On a '00 S40 this is how it goes, should be the same to at least '03... If you're talking about the corner light I think you're talking about then you'll have no prob getting it out. Just look down on the corner lamp assembly from above with the hood open and you will find a screw that is easily accessible (facing up), just loosen it up a bit and pull out the whole corner lamp. There is a little plastic tab sticking out on the inside of the corner lamp you may have to depress in order to get it to slide out, but be careful - it breaks pretty easily, so I guess you don't have to press as hard as I did. Then just unplug where the harness plugs into the lamp. You can get the assy. for relatively cheaper than at the dealer if you look around a bit online. BTW this is also how you change the bulb.

Greg