Hey guys, I'm trying to sort out why my alternator isn't charging.

Background: 66 F100, 390, new alternator, new voltage regulator, new battery. I redid most of the wiring harnesses, changed over to plug fuses. Went to factory wiring for the most part.
I had the new alternator tested and it tested good however I was told they do not connect the Field post during the test and I'm wondering if that's what is causing all the trouble. (Field post not working).

Issue: Alternator went out, changed both the alternator and voltage regulator (BW). I understand how to read schematics and currently have wires (all new) connected as factory schematic.

From Reg. To Alt.
"I" post unused.
"S"-"Sta".
"A"-hot side of starter relay then to "Bat".
Aftermarket voltmeter connected to "Bat" post on Alt.
"F"-"Fld"
Alt. is grounded properly as is the voltage reg.

Question 1: Buddy of mine recommended running Stator wire from the voltage reg. to positive of coil. This worked but I need someone to explain how, and if this is going to damage anything? (This means there is no wire connected to the Stator post on the Alt.)

Question 2: My original Alt. had all of the post on the passenger side. This new one has them on the driver side. Does that make a difference? They both spin clockwise and fan blades on new are set to pull heat out which is correct.

Moral of the story, I don't want to have to run a wire from the "s" terminal of the voltage regulator to my coil. And if it has to, I would like to know why when my last Alt. was not wired up this way and worked fine for the better part of a year since I have owned it.

Thanks.

 

I'll take a shot at some of your questions and ask a couple. Are you using a OEM style mechanical volt reg or a newer electronic volt reg?

1- For an alternator to put out, the field HAS TO BE energized. The volt regulator CONTROLS what the alternator does. You said " Went to factory wiring for the most part". Lets assume you did the charging circuit as Ford intended it. When you turn the ignition switch to ON, you power the I term of reg. It tells the reg to energize the field of the alt. Refer to this link

Ford Voltage Regulator Wiring Diagrams.

So quick test for you, turn on your key and see if the field wire is energized. Yes? No?

Now you wired the truck, I can't see. Look at the schematic you used. are you powering the Reg I term from the source schematic shows? If you chose to power I term from the coil wire at the coil, you may be using reduced voltage instead of Battery voltage. The Reg needs to know true Battery voltage all the time so it can control the Alternators output all the time.

Don't hook your Volt meter to the Alt. It should be hooked to a source when the ign switch is in the on/run position. It should not be powered when the truck parked.

The alternator body is held together with 3 bolts/screws. There are three sections to the ALT, front, center, rear(terminal end). Remove the three fasteners and CAREFULLY separate the front from the middle JUST enough to rotate the front section to the position that will place terms toward to passenger side as you described. The sections are on a taper and a slight taping may be needed to loosen. Align and reinstall the fasteners

 

Thanks for the insight. Hooking the voltmeter to a constant hot was dumb I don't know why I did it that way haha.

I didn't have the "I" terminal hooked up to the voltage regulator (or to an ignition source) as it wasn't hooked up that way to begin with but it makes sense as to why it would need to be connected seeing as how (if I've got this correct) it is where the power initiates from.

Answers:
I have an electronic voltage regulator.
I have 10 volts going to the field post when key is on.
As far as "factory for the most part" I should've said everything is factory wiring aside from the horn relay which p.o. took out and replaced with aftermarket air horn.

 

Welcome to FTE!

Appears question has been answered, great link, wish I had access installing alternator a few days ago. Strongly suggest bookmarking the source.

Although a duplication, though I would post a link to diag. used to install the connections at the Alt. .

http://i300.photobucket.com/albums/n...v.jpg~original

Again, welcome to FTE, looking forward to your input; post pic's if and when you can.

 

Thanks gents, problem solved.

Resolution:
Connected "I" terminal to positive post of coil.
Moved the Stator wire back to "Sta" on back of Alt.
Moved voltmeter to an ignition fuse on fuse block.

Time to shrink wrap wires, wet sand and buff, and get ready for the southwest nationals

 

Good looking truck. I like it! Small followup.

