Headlight switch wiring help, new switch seems different

[mkmskm]

A previous owner replaced the headlight toggle switch with an American style 3 position pull under the dash. I bought a replacement switch and I have the wiring diagram but its not making sense. On the incorrect switch there were 3 wires connected - blue to power, white/black for the running lights and green for headlights. Under the dash I can see the brown and black wires taped off not connected to anything. The wiring diagram shows the switch with posts H for the light blue and Brown wires, V for black, L for white/black and I for green. My switch from Vick's doesn't have an I, its got D instead. I is there but there is no spade on the swtich. How does this hook up and what does the black wire do? Brown it looks like goes to the dimmer switch but my headlights dimmed with the old setup without the brown wire. Another really ignorant question because I've never seen a Fiat wiring correctly - what is the positioning of the switch? Is down off, middle running lights and up headlights? In looking at the switch I can't come up with a positing like the incorrect switch where in one setting it would send power to the running lights and then in the next position to both running and headlights.

[baltobernie]

Do the headlights and all the other lights work correctly? If so, I'd leave the pull-out switch alone. The PO may have performed his own version of "brown wire surgery" by powering the lights independently of the ignition switch. If you install the OE Fiat switch (up is Off, BTW) into a modified circuit, you may experience other problems, including an exciting short-circuit.

[mkmskm]

Yes all of the other lights work. I had to connect the flasher unit when I first got the car to get the turn signals and the hazard lights to work. The lights didn't work until the key was turned on even with the pull out switch so I don't think the ignition switch is bypassed. The light blue wire is what is providing the power and from my diagram that is coming from the ignition switch. The black wire from the diagram looks like its going to the alternator. I would assume on the Fiat switch that the down position would have to give power to 2 spades, one for the headlight (green) and one for the parking (white/black) wires and then middle position would power one spade for just the parking lights but using my ohm meter to check what works for the switch positions that doesn't make sense.

[mkmskm]

Well I connected up all of the wires except the brown one to the original type light switch and the lights work just like as described in the manual. Now I just have to figure out why I would need the brown wire that looks like its part of the dimming circuit even though my lights dim fine.