the mk4 setup is better...

EDIT: Oh sorry, didn't read that part where it's stated that the OEM fogs run their power through the switch, in that case adding relays seems less important. I'd add them anyway to run as short power leads as possible for less losses.
 
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romad

Top Post Dawg
Joined
May 27, 2011
Location
Prescott, AZ
TDI
2005 Jetta GLS Wagon "Cranberry"
I just put some fog lights on my mk4 jetta tdi last night just like this. For whatever reason they aren't working. Before I ran the wire from the relay to my headlight switch, I used it on positive terminal of battery to check lights. They lit up and relay clicked like a dream. There are little led bars I put with the fog lights, I connected them accordingly with neg pos and yellow wire syncing them. Wiring/electrical is my weak point but don't see my folly here needhelp! Please pm or post:eek:
Did you replace your non-fog capable NA headlight switch with an OEM Euroswitch?
 

WilburBeast

Active member
Joined
Feb 22, 2015
Location
California
TDI
2002 VW Jetta TDI ALH Automatic
..got it


The wire that came for the relay to the switch was a POS. Gauge was incorrect, swapped it and works fine!:D
 
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