Stator wire from Alternator connection

[akirshbom]

Working a 73 which I got running after it sat for many years. Recently pulled it to swap out the front axle and add powersteering. I pulled the column and reinstalled went to start and got nothing
Under the hood found the black and red wire ground to the Voltage regulator had Melted, not sure when but the copper looks very oxidized. Digging further found the stator wire from the alternator laying on the intake along the passenger side not connected to anything. I can’t find another loose wire it may have connected to.
This truck has the original alternator and wiring harness with Batt wire, field wire(orange) and Stator wire(yellow/blk)

Voltage regulator is yellow , green/red and orange, black/red ground

What should the stator wire connect to from the alternator?

Under the dash ignition switch found the yellow wire in poor condition which I repaired. An empty terminal above it and a loose purple wire with no terminal.
The other wires to the ignition switch seem fine is that spade supposed to empty or does the purple wire go there?

Thanks in advance

 

[Slowleak]

The stator wire should connect to a terminal on your electrically assisted choke, if you still have one.

 

[akirshbom]

That would make sense given its location. Carb was converted to manual choke so no wire connection there anymore. Wonder if I could tap into the stator wire at the voltage regulator?

 

[Oldtimer]

Under the hood found the black and red wire ground to the Voltage regulator had Melted,

An empty terminal above it and a loose purple wire with no terminal.
The other wires to the ignition switch seem fine is that spade supposed to empty or does the purple wire go there?

If battery ground cable is not making good contact at block, the starter current ground path may have passed thru blk/red wire and overloaded it.

Purple wire goes to brake warning light switch. It connects to terminal on ignition switch. Terminal on switch is grounded when key is in START position, to verify warning lamp works.


Drawing from seabiscuit68.tripod.com

 

[akirshbom]

Added a new ground wire to the block , now need to find a keyed hot for the stator to Alt. Thinking os using the center post/ACC on the ignition switch and running a wire from there.

 

[Oldtimer]

Stator does not need 12v feed.

Alternator has 3 wires:
Orange, 12v to field, from regulator,
Black/red, ground from alternator to regulator mounting screw,
Black/yellow, 12v output to ammeter in dash, then back to starter relay on a DIFFERENT Black/red wire (thanks Ford).


Drawing from seabiscuit68.tripod.com

 

[DirtDonk]

What Oldtimer sad. Stator wire is output from the alternator. And only when alternator is spinning.
It’s used for the choke only on Broncos.

Cap it off safely for now and keep it for the future perhaps. But you have no need for it at the moment.

 

[DirtDonk]

You might also consider upgrading all of your battery and starter cables. If you don’t know how old or what condition they are in, it’s just cheap insurance to change them.
And while you’re at it, upgrade to a larger gauge.
I consider 4ga to be the minimum and 2ga even better.
Yes, it’s overkill a bit, but usually worth the extra few bucks.

 

[akirshbom]

Thanks Gents! Learned something new! I Always thought the stator “tickled the alternator to start charging. And that the choke and the stator shared a 12 v source. Never consider that the stator was the 12v source for the choke!

 

[jamesroney]

Thanks Gents! Learned something new! I Always thought the stator “tickled the alternator to start charging. And that the choke and the stator shared a 12 v source. Never consider that the stator was the 12v source for the choke!

Watch out. The Stator is not a 12 V DC source. It puts out AC. Which is fine for a resistive load like a choke, or a light bulb. But not much else.

 

[DirtDonk]

And just to confuzzle things even more, Ford had two completely different wiring schemes for the alternator on cars and trucks during this period.
If you had an ammeter instead of a charge lamp, your stator wire was completely unused until your particular vehicle got an electric choke. For Broncos and some pickups, this was in '73. So prior to that, there was no stator wire for vehicles with an ammeter.
For use with a charge lamp in the dash, the wiring went "back to normal" for Ford. Where the stator wire went directly to the "S" post of the regulator.
Well, not always directly, as some late sixties and even maybe early seventies trucks had a third component that worked in conjunction with the alternator and regulator. A "regulator exciter" maybe? I can't remember, but it's listed in the diagrams.
Other than some '66 model Broncos perhaps, for Broncos up to the point they got rid of the amp gauge, the wiring between the regulator and alternator remained the same with only 3 wires utilized on the regulator. Then in '73 the stator wire came into play, but as mentioned, only for the choke circuit.

But these things are why you have to double-check and look over the shoulders of even seasoned mechanics that might be working on your Bronco. They very often still try to wire it up the only way they know, which is usually wrong if they never happened to work on a Ford with an ammeter instead of a warning lamp.
Not that it can't work when wired that way. Just that it doesn't always unless they know how it all works.

Paul

 

[akirshbom]

Thanks again! Great tech!

 

[Quick & Dirty]

Never consider that the stator was the 12v source for the choke!

FYI, the stator output is unrectified, so it is about 7v AC.

 

[Broncobowsher]

FYI, the stator output is unrectified, so it is about 7v AC.

My understanding is that it is half rectified and 2/3s system voltage. Not a pure DC, but not true AC either. A very dirty, choppy, DCish power. Never goes negative, so not real AC.
But all it was there for was to heat the choke coil. And if the engine stalls, alternator output stops and the choke quits heating up. If it were just switched power the choke could open up if the key was on and there was no engine heat. Using the stater wire the choke only opens as the engine is actually running.