And here's how, for A2s with US-spec aero headlights - the ones that suck
at night.

When I last posted, it was to ask about the best way to wire my new
euro-aero H4 lights. I received one response, advising a permanent
clip-n-crimp. But I didn't want to do that. Here's what I did do.

You need:
1 pair euro-aero headlights (APS, $250 with shipping - bulbs, but no wires)
1 pair stick-on vinyl headlight protectors (from dealer, $40) (if there are
any rocks in your area)
1 pair Bosch 30-amp fused relays (from dealer, $8 apiece)
1 pair Hella US 3-prong to H4 3-prong adapter-pigtails (dealer got them
from Hella, $13 apiece) 

stuff from a department store:
2 10' lengths of 12 gauge wire (use more than 10', less than 20') for power
- red is nice
some other short pieces of wire
bunches of connectors
a few zip-ties

The wiring takes the longest time. Pop off the grille, carefully so as not
to break any of the brittle plastic pieces which can only be fixed by
getting a whole new grille. Remove old headlights, use for paperweights. Or
if you're absolutely, positively sure you won't ever need them again (which
I couldn't say) dispose of them permanently in a vicious manner of your

Cut two lengths of wire to run from your chosen relay location (mine was
between driver's side headlight and the battery) over to the passenger side
light. There is a nice crossmember at top-of-bumper height, handy for
fastening wires to with zip-ties. Cut two much shorter lengths to go right
there from the relay to the driver's side light. Hook these up to your
dual-output relays in pairs. Make some ground wires in the area of your
mounts, hook these to the brown wires of the Hella pigtails. Wire the power
wires so that one relay goes to the white wires (of the pigtails) and the
other goes to the yellow wires. It doesn't matter which relay is which, as
you will see in a moment.

Grind two spade connectors down enough (about half their width) to fit in
the 9004 plug. Hook one to the coil of each relay with some small wire, and
ground the other sides of course. Now two more lengths of your red wire go
from the starter solenoid connection (oh, you want to pop the negative
terminal off the battery first, of course) to the power side of the relays.
Zip ties all over to keep things tidy. I even used zip ties to secure my
relays to two holes already in the area in front of the battery.

Tape over the unused 9004 plug on the passenger side, and put it somewhere
where it won't flop around (more zip ties!). Install your H4 lights,
setting the alignment screws to approximately the same position as your old
lights' screws. Mine are now pointed in slightly from before, but if you
have a fairly well-aligned grille, they will look pretty square in it

Now, having reattached your negative battery terminal, stick one
ground-down connector into the blue-wire terminal of the 9004 plug on the
driver's side, and the other in the white-wire terminal. Make the lights
come on (usually by starting the car and turning them on). Flick back and
forth between high and low beams to see if you need to switch the wires
around in the 9004 plug. I got it right the first time. Hey, 50/50. There
will be a marked difference in the high and low beams - just wait till you
drive at night! If the high beams are truly on when the little blue lights
in the dash indicated they should be, wrap up the plug and wire with some
electrician's tape. You should also have wrapped up the wires on the new
relays before securing them.

Reattach the grille, and go for a night drive with your small Phillips
screwdriver. Adjust alignment as necessary. The beam centers should be
directly in front of the lights, same height above ground and separation,
out to 25 feet or so. I haven't had any complaints from the low beams. And
aren't the high beams great? You have to be careful with them, though.
Because I said so. Don't blind anyone unless they are sitting in front of
you going 10 mph under the speed limit on an uncrowded freeway. Then zap
'em and watch them move over.

Drive safely, now.

Henry Harper
1988 GTI 1.8 16v, 150k, ticket-me red, 2.25" TT cat & stainless cat-back,
Bilstein Sports, K&N, new euro-aero H4s, really wants a sixth gear now