1- I see ballast resistor on fire wall, so you have reduced voltage to the I term of V Reg using the wire at coil. Ideally, would like to see source to I term come from where Ford intended it, But quickest way, hook wire to I term, to Key side of the ballast resistor. You want battery voltage at the I term,

2- Are you still using Idiot light on dash? If so is it working properly?

3- What kind of IGN. pts/condenser, Pertronics? Are you aware of the original Pink wire in harness the was the resistance for the Pts/Cond when truck was born? Has the Pink wire been eliminated?

4- Assuming you have a factory OEM ignition switch. At harness plug in to the switch, there is an external stud. Test it with a test light no power key off and power on in the run or acc positions. That stud is where you want to hook the volt meter. You want to get a nice true reading on your volt meter, not a lesser reading because traveling more wiring.

Just trying to help search out any glitches or gremlins.

 

Hey, good eye. I'm trying to make this as much of a daily driver as possible so I want to make sure things are correct. Your input is greatly appreciated.

1. I will move the "I" wire to the key side of the ballast resistor.

2. There is a spot in my gauge cluster just below the speedometer where a light should go. However it just has a red plastic cover for it with no light behind it. I'm not sure if that's where the idiot light was on custom cabs or not but it doesn't work. And I've never messed with it as I plan on going with "Classic Instruments" later on down the line.

3 & 4. It does have the pink resistor wire and the original ignition with a post which is hot when the key is on. I will move my voltmeter to.

Anything else you can think of?

Thanks again.

 

The Pink wire would be there stock with NO ballast resistor. In the original harness it joined up with wire that goes to the I terminal of the starter solenoid. The joining is after or coil side of the pink wire. When solenoid is energized it send full battery voltage to the coil for easier starting. When solenoid is released from start the pink wire supplies reduced voltage to the coil. Reduced voltage is for long life to the pts without burning and pitting and good coil life.

SO, are your pink wire and the ballast resistor both being used? With possibly to low a voltage when running. Are you running a Ford coil or after market? Some aftermarket coils have the resistor built into the coil. Coil terms marked with + and - , aftermarket, or Dist and Batt, Ford?

 

I'm assuming aftermarket coil (+/-) it is not internationally regulated. I have the ballast resistor for the mallory distributor in order to not fry the module. The pink resistor wire is functional and connected.

While running I now have 14 volts on battery, voltmeter, and engine runs while battery disconnected (couple seconds to test Alt.)

 

On coil, do you have writing saying, "use with external resistor"? or not to?

On Mallory dizzy, your install or PO? If PO and if you do not have, I would go online to find Mallory install info for your set up. See wiring schematic. With engine running check the voltage at the + term of coil. And I'm sure you know + gets power into coil and - goes to dizzy.

Just because, I can't say why, but don't disconnect battery with engine running with an Alternator system. I think possibly damaging electronic regulator or possibly something like diodes in the alt. Plus you have a electronically controled Dizzy.

Another "need to mention", Ford alternators have a what I call a window charging rate. Example, if you have a dead battery and you boost your truck and get it running. Then say you want to see if it is charging properly, you hook test volt meter to the battery and you only get say 13.40 volts. Oh my, I must have a bad Alt. NOT SO, as the battery voltage comes up, so will the charging rate. When the battery gets to be 3/4 to Fully charged that charging rate will be around 14.20 volts and if you put your headlights and heater on hi and rev the engine to about 2,000 RPM and the Charge rate stays at 14.20, you have a good charging system.

I could go on and on but enough for now.

 

I actually noticed that the charge rate went up earlier. The battery hadn't been fully charged and started off with 13... let it sit for a min with the headlights on, went up to 14.

Anyways, the distributor was the p.o. install however I replaced my module when I fried it due to me taking the ballast resistor off. When I hooked the new module up I wired according to Mallory specs with ballast. Popped the cover and tested volts and all that good stuff... Moral of the story, it was a pain and I see why Mallory is out of business now but I wasn't looking to spend the money to get a more rugged Distributor. Thanks for your help llcap. Feel free to email me anytime.

 

Enjoy that show your going to. I'll have to see if there is an East Coast Show.