In Panasonic digital, the absence of a phone will light the BLF. By default, the numbering starts at 101, so the extension for 102 is the second port in the system. That's the 2nd port, left to right, on the bottom row 4-port card (DHLC, black jacks).
So, as suggested, take the phone and a 4-pin line cord, and plug it directly into that port. If the phone lights, you have a wiring problem. You already said the phone works, so I'm guessing that's your problem.
Carl
