audio help plz!!!

[slickSX]

I am new to the forum and tried the search but came up empty. well anyway heres my problem:

I took out the old aftermarket stereo that was in the car. who ever installed that one did a jimmy rig a$$ job on it. but that's not the problem. when i yanked the stereo out. i noticed 4 plugs to the car harness (1 large white plug, 1 medium white plug, 1 small white plug, and 1 small black plug). when i pulled the old stereo out all the inside lights turned off and my clock doesn't work anymore. and i notice that the automatic seat belts don't move unless the car is on.

i have set up two plugs which go into the stereo harness and now left with the small white and small black plugs. I think that the reason all the electricals inside don't work is because one or both of those small plugs needs to be plugged in. But i don't know where they go. if someone has a 92 240sx fastback and can help rememdy the problem please help. I have done stereos before, but when i pulled out the old stereo i wasn't paying attention to where the black plug came from it sort of just slipped out. and i didn't notice anything plugged into the small white plug. i know its my bad, i shouldve paid more attention to what i was doing.

[xekushnr]

there is a white box in the drivers side footwell near the fuseblock. it is called the TCU. replace it.