Hi, everyone!

I just bought myself a 73 F-100, manual, 302 to use as a work truck. However, it needs a little work first before it can actually do some work

The problem is that the previous owner had a fire underhood, that destroyed a lot of wires. As a result, he rigged up some awful looking mess of wires, just to get the truck running, that any family of birds would be proud to nest in

Well, the good news is that the truck will run. The bad news is the battery dies everynight if left connected, because the coil and other various components always have power, and that the charging system doesn't work. I have never seen such a pathetic wiring job in my life. To give you an idea of how bad it is, the ground strap that bolts to the engine block was connected to the + side of the battery. I am amazed that the truck would crank, and that nothing in the ignition burned up.

So, here is what I am faced with. Rather than try to sort this mess of wires out, it will be easier to me to just run my own wiring harness. The only area of difficulty is the charging system.

On this alternator, there are 3 wires: Battery, F, S. The Battery connection is easy enough. I assume that ground comes from the physical mounting of the alternator. What do I do with the Stator and Field connections? Keyed 12V from ignition switch?

Also, does a 73 have an external voltage regulator, or is it built into the ignition module or alternator?

I need to buy a book for this truck, but I have my doubts that it will answer all of my questions.

The absolute best thing that I could use is a wiring schematic.

Thanks in advance for any comments or suggestions!

 

Welcome to FTE!

The title of this thread has received a title change by administration to " Best reflect the TOPIC".

 

Here's the wiring for the alternator. This is for a truck that does not have an idiot light. If you want the idiot light, it will need to be wired a little different. If you have the money, a wiring harness that is made for street rods would be the way to go, since it is universal. You could make it fit, and it's all color coded and super nice. But they are expensive. I made my own harness for my 53 ford, using a 65 mustang wiring diagram as a reference. The mustang had the bare essentials, no bells and whistles to complicate things.

 

I would go to a scrap yard and pull the wiring harness out of a truck. You may have to get two and make one out of them. With the harness you get all of the proper connectors. When you get the harness you can peel the covering off and split the harnesses out and inspect the wires etc. I assemble my harness with spiral split tubing cable wrap available from Radio Shack.

 

Thanks for the diagram! This will help a lot!


Regarding the diagram, I take it that the 73 has an external Voltage Regulator? If so, where is it located? I couldn't find one on the truck, but then again I wouldn't doubt if the previous owner left it off

Last question, the stator connection on the alternator connects to the electric choke on the carburetor? This seems a little odd, but if that's the way it goes, then I'll wire it in that manner.

Thanks again, everyone!

 

The voltage regulator should be on the right fender apron.
A shiny silver box mounted next to thr starter relay,unless the fire got to it too.

 

You're right, it's there!

The only thing that is still unclear is the stator connection in the diagram. It has a wire going to choke. Is this actually going to the choke on the carburetor, or going to an idiot light, or something else. Is it essential to have this wire connected to get the charging system working?

 

Electric choke on the carb for sure.
There should still be a wire to the stator connection other than the electric choke.

 

"Is it essential to have this wire connected to get the charging system working?"

No, you don't have to hook anything to the stator terminal for the charging system to work, if you wire it like the above diagram. If you don't have an electric choke, just leave it off.

 

Ok, that answers all my questions. I'm ready to tackle this project now. Thanks again!

 

Just a follow up.

Worked on the truck last night, and the charging system works!


But, I had several problems to overcome. The field wire from the alternator to the regulator was broken, the bat wire from the alternator to the battery was broken, the 12V line from the battery to the regulator was missing, and the connector to the voltage regulator was severely corroded.

So, I ran new wires and even put them in looms. For good measure, I replaced the regulator and solenoid(Less than $20 for both - gotta love old fords!). I cleaned the voltage regulator plug the best I could, but it's still not great. Does anyone sell a new voltage regulator plug?

To verify that the charging system was finally working, first I measured the battery voltage with the engine off - 12.9V
Then I cranked the engine, and the same measurement was now 14.7V. Then, with the engine still running, I removed the negative terminal on the battery, and the engine kept running. For the last test, I shut the engine off, and connected an amp meter in series with the battery. No amps being drawn with the engine off

So, for those of you following this saga that may have a similar problem, just take your time and the fix is really easy.

 

You're lucky you didn't blow the diodes in the alternator when you removed the battery cable with the engine running.

Never do this.
This practice that some people do is from back in the days of GENERATORS not alternators.