Hey fellas,
I am rewiring my 73 f250 with a brand new wire harness from kwik wire. I am stumped with where to connect the alternator exciter wire.
Also, where would I connect the safety switch wire? The instruction book says to connect it to the battery lug?

 

I am going to assume this harness is not vehicle specific? I too need a re-wire and I've been shopping around. I'm a trained industrial electrician, and I'm not looking forward to it. I know that there are some vehicle specific harnesses that are labeled on each wire where they terminate. This one sounds more general. Please let me know how it turns out for you. As for your question, I apologize, but without being there I would have serious reservations about answering it, but I am sure someone on here will be able to.

Brandon
Clemson, SC

 

I'll give it a shot.

Do you still have the original harness as a reference?
And does your instrument cluster have an ammeter, or just a battery charge indicator light? This will make a difference with the exciter wire.
Does Kwikwire say anything about them wanting you to use a "1-wire alternator for ease of installation" or words to that effect?
Just checking...

Are you running a stock old style alternator with external regulator on the fender apron?
I'll assume for the moment that your truck has an ammeter, since most did. But definitely fill in that blank spot so we can be sure.
Are the wires labeled? Is your exciter wire Green by any chance? No matter the color, what you want is the wire that is on in ON and START only. No power in the ACC position.
This wire goes to the "S" terminal of the regulator.

They are marked FSAI on most regulators, but some do not have the letters present. Actually it's IASF, but I can remember them easier the other way and many are mounted sideways or practically upside down anyway, so that's how I read them most of the time!
So here's the order of the three (or four) wires at the regulator if you have an ammeter:

1. F - Field wire, runs from the "F" terminal location on the regulator down to the "FLD" post on the alternator. Original color was Orange.
2. S - Stator wire, or for our purposes, "Switched" wire. Runs from the S terminal to the ignition switch. Original color was Green w/red, but your color is likely a GM color code.
3. A - Armature wire, or for out purposes "Always Hot" wire. Runs from the A terminal to the battery positive so it's sensing battery voltage at all times. Can be spliced into the charge wire from the alternator, or simply connected to the starter relay on the battery side.
4. I - Indicator, or Ignition, is left blank and not used in this situation.

Again, let us know if you have an indicator lamp or an ammeter. If the lamp we can run down the proper wiring in that situation.

Is your truck an automatic trans or manual?

Paul

 

Automatic transmission with a manual 4x4

 

The instrument panel does have a ammeter

 

wire color from kwik wire harness is white.

 

Ok, with an automatic you have a neutral safety switch that interrupts the START wire (Purple/Violet presumably?) from the key to the starter relay.
So Violet runs from the ignition switch to the NSS either at the base of the steering column (inside the cab) or the side of the transmission, depending on which model you have.
From there it runs to the "S" post on the starter relay (not to be confused with the S post on the voltage regulator).
If the NSS works, your starter should only crank in Park and Neutral, as you have already experienced I'm sure.

Since you have an ammeter, your wiring at the regulator is as described previously.
When I said "three (or four)" wires at the regulator, yours has three positions filled (with the "I" position left blank) but you will likely have 2 wires at the A terminal. One is for battery sensing power, the other is for the radio noise suppressor capacitor that is likely bolted to the side of the regulator.

Also, since you are probably not using the original harness from the back of the alternator, you will also want to add a ground wire from one of the GRD studs on the back of the alt, over to one of the mounting screws at the voltage regulator.
Does not have to be a big wire either. Factory used something tiny like 20 or 22 gauge. But whatever you have handy for making ground wires will work. I usually end up with a 14g wire because that's what I have the most of laying around.

White, eh? Interesting.
What wording is printed on the side? It says regulator exciter specifically?

Paul

 

Ok. First things first. Picture one is how I inherited truck from my FIL..






Picture 3 and 4 is the plug that goes into the external regulator. To which terminal do I hook the white wire too? 1,2, or 3.

Picture 5 is the Alternator exciter wire looking for a home..

Picture 6. Is the purple neutral switch wire also looking for a home. That one is coming directly from the fuse box.

Picture 6 also shows the red wire that's says needs to be connected to the starter

battery lug? what side of the starter solenoid do I hook the purple and red wire too..

 

The White wire goes to #2 where the original Green w/red wire is now.

The Red wire is probably the battery feed to the fuse panel, but what exactly does it say on the side? You said "starter" but does it say "starter solenoid" or "starter relay" instead?
If so it attaches to the battery cable side of the starter relay (solenoid thingy).

The Violet/Purple wire you need to test. It should not be coming from the fuse box but from the ignition switch. Maybe they have it routed past the fuse box, or through one of the fuses, but here where you need to test.
Does the Purple wire have power when the key is in the OFF position? What about the ON position? It really should only have power in the START position.
Once everything is determined for sure, the Purple wire is probably going to end up on the small "S" terminal of the starter relay. That's the small one on the left, with the original Red w/blue wire.

Is there an online page for their instructions that I can read? If so, got a link?

Paul

 

Another things to work on before you get it fired up. Grounds....
With an older vehicle in that condition, where the wires have been compromised for likely a long time, and with obvious surface rust on the visible panels in the pictures, some things that need a good ground may no longer be getting one. Which can sometimes, while tracking down other issues, can lead to the original wire modifications to begin with!

Things like the voltage regulator. So "since you're there" anyway, remove it from the body and clean up the surface underneath with some sandpaper or even a Scotch-Brite pad. Anything...
And where the big negative battery cable ends up on the engine block, clean that surface and the threads for the bolt the best you can before you connect it. Same for the small ground from the battery to the body nearby.
In fact, a good place for that secondary ground is one of the bolts holding either the regulator OR the starter relay. Both need good grounds, and both can benefit from the long-term benefits.

Paul

 

everything is disconnected so far.

 

Do I splice the white wire with the original green w/red wire?

 

Up to you, and a few different ways you can do it.
You can splice it to the existing Green w/red wire as long as it's in good shape (easiest option most likely)
You can figure out how to terminate it with the proper connector to fit into the original one. (most trouble I think)
You can buy a brand new 4-position regulator connector at any parts store and splice the new wires to the new ones. (relatively easy and the best option if the old wires are in bad shape)

Paul

 

Looks like they leave the Purple wire in one piece originally (as I suspected, but why I wanted you to check) so you can use it as-is with a manual trans.
In your case you need to find the NSS on your truck, run the Purple wire from the ignition switch and cut it there. Attach the ignition switch wire to one side of the neutral safety switch. Then with the remaining Purple wire, connect to the other side of the NSS and on out to the starter relay over by the battery. Connect to the small "S" terminal as previously described.

Paul