It's shown on a Golf TDI with xenon HID lights but other cars with halogen lights should be the same. The original writeup and pictures are from JTwGTI with additional pics by ksing44, many thanks to both!
NOTE: This article does not apply to the mk6 Jetta since it uses lowline electronics and the mk4 style headlight switch.
This procedure does not apply to the 2010 mk5 VW Jetta or mk5-mk6 Sportwagen (Golf wagon, JSW, or GSW). In those cases, installing the euroswitch is straight plug-play, see 1000q: VW mk5 euro switch install. On the mk6 and newer, you have to run a single wire to the central electric module (CECM) for the parking lights to work correctly. The reason the sportwagen is different is because it's still based off the mk5 with some mk6 updates.
The euroswitch has 3 main positions and 2 for the foglights: allows all lights to be off, the parking
lights to be on, or headlights on. When the parking lights or headlights
are on, you can turn the front foglights on or the front and rear foglights on
(rear fogs not equipped in North America). These are shown below.
Below is a short video explaining the differences.
Off position: no lights at all - the DRL light on the dashboard is off if
you disabled it.
Below left is the parking position: small parking lights, side markers, and
are on. Below right is with the foglights on. You pull the switch
towards you to turn the foglights on.
Here's a closeup of the parking lights:
Headlights on position with foglights on. You can shut the fogs off by
pushing the switch forward.
Disclaimer: disabling the daytime running lights may not be legal where you live. Any and all modifications you do are at your own risk and the consequences for you or any third part are your full responsibility. See the TOS Agreement for the full legal disclaimer. Here is an animated gif of an older car showing the same thing. If you wish to retrofit the rain sensor (required for auto position to work), see 1000q: rain-light sensor retrofit.
1 European spec headlight switch VW#: 3c8 941 431 qx sh (3C8941431QXSH)
VW repair wire (PN: 000979009E)
Metal pick (straight or curved)
VAG-COM / VCDS cable from ross tech
DVOM (optional to test pins)
Plug in the VCDS cable
and start the software. Click on " 09-central electrics" (This
is the CECM). Caution - I've found that VCDS won't connect to a Golf TDI
if the doors are locked. If your VCDS won't connect on any 2010 model, unlock all the doors and try again.
It was very frustrating and I don't know why it's like that but others have also
Then click on "coding" and then "long coding helper".
Once in the helper you need to uncheck 3 boxes (every module may be slightly
different - use the numbers that show up in your long coding helper. Do
not copy the numbers shown in these examples!) There are worded something
like this: DRL switch installed, Separate DRL installed, and DRL. Click
the checkbox and it changes the code. An example is below.
Save and exit the module. If it worked, confirm that the DRL are off and that green "DRL" symbol on your dash is off with the headlight switch in the "O" position (off).
Install your European headlight switch. To remove your stock headlight switch, in the 'Off position - O', push the dial in (forward) until it stops.
Then turn the dial clockwise towards the 'On' position. You will feel a click, then just pull the switch
out. Disconnect the harness from the switch. On the right side of the harness there is a small tab. Push the tab in and pull the harness off.
Pull a little excess wiring out of the dash so you have something to work with.
Once the harness is off, you will notice that the third slot from the right is
empty (assuming you're holding it with the tab to the right). That is slot #3.
To confirm, look in the back of the headlight switch where the harness was. You will see numbering from 1-5 and the 6-10 for the two rows.
The row on the left, 3rd pin from the bottom is pin 3. It's the same on the European switch.
Test your Euro switch to be sure that pin #3 is for the parking lights, or take my word for it. Dana @ Ross Tech has already worked out the pins for both the HL switch and the connector in the CECM. You can use a voltmeter to double check this by putting the switch in the parking light position (=><=) and checking the resistance between pins 3 and 8. It should be null. The pin assignments on the European HL switch are:
8 & 9 = Constant in off position (DRL/TFL)
8 & 3 = Parking
8 & 1 = On
8 & 5 = Fog Ft.
8 & 7 = Fog Rear
Next, expose the 52 pin connector at the CECM. This is a PITA because of access. Move your drivers seat all the way back and locate the footwell light. Disconnect the harness (pulls right out) and unscrew the single torx screw (T-20) that anchors it to the dash.
Above the footwell light you will see the CECM with 3 large connectors on it. The black one to the left is where the parking light pin is located.
To get the connector off, pull the white plastic level over the connector. This holds it to the CECM.
The harness then will pull straight out. To access the pins the harness needs to be disassembled. First remove the outer shell with the white latch on it. There are 2 small tabs that you need to push in to remove the core that has all the wires going into it. This is the tab location on the shell:
This is what it looks like when you start to pull the shell off (notice the tabs towards the bottom of the photo):
This is the outer shell completely removed:
Once the outer shell is off you will have to split the plug and harness in half. It has a joint down the center, almost like a dovetail, and the two halves just slide apart, shown below left. You may have to cut a little of the fabric tape around the wire loom to have enough slack to split it. Find the slot for pin #19. This is for the parking light input signal. The numbers are imprinted just above the bottom edge. Slot #19 indicated below:
Connect pin #3 on the HL switch with pin #19 on the 52 pin CECM harness. Take your yellow VW repair wire and snake it through the hole in the dash where the HL switch was and send it down to the CECM area. This takes some time and a good light. Here is your wire:
Pry the headlight switch plug cover up. Try to pull the ear tabs out to avoid breaking them.
Once the wire is snaked through, simply push one end into the headlight switch harness at slot #3 and tape it to the preexisting wires so that you don't pull it out while working at the other end. Reinsert the harness back into the headlight switch. Here is the new wire taped to the others. When done, push the plug cover back down to lock them in place.
Now push the other end of the wire into slot #19 on the CECM harness. Reassemble the 52 pin connector, tape the yellow wire to the existing wire loom, and then push the harness back into the CECM. Slide the white latch back and that locks it into place. Here is the connector back in place:
Test it out. Push the new euro headlight switch into the dash. Once the ignition is on the parking position (=<>=) lights up green with the dial in ALL positions:
Note: the DRL option on the MFD screen may not do anything once your euroswitch is installed.
If you have more questions about installing a Euroswitch on a 2010+ VW Jetta TDI or Golf, please post a follow up to this post in the myturbodiesel.com forums or search the site below: