JCB 1400B Lucas Alternator wiring

[jrserra]

I have a JCB 1400B with messed up wiring. I'm trying to get the alternator working. I need to know what the wiring scheme is. The alternator has 3 spade connectors. The top one has a lighter gauge wire, and I suspect it is the exciter wire. The bottom 2 have heaver gauge wire. When the engine is running and the key is on I measure about 4.7V on the top wire and 12.7V on the bottom 2 wires. 12.7 V is the battery voltage. That reading does not change when the engine is reved up and the voltage drops when I put it in forward/reverse. Can I put 12V in the top terminal to energize the alternator? How do I test it?
John

[gecko.cx]

Have a scan down this page and see if your alternator is present.
The is a circuit diagram at the bottom that looks about right.
Is your charge warning light working correctly?

https://www.caretxdigital.com/

(got the manual?)
There is a charge testing procedure in the manual (Page 3-2)
The manual shows three alternator models, so ID'ing is the first thing on the program.

[Jeremy Rowland]

Hi John and welcome

Jeremy