Quote Originally Posted by Dick61 View Post
The problem is not with your indicator/dimmer switch, it is with your wiring loom. You should have high and low beam in the outer two lights and the inner ones should only work on high beam. The set up you have at the moment is that the outers only work on low beam and the inners only on high beam, although you should find that the outers are actually single filament high beam lights. When you use the flasher on the indicator stalk both beams are activated but only while the stalk is pulled back. This is correct whether you have twin or single headlights, to have your lights operating correctly you need to change your outer lights to high/low beam lights and correct the wiring loom to suit. If it doesn't already have one, it is a good idea to fit a relay to operate the highbeams.
You are correct Dick, this taken directly from the HZ Holden Owner Manual and I quote:

"FOUR HEADLAMP SYSTEM"
"Operating the dipper switch alternates the light beams on the outer two headlamps between low and high beam. The inner two headlamps operate only when high beam is selected."

So from that, the outer two headlamps would be double filament and the inners single. Obviously you would have to have the matching wiring loom etc and presumably any other differences between two headlamp models and four headlamp models would be built into the electrical system.