Correct connection of Alternator Field Terminal wires

[MSN Member]

From: wendell  (Original Message)
Sent: 9/5/2006 12:55 PM

I have replaced the alternator in my Winnie--74 model 440-3 engine and everything seems to be AOK.  This was a part of a pretty major deal where I had the radiator re-cored, replaced the water pump and fuel pump and alternator all at the same time which I had the front end taken apart.  Took about a month, but I'm finally at the end of the job and anxious to get on the road again, but I've run into a snag. 

There are two wires going to the "field" terminals on the alternator--one is more or less in a vertical position and the other in a horizontal position.  When I pulled the old alternator, the wires came off before I could get them labeled properly (my bad), so I'm not 100% sure I have the right wire on the right terminal. 

My wiring diagram isn't very helpful, all it shows a wire going from the electronic voltage regulator going to one of them, and the other wire goes in the wiring harness back to a junction where several wires come together.  But it doesn't show which goes to which terminal on the alternator.

When one of you guys is under the hood, can you take a look at yours and let me know which is which?  Or maybe it really doesn't matter?

Thanks,

WG



From: denisondc
Sent: 9/5/2006 5:07 PM

I have to believe the two wires to the field coil would have had different connectors on them IF the polarity mattered at all. I believe the field coil is electrically isolated from the rotor, and merely magnetizes the spinning rotor.
I also notice in the electrical diagrams in the service manual that there is no coding as to which wire feeds with of the field coil terminals. 



From: Slantsixness
Sent: 9/5/2006 3:56 PM

Actually, the two field wires ARE different.

Here's the trick.

Does it work? Yes... you have them right.

Does it not work? then you have them reversed.

One is CLOSER to the output (large) terminal, one is further and 90 degrees to the output.

What happens? if its hooked up correctly, then you are hooking the regulated voltage to the ground via the rotor, and there is no regulated reference to draw the other coil to ground and produce output. It's kind of like hooking a diode up backwards, but it's incapable of damaging the alternator or diodes, because the rotor cannot pass current in this configuration, unless you installed the diodes backwards too!

Ive seen the wires as follows: (and sometimes the factory changed these colors every year...)

RED, Blue or Grey - primary "T1" (regulated input to first (closest) terminal)
DK BLue, Black, Green Secondary "T2" (used to draw the rotor to ground to have current output.

so.. it does matter, but it won't hurt anything if it is backwards, it just won't work!

Oh yeah... for those of us who dont have Dodge alternators, this is only true for Dodge alternators, and only for the alternators with ELECTRONIC voltage regulators (with thte triangular 2 pin connector on the 3X4X1/2" box... like this:

Tom



From: wendell
Sent: 9/6/2006 3:16 PM

Thanks for all your help.  I can sleep better now.  It's charging, so I must have it hooked up correctly.  I had a 50/50 chance of being right.. 



From: c-t1
Sent: 10/15/2006 12:16 PM

I have a 1969 winn. where would my voltage regulator be located ?