You don't need to turn on the key, the INT LAMPS fuse is always hot.
First, if you have access to a voltmeter, get a large hammer, 3-5lbs, and smash the SH1T out of your noid light. Always use your meter and if you don't have one you can get a cheap one for around $25.
1: Pull the switch assembly on the drivers door.
2: Put your meter on ohms (resistance) and check from the black wire to one of the hinges. You will need to find a good clean spot on the chassis to get contact. You should read very close to zero (less than 1 ohm).
3: Now that you have established you have ground. Put the meter on DC volts and measure from the LG/Y wire to the back wire. You should see >12 volts. If you find 12 volts here then your switch is probably bad.
4: At this time you have no power to the switch. You will need to expose the splice. If you want to test the mirrors at this point, jumper a wire from a fused 12 volt source to the LG/Y wire (I used the power at the lock switch until I had time to fix the splice)
5: Time to fix the splice. Move the drivers seat as far back as possible. Remove the plastic cover from the drivers sill, the seat belt is a minor pain but doable. pull back the rug and rug-mat towards the tranny as far as possible, if you wedge it under the brake pedal it might actually stay out of your way.
6: Now you will be able to see into the door sill where the wire harness is. There will be a plastic peice bridging the the depression where the wiring harness is, remove this becase the splice is in the harness under it.
7: carefully unwrap the electrical tape from the harness like explained in the last post and search the bundle for the LG/Y wire. The S229 splice is actuall two splices about three inches apart (on my car). You will need a 1' peice of good quality 16 or 18 guage wire to repair the splice.
Do you know how to solder? If not, are you willing to take 20 minutes to practice on some scrap wire? I can post you through the basics and the tools will cost less than $20 at radio shack.
Aaron