alternator wiring question '91 743DS

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brambleberry

Active member
Joined
Sep 2, 2020
Messages
25
I have my project 743DS finally up and running again, the last loose string I need to tie up is getting the alternator wired so it's charging the battery.

The old engine I pulled had a totally different alternator, with only two wires going to it. The remanufactured v1702 engine I put in has what looks to be the correct alternator, but it's got tons of posts with cryptic letters stamps next to them. I even called J&N who sells/makes them and they were stumped. The parts number on it is:

JN 400-46001

I'm including a picture of the back, as well as a sketch I made to make the letters more clear.

I currently have just the big red wire attached to what seems obvious, the largest post which is stamped "B". The loose unattached wire is green with a white stripe, which according to the wiring diagram is the only one besides red hot wires going to the alternator. The wiring diagram shows two additional red wires hooking to different posts on the alternator, all 3 of the red wires lead back to the main battery disconnect, one of which connects to the hot terminal on the starter. I don't see these two additional wires anywhere on my wiring harness, guessing the previous owner snipped them.

Hoping someone here has a 743 with a similar alternator and could share a picture of which post the green/white wire goes to. Otherwise, is there danger of frying something by just doing trial and error with the green/white wire? I know enough to take a voltage reading on the battery before starting the machine, then looking for higher voltage when running if the alternator is hooked up correctly (and functional).

I could also steal the old alternator and put things back as they were, but I don't know if that one is working or not, and if this is the "correct" one for the machine, I'd rather go with it.

TIA for any help or advice!
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