Hello. I just bought a 55 ford f-100. It has a 78 ford engine in it, and I got it running, but I'm not charging. I checked the alternator, and its good. I look at the voltage regulator, and there are 4 slots marked with I A S F . The S&F slots are going to the alternator, the A slot has a yellow wire, but it isnt connected to anything, and the I slot is empty. Could someone help me figure out if this wiring is right, or what the IASF slots mean? I would be eternally greatful!
Thank you.

 

[font size="1" color="#FF0000"]LAST EDITED ON 15-Apr-01 AT 05:25 PM (EST)[/font][p]If your truck has a idiot light:
you should have a green-red stripe wire running from I terminal
on regulator to a 500 ohm resistor to a charge lamp in dash to the
ignition switch.
the A terminal on the regulator (yellow-white dot) should run to
the battery side of the starter soleniod.
the S terminal(white-black stripe) goes to the stator terminal on the alt.
the F terminal(orange-light blue) goes to the field terminal on the alt.
the bat terminal (black-red stripe) on the alt. goes to the large solenoid terminal that goes to the battery.(also where the A terminal went)

If your truck has an ammeter

"S" terminal on regulator (green-red stripe) goes to a hot in run on the
ignition switch.
"F" terminal on regulator goes to field on alt
"A" terminal on regulator goes to large terminal on starter solenoid
that goes to the battery.
"BAT" terminal on alt goes where the "A" terminal went on the
solenoid.

With an ammeter there is no connection to "s" on the alternator except if you have an electric choke, and no connection to "i" on the regulator.

 

[font size="1" color="#FF0000"]LAST EDITED ON 15-Apr-01 AT 05:45 PM (EST)[/font][p]https://www.ford-trucks.com/dcforum/User_files/3ada21e51c40261d.jpg

 

Thank you very much. I will set it up tomorrow, and see if things work out. I will post the outcome for you.

Thanks again!

 

Well, I purchased a new voltage regulator, and installed it, wired it like you said, and I am still not charging. I unhook the negative batt. cable, and my engine turns off. I dunno. Any suggestions?

 

Don't give up !! Franklin2 gave you a great schemetic. Need to check for continuity at both ends of the wires. Disregard wire colors, rather check where they come from and where they go since conversions rarely use the proper colors. An additional wire that shold be there is the ground. It goes from the "gnd" post on the back of the alternator to the engine block and then on to one of the sheet metal screws mounting the regulator.

Need to know -- do you have a dash warning light or a factory ammeter ??

Seems to be an incompatibility on your wiring since originally you mentioned the "I" terminal on the VR was not used yet the "S" terminal had a wire going to the alternator. This cannot be right.

Describe what you did so far and I think we can sort through it.

FL Panhandle

 

Is pulling off the negative battery cable a valid test? It scares me when people do this, because the battery is the only thing that holds the trucks voltage down in the teens. If something were out of whack who knows what the voltage would spike up to and then good by electronic ignition. Check the battery voltage with the truck off. Then check it again with the truck running. It should be higher running-how much higher depends on how drained the battery is.

 

Ok. The wiring on my ALT. has 3 main wires coming off of it. 2 small wires and a thick black wire. the 2 smaller ones are going into my VR, The thick one is going through my firewall and into my cab, connecting into my volt meter in my dash. The other connection from my volt meter goes to the battery side of my solenoid. I am noticing that there is a connection on the back of my ALT. marked "gnd" that is not hooked up. Maybe this is the problem? That might help huh? I'll check it. Thank you.

Does this sound right?

 

[font size="1" color="#FF0000"]LAST EDITED ON 17-Apr-01 AT 06:29 PM (EST)[/font][p]Is this wiring homebrew? You said you have a voltmeter. Verify for us that it is a voltmeter or an amp guage. Regardless of what it is, it's not hooked up the "normal" way. I have a 65 mustang and a 1980 f150 and believe it or not they are hooked up generally the same way. The large wire from "bat" on the alternator is 10 guage and is kept as short as possible going directly to the battery post on the solenoid. This post on the solenoid is usually the main 12v connection to run the whole vehicle. Thinking of how big a mess this could really be if it is homebrew I hesitate to make suggestions because I don't know how familiar you are with vehicle electrics. I made my own homebrew wiring for my 53 f100, but I actually used the schematic I have for my mustang, copying the wiring practices of Ford, thus assuring I would not have a problem.
OK, let's leave the big wire alone.
Leave the little wire going from "field" to "f" on reg.
I assume the other little wire is going from "stator" to "s". Take this wire off of "s" on the regulator and tape it(don't use)
Do you have a wire going from "a" on reg to the bat post?
Take a new wire and temporarily hook it from "s" on reg to a hot in run. A easy place to hook this is the + on the ignition coil BEFORE the resistor.
If you do all this, that darn thing should work.

