blowing 3 fuses

[slimcat7m3]

I have been battling a short in my car for some time and can not seem to find it. The car is an 89 240sx w/ sr20det 5 speed, apexi avc-r. I did all the work on the car, and at the moment the car is about gutted because I have been looking for the short. I am blowing the taillight fuse anytime I turn the headlight switch on, therefor, no taillights, side marker lights, or instrument cluster lights, however the headlights/blinkers still work. I purchased a TCU at the junk yard and still had the same problem. I checked both TCU's for burn marks or anything irregular and don't see anything on either one. I have also been having problems with my alternator charging. My old battery wouldn't hold a charge (was told it had a bad cell) so I purchased a new one. My alternator is charging, but it seems the alternator is running my car. The battery light was on and my alternator had quit charging so I had it rebuilt. When I installed it the light was still on, and the alternator would only charge after I had revved it up, within two weeks it quit charging so the rebuilder fixed it for me. Same thing, alternator light still on and in about two weeks it died. I purchased another alternator and installed it, same thing only this time I haven't driven my car so I won't ruin the alternator. According to the FSM I am blowing fuses B, K, and M. When I follow the wires on the schematic the all meet at the ignition relay, but was told that a bad relay wouldn't cause a fuse to blow. Getting really frustrated and almost ready to take my car to a shop. Any help would be appreciated.

[180fan]

have you taken a gander inside those sockets for the bulbs? if you see carbon build up in there it could cause the short.