No power to anything in the chassis, like the room lamp, etc... would most likely the result of a blown fuse in the engine bay. It wouldnt be effected by the engine wiring. Go to the passenger side fuse box, take the cover off and inspect all the fuses closely. Especially the alternator fuse, its the big grey one that says 75 amp on it. Check for bad grounds.... yadda, yadda, yadda.
How many times has this been addressed before?This link my prove to be very useful...
zerosearch HIJACKER where is that gaint search button at??? It could come in really handy sometimes lol!!!