 

Your wiring is definitely wrong,in fact, bizarre. The wiring through the voltmeter seems more like for an ammeter and is at least suspect.

Job 1 should be to just get the sparkenmacher working. Recommend the following:
1. On the back of the alternator -
a. remove the wire off the "sta" terminal and tape it
off. There should be no wire at all on this terminal for
your application.

b. Install a ground wire to the "GND" terminal as described
earlier.

c. Remove the heavy cable off the "BAT" terminal and tape
it off. Run a similar wire (10 Ga) from the "BAT" terminal
directly to the + battery side of the starter solenoid.

d. Check to ensure that the "FLD" wire from the alternator
goes to the "F" terminal on the regulator.

2. On the regulator -

a. Ensure that no wire is attached to the "I" terminal.

b. Run a wire from the + battery side of the starter
solenoid to the "A" terminal.

c. Run a wire from a key-on power source (like the + coil
wire ahead of the resistor) to the "S" terminal.


This procedure takes the questionable dash voltmeter out of the system for the moment. Start it up and measure the voltage at the battery terminals. If it reads 13.5 to 14.5 volts or so it is working. We could then delve into the voltmeter dilemma. If no luck, recheck wiring and also check continuity of wires to ensure no wires are broken. If still no luck either the alternator or regulator is bad. The alternator can be checked while in the truck. Tell you how to do that later if need be. The regulator would have to be bench checked.

Think you are getting good info. Hope this helps.

 

Thank you soooooo much. It is 10:30 pm right now, but as soon as I get some light, I will check it out. I wish my damn printer worked.... I will keep you posted, Thanks again!

 

[font size="1" color="#FF0000"]LAST EDITED ON 18-Apr-01 AT 01:15 AM (EST)[/font][p]one more thing. The person that owned, and switched the engine in my truck was obviously a tweeker (user of crystal meth). I think the guy just tore out the original engine (6 volt system) and re-wired it like it was. The wiring is all screwed up, and this is my first project. I could take it and have it done, but I really want to learn my truck. I understand what you are telling me, and feel like going out to the driveway and making some noise, but I will have a little self control and wait till morning. You should get a load of the mangled bowl of spaghetti under the dash. Thats a different story. Oh! how could I forget 2 kill switches, a push button ignition, and a key switch. Paranoia? Man, this guy needs help.

 

Well, I hooked it up like you said, and IT WORKS!!! running and charging like a champ. Now I have a small dilema. The only way I have a continuous spark to the coil, is to run a wire from the + side of the solenoid to the + side of the coil. Any suggestions?

Thank you sooooo much.

 

Voltage to the coil should be stepped down by a ballast resistor. The best way to do this is to identify the threaded stud on the back of your ignition switch that is for ignition (provides voltage when the key is on). If your switch is like most old Ford switches there should be four studs (12 volts in, accesories, starter, and ignition). Once the ignition stud is identified, run a wire from it through the firewall to a 1957 - 59 Ford ballast resistor (available from parts store), to the + coil stud. Just after the ballast resistor a wire should be run to the "I" stud on the starter solenoid. This wire provides a full 12 volts to the coil for a hotter spark when starting. HTH

 

I think we are getting back to the big wire issue (the one you said went from the alternator directly through the firewall). You said the truck will not stay running-what else doesn't work? I would venture to say alot of stuff doesn't work now, because we changed the distribution of the main 12v that runs the truck. You need to find out what is your main hot wire that feeds all the underdash stuff. I would go ahead and make the large solenoid stud that goes to the battery, the main connection point, and feed this through the firewall. This wire should be at least 10 guage and it is NOT FUSED so be very careful how you run it. On my truck I ran it in and connected it to a stud I mounted in plastic and mounted to the inside of the firewall. From this point you spread out and run everything that needs power. I ran a wire from this point to my original ignition switch for key on power. Then run a wire out to the coil. This is the ONLY circuit I ran that is unfused. Everything else that is run from the key on circuit or the central connection point at the main feed wire must be fused (or circuit breaker) or you run the possibility of burning your truck down! If you have the money, one of those aftermarket street rod wiring harnesses would be the way to go.