Disclaimer: I do not condone the inactivation of daytime running lights (DRLs). If you do this DIY and inactivate your DRLs, you will likely crash and be killed or severely injured. Also, I do not believe that you should do any work on your VW. All work should be done by a VW dealership and a certified VW tech.
Okay, this DIY will allow you to turn off your DRLs and run that tiny light under your low beam with or without your fogs. People have their own reasons for wanting to inactivate DRLs so please, let's not turn this into a "why shut off the DRLs, they are a safety feature" thread. The goal is to run a parking light trigger wire from the HL switch to the Central Electric Control Module (CECM) under the drivers side dash.
Another thing is that my car has xenons and so I can't speak to this working on halogen equipped cars, though I suspect it will. Also I chose to use a non-auto Euro switch because I don't have a light sensor and don't plan to retrofit one (if its even possible).
What you need:
1. European spec HL switch (PN: 3C8941431QXSH)
2. VW repair wire (PN: 000979009E)
3. T-20 torx
5. Metal pick (straight or curved)
6. Electrical tape
7. VAG-COM / VCDS
8. DVOM (optional to test pins)
Step 1- First you need to disable your DRLs using VCDS. For xenon-equipped cars: module 09-central electrics > coding > long coding helper. Once in the helper you need to uncheck 3 boxes (wording may be a little different than what I have here - my memory is poor):
1. DRL switch installed
2. Separate DRL installed
Once you do this, confirm that the DRLs are off and that green "DRL" symbol on your dash is off with the headlight switch in the "O" position (off).
Step 2- Install your European HL switch. To remove your stock HL switch do the following:
1. In the 'Off position - O' depress the dial until it stops;
2. Turn dial clockwise towards the 'On' position;
3. You will feel a click, then just pull the switch out;
Now you need to 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 and holding it with the tab to the right, you will notice that the third slot from the right is empty. That is slot #3. To confirm, look in the back of the HL 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 is the same on the European switch.
Step 3- 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. I used a voltmeter to double check but I trust her for sure. To do this put the switch in the parking light position (=<> and check the resistance between pins 3 and 8. Should be null. The pin assignments on the European HL switch are (from Dana):
8 & 9 = Constant in off position (DRL/TFL)
8 & 3 = Parking
8 & 1 = On
8 & 5 = Fog Ft.
8 & 7 = Fog Rear
Step 4- 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 wire harness in half. It has a joint down the center, almost like a dovetail, and the two halves just slide apart. You may have to cut a little of the fabric tape around the wire loom to have enough slack to split the harness. Here are the two sides once split apart:
Step 5- Find the slot for pin #19. This is for the parking light input signal. The numbers are imprinted just above the bottom edge. Here is slot #19:
Step 6- 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:
Once the wire is snaked through, simply push one end into the HL 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 HL switch. Here is the new wire taped to the others:
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:
Step 7- Test it out. Push the new HL switch into the dash. Once the ignition is on the parking position (= < > lights up green with the dial in ALL positions:
Here are the lighting configurations with pics:
1. Off position (O) - no lights
2. Parking position (= < > - small parking lights, side markers, and tails
3. Parking position + fogs - above + fogs
4. Low beam position - small parking lights, side markers, tails, low beams
5. Low beam + fog - above + fogs
That's it. Good luck and let me know if I can help in any way. (x3 once you finish)
Modified by JTwGTI at 5:49 PM 1-16-2010