If you want to use an OEM style wire harness you must have a highline central electric module (CECM) or else the car computer can't know if you have foglights or not. If you want to install OEM HID headlights (see 1000q: VW HID swap for details) and want to use high beams as xenon, you must also have a highline CECM.
The alternative is to install foglights that work off an relayed wire harness. This uses a relay from the headlight switch to turn the foglights on and off. Here are a few mirrored .pdf installation tips for relayed wire foglight harness, do not use these files if you are using an OEM style wire harness: VW retrofit harness , ECS tuning retrofit harness, DIY Jetta foglight retrofit harness
The difference is that OEM style foglight wiring can be used as DRL and is slightly cleaner. To see how to use OEM style foglights as DRL, see 1000q: foglight as DRL.
I ended up not buying a euroswitch because I never use foglights anyways - I only wanted foglights as DRL. Below are part numbers, for the euroswitches. The "coming home" switch has an additional slot that leaves the headlights and courtesy lights on for a set time (you can adjust it) after you lock the car or when you unlock the car. Your car must have the coming home capability to use this feature, you can't just buy the switch.
1 ross tech VCDS cable and a computer
foglights - note: some used 9006 bulb sockets and some used H7 bulb sockets
foglight wire harness - note: some used 9006 bulb sockets and some used H7 bulb sockets
North American headlight switch with foglight VW#
euroswitch with foglight VW# 1k0 941 431 c kos , from redline motorworks,
euroswitch with foglight and coming home VW#1k0 941 431 aj reh
3x screws: VW# n 090 294 1
3x screw inserts: VW# n 905 353 01
2x foglight grilles:
-left: VW# 1k0 853 665 e 9b9
-right: VW# 1k0 853 666 e 9b9
First see if you have a highline CECM. If you don't, you must either buy one or use an relayed wire harness to install foglights. Plug the VCDS into the OBD2 port and start the software/turn the car key to "on". Below are some screenshots.
Click on "central electric".
Click on "coding". You'll see the top screen in the below picture.
Click on "long coding helper" and you'll bring up the bottom screen in the below picture. If you are installing the foglights now, change the coding. If you are just checking for a highline CECM, just look at the check boxes. When you check off the boxes the long coding helper changes the numbers for you. The long coding is #1, the long string of yellow numbers at the top.
If you see the checkbox for Copy/paste it into the previous screen where it says "new coding". Click "Do it!" to enter the new code. If it's saved then it says coding accepted. If it's not saved or invalid it will not say that the coding has been accepted. Always take screenshots before changing the coding!
The pink arrows are pointing at the
checkbox to enable OEM foglights and bixenon headlights. If you click on these and the coding is accepted, you have a highline central
electrics control module. If you don't have the checkboxes or the coding is
not accepted, you don't have a highline central electrics control module.
If you're just testing to see if the code is accepted, unclick the checkboxes
for anything you don't have before exiting the software. If you're
installing foglights now, leave the checkbox for "Front Fog Lights
installed" checked, exit, click "Do it!", and make sure the code
Remove the foglight grilles. There's a single phillips screw (yellow
arrow). There is a tab at the far corner (opposite phillips screw) and
some clips at the top. Try to pull it down a little while rotating it out
(the tab holds it in the bumper). See the below pics for more views.
Transfer the chrome trim to the new grille w/hole for the foglight by releasing the hooks on the backside while pulling
Route the foglight wire harness through the firewall gasket. Poke a small hole and you can push the wire through. A leak that far back is unlikely, especially since the rubber will have some pressure to seal it, but you can use any silicone gasketmaker to seal the hole fully.
convenient ground indicated below for the wiring harness. You have to remove the battery
Inside the car, remove the trim under the steering column (2x T20 torx
screws). Also disconnect the footwell light and obd2 plug.
Slide the 2 red lock levers on the CECM to the side (yellow arrow below) to release the plugs. Remove the plugs. The plugs have short, stiff wiring, so it's pretty difficult to get them mixed up. Plugs A and D are outlined. You can also see "A, B, C," etc. on the
On plugs A and D, pry the pink lock out (yellow arrow below) by about 2 millimeters to release the pins. Then insert the right foglight wire pin into Plug A, pin #4. Looking at the plug end (not the end with the wires), #2 has a yellow wire with blue stripe, #3 has a white wire with violet stripe, #6 has a black wire with green stripe. An illustration is below. After the pin is in place, press the pink lock in to lock the pins.
Repeat with the left foglight pin. Insert it in pin #2 on Plug D.
Verify the wiring for your specific model and year in your factory service manual wiring diagrams; your car may be different!
Below are some markings on the oem style wire harness I purchased. Stecker
is German for plug. Verify them with a multimeter.
Put all the plugs back in the CECM and slide the red lever to lock all the plugs. Replace the plastic cover under the steering column.
Press 3x plastic screw inserts into the bumper (yellow arrows below).
Securely zip-tie the foglight wire harness to route it to the foglight
location. You don't need to remove the bumper for access but if you choose
to, see 1000q: bumper removal for tips.
Near the upper right side of the picture you can also see the screw hole for the
tow eye "hook". If you never need a tow, screw the tow eye into
If you haven't yet activated foglights through VCDS, do it now. Refer
to the above steps.
Pictured below left is a regular headlight switch from a North American car
with foglights. (It's actually from a mk4 car but same thing). To
the right is a euroswitch. This lets you turn on the parking lights and rear foglamps (if
installed). The DRL must be disabled for the parking lights to come on
separately. See 1000q: foglight-DRL
disable or 1000q: Jetta DRL
function for more details. Personally, I would leave the DRL as fogs
and get a regular headlight switch so that they foglights can still be used at
To install a new headlight switch, first remove the headlight switch. From the off
position, press the handle part (not the round trim) forward, hold, and turn
clockwise. Then pull it straight out. Below is a demo video with
some more details about Euroswitches.
Release the plug. The plug also has a small latch on the side.
Release it to expose the pins. Insert the trigger wire into pin 5.
The slots are labeled.
Remove the two torx screws holding the plastic panel and disconnect the obd2
port and footwell light.
Release the plugs on the CECM by sliding the red lock handle to the side. Remove plug E. They are labeled. Unlock the plug cover and slide out the plug end out of the cover as shown below right.
Insert the other end of the trigger wire to pin 6 on plug E on the CECM.
The rest of installation is the reverse of removal.
Did this foglight retrofit work OK on your Jetta or Golf, Rabbit? Feel free to comment on where the article could be improved by posting in the Volkswagen TDI forum.