It depends on your car's model year and what country it was built for.

For at least some model years in the US, there is a small slot
screwhead near the light switch; when rotated to a certain position it
disables the daytime running lights. For places where DRLs are
mandated by law, no such screw exists (but Canadian and US cars get
the same manual, which is how I know of it).

Others can tell you whether there is a simple answer if your car
doesn't have this screw.

Chip C
Toronto

[peter] (22 Jul 2004 06:27:32 -0700):

On the 850 I removed the pins 5 and 8 on the switch, worked flawlessly :)

Thanks to Chip C but I looked around the switch area and can,t see
anything extra.mind you it says in the Uk Users Manual 'Go to a
dealer' for this.
Perhaps it has to be programmed these days. I was hoping for something
less painful!
Also Sveins switch mod sounds more hopeful, but more time needed here
to do it !! Any other ideas anyone ??