I am here seeking help with my truck that will not charge. I have recently replaced my alternator, because although the old one was still charging, it was not keeping up as well as I would have liked, so I replaced it. When I replaced it I also changed out my carb and instead of wiring the choke to the stator, I just tapped into my radio switch power behind the dash. I don’t really know too much about wiring but to my understanding there is some sort of an exciter wire that tells the alternator to start charging when you turn the key on. I have replaced my alternator, voltage regulator, and staring selinoid and have had no changes, so this leaves me to believe wiring is my issue. Also, this truck has a factory ammeter and no warning light. Any ideas on how I can get this thing to charge?
P.S. Just read over this and forgot to mention that this is a 1981 F150 with a straight 6

 

It is probably wiring related and will require some diagnostics. Before we jump to that make sure all the connections are clean and making contact. This applies to the regulator plug and the terminals on the solenoid. Double check those and if you still have issues let us know and I can walk you through the testing procedure. You will need a DVOM and a couple of jumper wires a few feet long.

 

I have already checked these things. What could be my next step in diagnostics?

 

Ok we have identified that your truck has an ampmeter So that is out of the way.

Step 1 Ignition off, regulator unplugged
Unplug the regulator.
Check for Bat power on the Black/Orange hash wire at the regulator
If no power go to step 1A
If power go to step 2

Step 1A Ignition off

Check for Bat power at the Yellow /White dot wire on the Alt If no power Repair fuse link J on Bat side of Starter solenoid
If power repair splice between the Black/Orange hash and Yellow /White dot wire


Step 2. Ignition off, regulator unplugged
Check for Bat power at the Yellow /White dot wire on the Alt
If power go to Step 3
If no power repair splice between the Black/Orange hash and Yellow /White dot wire



Step 3, Ignition off, regulator unplugged
Check continuity on the feild wire between the regulator and the Alt Orange Light brown hash wire
If continuity Go to step 4
If not repair circuit

Step 4 Ignition on in run, regulator unplugged

Check for Bat power on the Light Green/Red hash wire at the regulator.
If power report back for further testing.
If no power report back for further testing.

 

Ok I will do those tests momentarily, however before I do, I just want to make sure I actually have my wires hooked up to the correct studs on the alternator. I will post a picture of the alternator and my Hanes diagram right after this. The only two wires I have going to the alternator are the one coming from the positive side of my solenoid, and the wire going directly into my regulator from the alternator. If you could just confirm which stud they go on I would greatly appreciate it.

 

Here’s the photos

 

The battery goes to the labelled Battery (BAT) Red-collar, Regulator goes to the one labelled Field (FLD) White-collar

 

Field terminal on the alternator goes to the "F" terminal on the regulator.

Large terminal with the nut on the alternator goes to the battery or the solenoid battery connection like you said.

There should be a yellow wire on the "A" terminal of the regulator. This should go to the battery + also, or the solenoid connection, or however it's hooked in there that gets it to the battery +.

There is one other connection, and it's important. If someone has been messing with the wiring behind the dash, it can get messed up. On the "S" terminal of the regulator there should be a green/red wire. This is shown in your diagram, but what terminal it uses is not spelled out, on your setup it goes to the "S" terminal of the reg.. You need to unplug the regulator plug, get a testlight, and see if you have power on this wire with the keyswitch in run. If you don't, that is a problem. You can hot wire this wire temporarily to the battery + and then see if it starts charging. If it does, you have verified this is your problem. If you leave this wire on the battery + it will run the battery down with the engine off, so you need to find a key-on power source for this wire.

P.S. Also make sure the regulator is grounded. They usually have a small ground wire under one of the mounting bolts.

 

BTW, you said you hooked up your choke to ignition. That won't affect the charging system but it will make the choke open too fast. The Ford choke connects to stator and only gets 1/2 voltage.

 

well I actually changed this, and now my choke won’t open because I have a Holley four barrel on the motor now and according to Holley I need 12v switch power. But good to know that’s not related

 

Ok so two things. Number 1, what should I be grounding too when testing this wire? My multimeter is going nuts and is jumping around anywhere between 2 volts and 40 volts while trying to test this wire. Secondly, how could I ground my regulator? Isn’t it already grounded to the chassis being that it’s bolted to the fender?

 

I was using my multi meter incorrectly. Had it in the wrong mode lol. I have confirmed that I do have ignition switch power on that green and red wire. My question about grounding the regulator box still stands, and also where do I go from here?

 

Thing is that 12 volts should only be when the motor is running NOT when ever the key is turned on.
2 way to do this use a relay and trigger it from that wire that went to the choke as it will only have power when the ALT is spinning / Motor running.
OR
put a Tee on the oil psi port so you can run the sender for the oil gauge / light and then get a switch that closes when the motor is running and have oil psi.
The 12 volt wire goes in 1 side of this new switch and the other out to the choke.

Grounding the REG box.
Pull it off the fender and take sand paper and clean down to metal where it mounts. Also do the REG where the bolts go both sides and bolt it back in place.
You can then take your meter and go from the REG case to the battery NEG post and see what you get, should not have any resistance.

Someone that know this system a little better and has started to help should be back to help.
Dave ----

 

Most of the regulators I have seen have a short wire coming from the harness that is grounding the regulator under one of the mounting bolts. The fender on my 89 is plastic, so just the mounting bolt is no good on that model. If you want to be sure, you can make a short wire, crimp a ring terminal on one end and put it on one of the mounting bolts, and run the other end to a known good ground. Don't know if you have room on the battery terminal itself, or there is some other place handy to ground it, like the metal fender itself. You could possibly use one of the mounting bolts that mount the starter solenoid, it needs a ground also and must have a good one if it's working.

Once you are sure the reg is grounded, try it. I would put your meter on the battery with the engine off, and read the voltage. Then start the truck up and with the engine running, read the voltage again. See what you get.

On the choke, I have never ran a holley 12v choke. But I am using a Ford 12v choke on my Bronco, and it is wired to the alternator 7v connection. It seems to work fine that way for me. If you want to try it you could see if it works for you. It would be a little cleaner and if you have a little trouble starting it in the future, the choke won't be pulling off making matters worse. That's the problem with hooking it up to the keyswitch, each time you try to get it running, it's sending power to the choke opening it up.

 

Well everyone thank you for your help. I have figured out my issue, and it may or may not be a surprise to some of you. The brand new regulator I bought was no good. I began to get suspicious when I went on a test ride and turned off all accessories and noticed my voltage had only dropped from 11.85 to 11.83 in about a 20 minute drive around my neighborhood. (I know voltage should be higher, but as you all know why it wasn’t due to this issue) I started thinking that the motor alone with the ignition components has to be drawing more then that so I came to the conclusion that I was charging, just not as much as I should. Quick trip to the parts store to get a second new regulator, and my problem is gone.

This is the second part I’ve bought from a parts store within a month that has been bad out of the box. Earlier in October I got a bad distributor out of the box from Napa, and now this. Just some food for thought for anyone having electrical part related issues in the future.

I do appreciate everyone’s time, and will definitely be lookin into the advice given on getting my choke to only warm up when my engine is running. Have a great night everyone! Thanks again