I did indeed say there was a BLACK wire coming from the old alternator plug. Oops. And thank you for including the link addressing the BLUE and BLACK wires. I clicked on the link for my new alternator and saw that it was giving instructions for a YELLOW and GREEN combination. I missed the one w/ info on the BLUE and BLACK combo. As a result of your post I was able to install my new alternator this evening and Rosebud is up and running. Thanks!

Must be a slip of the finger between brain and keyboard, but you most definitely say there is a black wire coming out of your old alternator plug in pic 1 - I'm sure you meant brown.

The RAC902 plug comes in two flavours, yellow & green and blue & black - the Powerlite page has some very clear wiring instructions for both types.  //www.powerlite-units.com/products/rac902/ and  //media.powerlite-units.com/uploads/files/2015/04/24/RAC902_Ch5bwIX.pdf

The black wire is from the new alternator plug; (1) blue wire & (1) black wire from the plug.


After reading your post and looking at Haynes I understand that both brown wires from the loom/plug should be attached to the threaded stud on the new alternator. I also know for a fact that the brown/yellow loom wire goes to the dash light. That leaves the (2) wires; blue and black from the new alternator. As you have said, one is the dash light, the other is the sense wire. The question is: which one is which? 

The new alternator is a Powerlite RAC068. It's British made and identified as a "Lucas type lightweight high output alternator" [link]. Their online wiring digram is no help as they show the wires from their plug as yellow & green. Mine are blue & black. I assume I don't need to worry about the sense wire as I didn't have one on the old alternator. 

So, blue to brown/yellow... or black to brown/yellow. Is this something I can verify w/ my multimeter?

I don't see a black wire in your pictures.  Black wires should be for ground connections so perhaps someone ran a back wire from the old alternator case to the engine block.  Shouldn't really be needed.

The brown wires in the old plug will both connect to the threaded stud on your alternator.  To figure out the other two you are going to have to look up what your alternator is (Denso or?)  

In general, one of the two wires on the new alternator gets connected to the old brown/yellow wire.  That connection gives you the dash warning light.  The remaining wire is generally called a sense wire.  It is either connected to the threaded stud on the alternator OR to a switched terminal on the ignition switch.  You need to look up your alternator to see which connection is right for what you have.

Received my new alternator today w/ no wiring instructions. Anyone familiar with this setup? My original alternator has a (3) wire plug coming from my wiring loom; (1) large gauge brown wire, (1) small gauge brown wire w/ yellow stripe, (1) small gauge black wire (see pic 1). 

My new alternator has a (2) wire plug with a black wire and a blue wire and (1) large copper screw terminal coming from the side of the alternator (see pic 2). What goes where? I'm not very handy with a multimeter, but I have one if needed. Thanks!