Alternator not charging -UPDATED-

[oddball]

One more possibility I thought about, my truck has the amp gauge and it doesnt work. I dont know if the cluster was swapped in or original. I thought it was only on 68 and newer trucks but does it matter if it isnt connected or is that only for trucks with the idiot light?

[fordman]

take the battery to the parts store and get it tested. i wouldn't worry abotu the amp guage right now. unless you are planning on redoing all of the wiring.

[willowbilly3]

The amp gauges rarely work and poorly if at all. Put in a volt meter.
I always check first for a system drain, then bypass the voltage regulator to see if it charges. 9 times out of ten the regulator will be bad and the alt. still good. Get an oem reg if you need one, aftermarket are all junk.

[oddball]

Ok the alternator still isnt charging. Here is what I have done/checked, Replaced charging harness with a known good harness, checked continuity of battery and field wires of that harness, tried three different voltage regulators, checked and cleaned all grounds, checked voltage at the alternator with engine on and off, same as battery about 12.5 volts, and checked for shorts-none. I pulled the positive cable off the battery and the engine dies. I did a full field test and the alternator did start charging up past 15 volts. I checked some other stuff that I cant remember. Ok so as far as ground wires go I have battery to block, back of engine to firewall, and two from alternator. I dont have one from body to frame, is this a possibility? Is there another wire that is needed for charging that I should check? Isnt there an exciter wire coming from the ignition switch? Ive studied the wiring diagram on here but I couldnt tell. There has to be something Im overlooking. This is driving me nuts, I appreciate the help and patience

[fordman]

all alternators need exciter wires. i don't know if yours has one from the switch but it should have one in the wiring. you could try grounding the frame to body and see if that helps. another thing to check would be the fuses and the back of the fuse box. maybe a wire has rusted off of its post. it can and has happened to other guys trucks.

[bumpside]

In the pictures you posted, I don't see any wire from the alternator going to the battery post of the solonid. If you look at wire #38 from the alternator and wire# 152 from the regulator they are spliced together from the factory( large rubber bump on wire). Those two wires turn in to wire#38A. That wire goes to the battery side of the solonid and makes the alternator charge the battery. It would also explain why your truck dies when you take the positive side battery wire off. You have no voltage from the alernator to keep the truck running.------------------- I think the wire you want is the black wire you spliced to the red wire on your truck. The picture doesn't show where it comes from or where it goes to, but it appears there is no wire from the alternator going to the solonid.

[oddball]

Its there, I replaced the charging harness. The pictures were from the old harness that I removed for the camera. The red wires were for some junk aftermarket gauges . The truck ran for many years on that old hacked up harness

[fordman]

look down in the other no charge post the exciter wire is purple and goes to the inst cluster amp guage. or from whihc ever way it works.

[oddball]

Thats what I was trying to figure out. I saw it posted here when I searched but I couldnt find it the second time

[fordman]

here is the link. http://www.fordification.com/forum/view ... =8&t=36170

[oddball]

My truck is a 67 and has the ammeter so I hope the wires are the same color as the 71s

[Thunderfoot]

My truck is a 67 and has the ammeter so I hope the wires are the same color as the 71s

Your 67 will not have the Purple colored wire but instead will have a Green / Red wire to the ignition and it may tie into the Red / Green green wire for the ignition coil on the way.
It will be close to that diagram I posted in the other thread and you can also look at this diagram http://www.fordification.com/images/sch ... arging.jpg as it is one for the Amp gauge but has a differant Voltage Regulator setup, but wiring will still be about the same. Try those test that I listed in the other thread to check that the "Exciter wire" is getting voltage to tell the alternator to start charging.

[oddball]

Ok I performed the check at the regulator, A and S have 12.5 volts, F is grounding, is this correct? I looked at the wires coming from the ignition switch and there isnt any green/red wire. I think the exciter might be one of the black ones but Im not sure. They all have power with key on except a red with blue stripe, it doesnt get any power. Thanks for the help I think I might be getting closer to figuring out the problem

[Thunderfoot]

The picture you have is of the "Ignition switch" and yes the exciter wire is the small black wire that is on the stud in the center, this is wire #98 in this diagram http://www.fordification.com/images/sch ... gauges.jpg if you follow this wire on the diagram it turns into #904 a Green/red striped wire to the Voltage Regulator. Check that the power is getting all the way to the connector on the voltage regulator on this Green /red striped wire.
Sorry for all the differant wire diagrams that show the wire color just a bit different in places here and there, but the overall connection is still the same too/at the Voltage Regulator.

[Thunderfoot]

A and S have 12.5 volts, F is grounding, is this correct?

just re-read this... Does your Voltage Regultor only have 3 wires going to it????? If so can you take a picture of it? That would be the one that has an external "Field Relay" and that could be the problem... and that is where the exciter wire goes to... Let me know...