what does this wire do?

[67cst]

this is probably a longshot here but i know there is lots of traffic on the board so i thought id give it a shot, im having problems with my 78 datsun 620, my battery isnt keeping a full charge, at first i thought my alternator was hooped but then today i discovered i have a bad connection (the wire coming off the pos battery post)...does anyone know what it does? it disapears into the wiring harness and its hard to follow, could it be the reason why my alternator isnt keeping the battery charged? sometimes my truck is completely dead when i turn the key, if i pop the hood and jiggle the wire it fires up first try, so what im thinking is maybe this wire is working sometimes, like when i start the truck, then while driving its gets jerked or something and the connection is cut off causing the battery not to be charged..i know its a longshot but if this is the problem it will save 120bucks for a new alt....i have pics to show but right now i cant upload any of them for some reason, ill try later,

thanks guys

[67cst]

i just read my post and i should mention that im talking about the small wire coming off the clamp around the post, not the actually positive cable going to the starter

[Longhorn Man]

That is probably your charge wire.

[68C15]

I believe that wire feeds the constant hot side of the fuse block. I used to have a plethora of late '70s Datsun pickups.

[67cst]

im not sure exactly what it does...but when i pull the connection apart the motor dies...

68c15, sounds like this isnt related to the battery problem?!?

[68w/sbc406]

that wire is the power supply to your car, when you pull it off nothing gets power.

[Brainchild]

It still should run,if the alternator is working.You should be able to pull off both battery cables and it remain running.

Sounds like the alternator is gone to me,have it checked.You might save some money just replacing the brushes,and not having to buy a whole new unit.

[67cst]

i looked into rebuilding this 35 amp bad boy alternator and they said it wasnt worth it and to replace it with a new one,

thanks guys

[68w/sbc406]

i would look at replacing that part of the wire, you shouldnt have to jiggle the wire for it to start, i dont know dautsuns, but is the wire you're talking about the fuseable link???

[68C15]

get a wiring diagram. it feeds the fuse block which also feeds the ign. switch which feeds the alt field & everything else on the truck. the other wire from batt. is just to the starter motor for high current. does this make sense? (620 means regular cab truck right?)[I think 621 means king cab truck]
check for corrosion inside the wire as it sounds like you have one of those "repair" cable ends where the conductor is not sealed from the enviroment. the batt + post is on top right behind the gap between thr hood & rad. support. moisture is kind of forced in there while driving while batt. vapors are rising from the service caps & joining the barrage to further the damage. after repair coat the area with grease.

[67cst]

i got a new alternator today and the truck runs like a hot damn

thx guys