The car shown is a Jetta TDI but other cars are similar. Audi A3 TDI already have a "euroswitch". For 2010-11 VW Golf, use the procedure for mk6 cars since VW changed the electronics. See 1000q: euroswitch install in mk6 Golf for details. The 2010 sportwagen and 2010 Jetta use the mk5 part but it's possible your car doesn't have the trigger wirer for the parking lights. If it doesn't have the trigger for the parking light you have to add one using the procedure in the mk6 Golf writeup.
The example car has retrofitted OEM HID headlights but halogen light cars function the same. The car also has retrofitted front foglights. If your car doesn't have foglights, obviously the foglight switch won't work. Your car must be equipped with rear foglights for the rear foglight position on the switch to do anything. Rear fogs are a bright red light on the left rear taillight for use in fog. Never use them in clear conditions because it will blind other drivers and wash out your rear brake light and turn signal. You may have noticed it on European cars on the road and it's extremely annoying. I wouldn't bother retrofitting them since the hazard flashers can also increase visibility in fog.
Installation is straight plug-play but it will not affect the DRL. DRL is a separate function that must changed through VCDS. To disable the DRL or use the foglights as DRL, see 1000q: foglights or DRL disable. I set the DRL off on the headlights but turned on DRL as foglights since it increases visibility to other cars. However, to use a euroswitch you must completely disable DRL.
The euroswitch has 3 main positions and 2 for the foglights. Below is a
night picture of the parking light position (w/fogs off and DRL disabled) if you
can't see it in the pictures below. Below is a video giving some more
explanations on what a euro switch is.
-Off position: no lights at all. Again, DRL is a separate function and they're on whenever the parking brake is off. In the example below I had fogs set as DRL so the DRL light on the dashboard is on and the fogs are on.
-Auto: if you have the rain light sensor, this turns the headlights on when it's dark. See 1000q: how to add the rain-light sensor if you want this function.
-Parking lights on (front parking light under the main beam, orange side
markers, and rear taillights). In these 2 pictures the foglight switch is
off. In the right picture, the euro switch does nothing because the DRL
fogs are active. If DRL are active (enabled), they always on whenever
except when the
parking brake or headlights are on.
-Parking lights and foglights on. As you can see, the euro switch still
does nothing if DRL are enabled.
-Headlights on (all lights on). Now that all lights are on, the DRL
are off. Front or front+rear fogs can be turned on if equipped.
Here is an animated gif showing how it works. My car didn't have rear fogs so use your imagination.
If you have OEM xenons, it's also possible to have low beam xenons and high beam
halogens on at the same time or high beam xenon and high beam halogen on at the same time
as shown below. See 1000q: 4
headlight mod and 1000q:
OEM HID retrofit for details. Do not have foglights on with the 4
headlight mod because it's illegal to have more than 4 "headlights"
active the front of the car in the US and it focuses your vision too near.
1 European spec headlight switch VW#: 1k0 941 431 aj (1k0941431aj) or compatible switch. All mk5 2005.5-2009 switches should be interchangeable.
1 VCDS cable and software
See 1000q: fogs as DRL or disable DRL for the detailed procedure.
Remove your stock headlight switch. From the off position, push the
dial forward. While holding it forwards, turn it clockwise until it
stops. This will retract some barbs in the switch. Then pull the
switch straight out. Press the plug lock in and remove the plug.
Below is a video with a demonstration with some background info on euro
Plug in the Euroswitch. That's it! If you have more questions about installing a Euroswitch on a 2005, 2006, up to 2009 VW Jetta, Golf, or TDI, please ask in the myturbodiesel.com forums or search the site below. As a final note, the european park light feature can be enabled separately from the euroswitch. See 1000q: park light for more details.