jleidel

I recently went through the fun of converting my 88' S4 from H3 [standard in the US] to H4 lamps. The conversion is easy, but I figured I would post what I learned for others.

First off, handle the lamps with care!

- Parts? H4 Lamps [duh]. I highly recommend going to your local auto store and picking up a set of H4 lamp plugs. Autozone carries them in store for ~$2.50.
Similar to these:
http://www.autozone.com/autozone/acc...er=421807_0_0_

- pop the hood before you remove the three screws on the headlight surrounds. It makes it easier to access inner screw.

- When you clip the wires on the existing H3 style loom, make sure you leave enough length to attach the new plugs. Don't destroy the H3 plugs either.

- Regardless of whether you solder the new plug in or use some sort of wire bridge, use electrical shrink wrap to seal the hot connections. You don't want things to get moist and short...

- if you're using an H4 connector [see above], then remove the lower tab on the rear of the H4 lamp. As scary as this sounds [H4's are not cheap], you don't necessarily need it... and it gets in the way of the plug

- wire the plug correctly! High beam to high beam, low beam to low beam... you don't want to run around in the evening with the high beams blaring by default. Pay attention to the numbers on the rear of the H3 plug that you remove and the numbers on the rear of the H4 lamp. Hmm... they match! This is an easy guide to mating the correct wire to the correct tab on the lamp.

Finally... my childish attempt at a wiring diagram...

Tom. M

I kept the 4th prong on the H4's...and just shaved the "bump" on the bottom of the plug adapter.. lots easier and cheaper to replace. You don't need to remove much plastic to get it to slide up and along the extra prong...

Rob Edwards

Timely thread, I have a pair of H4's to put on the GTS. The wiring diagram (dummies edition) I want to see is one with either 2 or 4 relays to take +12V off the jump post and switched power from the headlight wiring itself, with suggestions on where/how to mount the relays, wire gauge, how to run stuff into the headlamp pods, etc. Y'know, an idiotRobproof version.

Alan

USA S4+ cars use 8" H5 headlights with replacable bulbs called 9004's

ROW (Incl) cars have 8" H4's with 9003 bulbs (or H4 bulbs)

H3's are the single filament bulbs used in the S4+ fog & driving lamps

Yes numbering is confusing...

Alan

Bill Ball

My conversion from 8" H5 to H4 maybe 6 years ago...

http://www.billsworkshop.com/P928S4/h5toh4/h5toh4.htm