Just did this mod last night - two thoughts:
I removed the terminals from the map light connector, rather than cutting into the wires. If you do this and terminals contact each other, the fuse will blow (from experience
). It's the 20 amp fuse (fuse #8) by itself at the front of the underhood fuse box.
when I looked at the schematics, I didn't see the need for the terminal switch/wire cut, as the switch is shown to be on the ground side of the bulbs - this is not the case, hence the need to either switch terminals or swap wires, as the map light switches supply +12v with a constant ground, and the body control module which controls the dome light supplies a switched ground, with constant power.
As well, I didn't solder anything to the map lights. Instead, I stripped off about 3/4" of insulation on my 12g wires, twisted the strands together and then twisted that into a small loop (about 1/8"). I hooked the loops (one for each map light) onto the end to the maplight bulb, and put the bulb back into the holder arms. The wires are held securely by the bulb end, and I didn't need to worry about melting the switch. My only issue will arise when I have to eventually replace those bulbs, but I left a fair amount of slack for wiggle room, so I don't think I will have too many issues.
Great Mod - Thanks.
PS - I have a wagon with a sunroof, and checked every wire in the map light area. None of them supply the ground for the dome light, so I removed the sunroof trim and snaked the wire through the headliner - It wen't quite easily. The trim was easy to remove and reinstall.