That is, in fact, the drving light switch (PN VVN500070). The ones on the other side are the front and rear fog light switches.
Why it doesn't work...no telling, but as long as the switch is functional you should be able to wire them up.
If you want to bypass the Rover wiring (other than a relay controlled by the high beam circuit) it should be easy using a latching relay. I think the switch isn't a latching switch so that's why you'll need a latching relay.

 

Yes, the problem is the factory relay doesn't work. Some say it is because it has an off road sensor, others say it will come on for only a minute or two, others (myself included) have no idea! In the 00, it was below the front/rear fogs. In the 04, the fuel door release is there so it is moved to the right side. And yes, it is not latching. I would have to use a cruise switch if I wanted latching. I think I will try to go the bypass route to see if I could just eliminate the LR black box, but might have to just go and do the high beam hotwire like in the last one.

 

As long as you use a latching relay, and the switch is in fact good, I can't think of any reason you can't bypass the Rover wiring entirely.
Being acted on by an off-road sensor (assuming that means it only works off-road) makes no sense. Driving lights aren't what you want off-road.

 

Well, I fixed it! I just wish I knew what I did lol. Fiddled around with some of the wires, took the switch out to look around, etc. Before I dissected it all, i turned the high beams back in, and pressed the button, and bam...we have light. First just one came on, then I turned them in and off a few times, and the other came on. Once pushed, they go on with highs and off with lows. All good!
I will leave them on for a bit later to see if they stay on when driving. I've heard many that go out after a few minutes. On my 00, I would get them to work but just briefly. So, for now I guess problem solved! If they do spaz out though, my money is on that odd black box full of an epoxy type sand.

 

SNAFU,
I wired the Official LR driving lights to that switch in my 2003. I got a genuine kit on eBay for a Range Rover and then took my time. All works well. But i do have to manually turn the lights off when I stop the car. I've never thought the flood light pattern t help out that much at night. I added HID bulbs to mine, so they are a little better. Still a scattered beam or no "beam" at all.

 

I just have to adjust them a bit more. On my 00 they made a great difference. They are Hella on the 00 and LR on the 04. The Hella are bigger and brighter, but were great. I drove with them on the 04 tonight, and seemed a bit more focused as a beam. I'm just looking to aim them up the road and to the sides a bit more. Even though I'm in NJ and not far from NYC, you would never know it. I have hit 5 deer (not with the Disco) and a bear (with the Disco). The further up the road and to the sides I could see the better! I made 50 ski trips where I'm driving back in the dark just about every time.

 

OK, so they have been hit and miss all week, but noticed a few things:
They only turn on initially when the vehicle is in park. I tried turning them on while driving last night and they didn't go on. Got home a minute later, and hit the button again for the heck of it, and went on. Shut off truck, did the same again with same result. Also, the other night they turned off after a couple minutes (when I came to a stop, not sure if that mattered). They didn't go back on. When I got where I was going and got back in, they went back on and stayed on (while high beams were on) for the rest of the 30 minute drive.
I'm thinking that little black relay box (and or the computer) does in fact control these with odd rules.

 

Ahhhh....never mind. Blew that hypothesis out of the water. Lets just leave it at this: Like most things on a Rover, they work when they feel like it.

 

OK...they are back to not working and the amber light on the switch stays on all the time, even when the truck is off! Amazingly crappy and complex set up for driving lights! Time to cut out the relay and just hook they via a simple relay to the high beams like I did on the other.