Trueno headlight issue ...

[Red]

Gentlemen, may I present you with a similarly obscure lighting question?

I am the original owner of a US 1985 GTS, so I know my wiring is stock. This model has the pop-up headlights with H6054 (dual-filament rectangular) sealed beams. I've been trying to upgrade the stock beams to a Sylvania-Osram HID system, which is US-DOT street legal unlike most other systems.

It uses an HID low beam, and a separate H3 high beam. In theory, I take the low beam connection from the headlight socket to a power relay, and power up the HID ballasts for my new HID low beams.

And then take the high beam connection from the socket to my high beam.

Toyota, unique in the world, uses a common positive feed for the headlights, and then grounds the high/low beam in order to turn each one on. Except...

It isn't that simple. No matter how I try to make the connections (and Sylvania has assisted marvelously, but they don't know what Toyota has done here) apparently the high and low beam wiring in the car is interconnected. If I power up the low beams, the high beams also come on and stay on--even though the aftermarket bulbs are totally electrically isolated, the only connections being the ones IN THE CAR FROM TOYOTA.

Apparently these cars were deisgned so that when a low beam burns out, instead of that corner going black, the car splits the voltage from the other headlight and makes a part of the high beam filament glow dimly. There's some "voltage divider" in the car's system, ensuring that if a low beam is out--it still gets power from a high beam. And that odd little system means that if I try to "just" connect new beams, the high and low beams all come on and stay on together.

Not good!

I'm about to try doing something very impolite--like disconnecting the high beam switch leads, at the steering wheel, and using that switch to engage a fully separate power line to the high beams. I'd rather not butcher the system that way, but I'm at wit's end.

Where have the evil sorcerers interconnected the high and low beams in this perverse "common positive" headlight system? Does anyone have any idea?