In European markets, the Golf (and most other vehicles on the road) have fitted as standard 55W bulbs. These can be upgraded to Xenon Halogen bulbs or even have their wattage increased to 100W.
However, fitting a HID conversion gives you nearly 3 times more light output (it's quite stunning actually) and they only consume 35W of power.
If you follow these instructions, you can do the upgrade in less than an hour and you don't even have to remove the headlights.
The kit I used was this one:

The most important thing to do when you open these kits is to find the installation manual that looks like this:

And then throw it in the bin!!! It's absolutely useless.
Fitting the kit is very straight forward, you only have to drill two holes in the plastic covers, grind a washer and replace 4 spade (faston) connectors from male to female... and that's it!
What's In The Kit
The important thing to remember when ordering is that the kit has to be one for a Mk5 Golf. This is because of two reasons:
- The original lamp is held in place by a bayonet fitting, an adapter is needed to replace this to get onto the 12V lamp connections.
- The Golf has a comfort ECU which monitors the currents consumed by each lamp. The HID draws less current, so the comfort ECU will flag it up as an error on the dashboard and, in some cases, switch the lamp off.
The kit will have all these things inside:

There are two ballasts

And there are the bits specific to fitment on a VW Golf Mk5:

You can see that there are two special adapters to hold the HID lamps in place and also to retrieve the 12V lamp connections:

There are two "error correctors" (which are load resistors) which can be easily connected into the loop.
Installing the Kit
Right hand and left hand references to the car follow the standard way of describing things, that is they are from the driver's perspective from within the car. Therefore when I refer to the right-hand lamp, I am referring to the lamp that is on the same side as the driver on right-hand drive cars.
Remove the twist-on covers from the back of the driving lights. These are large covers that are fairly easily accessed. The headlight main beam lamps have a smaller rubber cover, these do not need to be touched.

Carefully give the bulb a twist anticlockwise and it will come out like so:

You can see from the following picture that new adapter mimics the original bulb holder.

Next you need a hole saw. I used a 28mm saw but this was slightly too big, a 26mm one would have been better.

You need to drill one hole per cover to allow the HID cables to pass through to the outside.

Here the following picture shows the cable assembly complete with its gromit next to the newly drilled access cap...

This is how the assembly looks once put together: IMPORTANT: Note that the 12V bulb supply connects to the bulb adapter. The standard leads come with MALE Spade (Faston) terminals, supplied in the kit are 4 FEMALE spade terminals; these need to be crimped and soldered in place of the MALE terminals...

This is a close-up of the adapter for the right-hand headlight. NOTE: The polarity is important here, with the words "TOP" at the physical top, the +ve (positive or red) 12V terminal is the one closest to the centre of the car. Therefore the -ve (negative or black) is the terminal nearest the outside wing.
Also note that the lug on the HID H7 bulb must fit into the corresponding slot on the adapter. It is not a very good fit and will move when you install the adapter into place. You just have to be careful.
It's also worth noting that the adapter needs quite a bit of force to engage its electrical terminals into the corresponding terminals in the reflector housing.....

This is a picture of the HID lamp installed into the right-hand headlight. Note the red wire is the one nearest the car's centre....

This is the corresponding left-hand lamp installed, again note that the red lead is the one nearest the centre of the car....

Once the cables are installed, turn on your ignition switch and also turn on the dipped beam. Check that there is voltage present and it's the correct polarity.....

Next, we want to mount the ballasts. This is easy, undo one of the bolts that help hold the wing on, and grind one edge flat as shown here:

The ballasts fit snuggly on the wing as shown here....

The car showing both ballasts mounted....

That's it!
Andy.
11th February 2008