Dang it...this is driving me crazy. I've looked at the FSM and I'm just not getting it. On an S5 alt, what is the second wire that attaches to the post connector (circled in red in pic)? One comes from the output side of the 100A main fuse, but what is the other one?

 

I figured someone with a series five car would have had an input by this time. I don't have a series five so I can't say for sure. The wiring diagrams, for sure don't show two wires.

Since you were able to follow one wire back to the MAIN FUSE, I'd have thought you could also follow the other wire back to where it attaches. Then again, the original cable was supposed to got to the Main Fuse, so maybe you followed the original cable successfully.

My GUESS, is some one added another cable b/t the alt and the battery positive cable?????? Because he couldn't figure out this that or the other and just added cables to the car?

IN the diagrams it goes from the Alt to the Main Fuse. It also, thru a splice I suppose, goes to the ignition switch, on a much smaller wire/cable. So you now have been officially been BUMPED TO THE TOP OF THE LIST OF THREADS! Whee.

 

series 5 have a dual wire system from the B+ from factory

one runs to 100 amp fuse

the other runs to ignition switch

its an upgrade from the series 4 alt which is rated at 70 amps and runs a single wire

its one of the ways to tell if your car is running which harness

 

Thanks for the info guys...after studying the wiring diagram again I was assuming that the second wire went to the ignition switch. Now I've got confirmation!