One Wire identification NEED help!

[S13_coupe]

91 coupe Ka24de 5 speed swap.

there is a thicker gauge solid white wire coming from the bottom of the fuse box specifically under the grey 'Alt 75A' fuse. and when the battery is hooked up that wire is hot. For the life of me don't know where it goes though. if anyone could take a peep under their box and trace that wire and let me know it would be greatly appreciated

[centralcoaster33]

Well, I took a look at mine. Most of my white heavy wires actually have a red stripe on them. I do have one from the 75 Amp fuse for the alternator though. I didn't trace it with a voltmeter, just visually. I appears to go down into the sub-harness for the Transmission/ Starter/ Alternator and then it goes to the large bolted on alternator wire. No surprise I guess, since it's the Alternator fuse. Is your alternator grounded? You should have the heavy wire that bolts on, a smaller yet still heavy wire in black for the ground on the alternator chassis and a plug with smaller wires for the thinking part of it all. I hope that helps. There's always the wiring diagrams in the FSM.

[S13_coupe]

Well, I took a look at mine. Most of my white heavy wires actually have a red stripe on them. I do have one from the 75 Amp fuse for the alternator though. I didn't trace it with a voltmeter, just visually. I appears to go down into the sub-harness for the Transmission/ Starter/ Alternator and then it goes to the large bolted on alternator wire. No surprise I guess, since it's the Alternator fuse. Is your alternator grounded? You should have the heavy wire that bolts on, a smaller yet still heavy wire in black for the ground on the alternator chassis and a plug with smaller wires for the thinking part of it all. I hope that helps. There's always the wiring diagrams in the FSM.

Correct, there is a thicker black wire grounded on the alternator then a white wire that connect to the big bolt and then the 2 prong connector. My issue is that the white wire on the big bolt of the alternator that comes off of the lower harness is not a power wire lol I tested it. But the white wire coming from under the fuse is powered. if I knew how to send a picture I would. There's a wire that runs to the positive terminal of the battery...goes down under that fuse.. comes back out from under the other side of the fuse (white wire) and it's getting power. Not sure if I take off the one that's from the lower harness and attach that one or what.

[S13_coupe]

[centralcoaster33]

I can't tell without pulling all my wires apart like yours. Try the wiring diagram. I think you'd have power come from the alternator, through the wire, through the fuse, through the next wire, to your battery (this is how it gets charged). So check the fuse between the two. Should have continuity. If ones hot and the other is not, then I suspect a bad fuse or wire somewhere in there.