difficulty: 2/5
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Introduction
DRL disable is the first step in installing aftermarket HID lights. DRLs are the low beam H7 headlight bulbs run at about half power. HID lights run at half power will damage them so they have to be disabled. This is because HID lights light up like fluorescent lights - they use a ballast/capacitor for initial light up and consume low power after they're warmed up. HIDs should be either on or off and you should never quickly flicker them on-off because it stresses the ballast.
Stock light bulbs are H7. You can safely retrofit DS2 HID bulbs into the stock projector headlight (low beam) because the lens filament depth and projector focus is unchanged. Do not put HID bulbs into the stock high beam because it's a reflector headlight and you'll get lots of glare. Reflector headlights don't have cutoffs and don't throw light down onto the road like a projector lens. They will also produce a poor lighting pattern. NOTE: any non DOT approved headlight is for off road use only!
Also polish the lenses because if they are cloudy or pitted, more light will create more glare. Cloudy headlight lenses can also be the reason why the headlights seem dim. See 1000q: how to polish cloudy headlight lenses for details and reviews of kits.
I do not suggest buying cheap aftermarket headlights because while they look fine from a distance or in pictures, the plastic is brittle and they usually have cheaper than OEM construction. If you buy aftermarket headlights, buy them from an OEM manufacturer like Hella.
The optimal temperature range (color) for most OEM HID lights is 3000-4000k. Too high or low and the light becomes colored or washed out. Some people like blueish lighting but this color stresses the eyes and is annoying to other drivers. Blue headlights can also get you pulled over for illegal headlights. A color range of 3-4000k will look white. If you have a choice recommend a 35w kit because it's much brighter than stock but not as bright as 55w.
While you can install HID lights and ballast as plug-play into the stock wiring, it's suggested to power the ballast from a relay harness directly from the battery. This is a much more stable source for providing energy for the ballast than the stock wiring. If you have any flickering or failed/delayed light-up of the bulbs, this will often solve it. Instead of the stock headlight plug powering the ballast and telling it when to light up, the ballasts are turned on by a relay connected to the stock headlight plug and powered directly from the battery. There should be an inline fuse as well.
Here is an example of a headlight after an HID conversion and polishing the
lens. As long as they are aimed properly they won't blind other drivers.
Parts
HID kit
phillips screwdriver
zipties
silicone caulk or liquid electrical tape
First disable the DRL. Open the driver's side door and pry off the fuse box cover at the end of the
dashboard. Remove the 2x torx screws holding the side of the lower knee
trim panel.
Remove 2 more torx screws in the front of the panel. There are a few
spring clips that may pop out when you pull off the panel, make sure to save
them. Once it's off disconnect the headlight switch, dimmer switch,
and obd2 port plugs.
You can also remove the headlight switch by (in the off position) pushing the
switch part forward, then turning it about 1/8 turn, then pull it straight out.
You can now see the relay panel. Pull relay 173 out. This will disable the DRL. No check engine light will be set. You may be able to reach around and pull the panel without removing the trim.
Remove the rubber cover over the low beam as shown below. The headlight
is out of the car for illustration but you don't need to remove it to install
the kit.
Release and remove the clip holding
the low beams. Put the old bulbs to the side, they can be used as high
beams spares.
Cut a slit into the rubber cover so you can pass the wires through it.
Pass the bulb's plugs through the rubber
cover and plug it into the ballast. See more pics below if you need a pic
of this. You may need to snip or bend the bulb holder a little to fit it
over the plugs. If you are using the relay harness don't snip it.
Below is an example of how it should be wired. The spade connectors go into the original headlight
plugs. When you put the bulb into the socket, the wire on the exterior of
the bulb goes on top.
The rest of installation is the reverse of removal. Make sure the bulbs are flat and locked. Do not touch the bulb with your fingers or get it dirty at all! If the glass gets dirty, wipe it down with a lint free cloth and rubbing alcohol.
Because you slit the rubber cover, put some silicone caulking around the hole to waterproof it. Black liquid electrical tape also works well and should be a better color match. Use double sided tape to stick the ballast anywhere. Make sure the wires won't get caught in the coolant fan or flop around. Use zip ties to secure them.
If you are using a relayed harness (suggested)
Follow the above steps until you are ready to plug the ballast into the bulb wires. Do not snip the bulb holder.
You won't use the spade connectors on the bulb. Carefully slice the
black round rubber gasket to remove the unused spade connector/plug
wires. These will not be used with a relayed harness because the relay
will tell the bulb when to turn on/off.
The disconnected plug below goes to the other ballast for the other
bulb. The 2 spade connectors plug into the stock low beam headlight
plug. When you turn the headlight switch on, the stock low beam plug
activates the relay which ignites the ballasts which turn on the bulbs.
The ballast on the other side won't plug into the stock plug because it's
controlled from the relay, not the other side's headlight plug.
Plug the ballast and bulbs into the relayed harness to test fit
everything. Once you are satisfied, pass the plugs through the rubber
cover as shown below. The bulb holder should fit on without snipping it.
When you put the bulb into the socket, the wire on the exterior of the bulb goes
on top.
Put the spade connector into one of the original headlight plugs. Make
sure it's tight. If not, slightly bend the spade connector so that there's
a good connection. Tape the wires in place so that it can't come
loose. If one of the wires comes loose the low beam headlights will shut
off.
Put the headlight bulb in place on both sides. Make sure it's flat and
locked. Now connect the relayed
harness terminals to the battery under the 10mm nuts.
The rest of installation is the reverse of removal. Don't touch the bulb with your fingers! If you do or the bulb gets dirty/oily, wipe it down with rubbing alcohol on a lint free cloth. Put some silicone caulk around the slits in the rubber low beam covers to waterproof it. Black liquid electrical tape also works well and should be a better color match. When placing the ballasts, clean both surfaces and use double sided padded tape to stick it anywhere.
Here is how I routed mine - below is a test fitting highlighted in blue. I suggest putting the wires under the plastic air snorkel and covers.
Battery through the rubber AC line gasket on
the firewall - next to the air intake box (pass side ballast is there and passes
under the air intake snorkel) - in the front of the car tied to the radiator
support - to the ballast next to
the power steering fluid reservoir. Make sure the wires won't get caught in the coolant fan or flop around.
Use zip ties to secure them. Make sure to shake the wiring to make sure it
won't come loose or rub through.
Looking for recommendations on HID kits? Please ask in the VW TDI forum at myturbodiesel.com.