Regulator bad? for sure?

[data89]

I've suddenly found that my alternator is not charging. And why do these things always happen on a Sunday in the middle of nowhere?

Okay, so I had the alternator tested at Autozone and it tested fine. I assume, then, it has to be the voltage regulator. I pulled one I had saved off the shelf (I thought I had saved it because it was good) and installed it, but, still it would not charge. So, maybe it's bad too. The question is, if the alternator is good, is it for sure that the regulator is bad!

A new original is $38, and a compatible one is $22. I have used aftermarket parts like this with good success. Is a compatible regulator good enough? Either way, if it turns out the new regulator (whichever one) does not solve the problem, I'm out the money because you can't return it.

But, the problem has to be the regulator, right? (wiring and fuses are all good). 1969 C10 stepside, 250.

[MARKDTN]

I would just swap to a later internal regulator alternator, just jumper the outer 2 wires at the regulator and jumper the inner 2 wires. If you want to keep the alternator you have and replace a regulator, I would go back with a solid state one from a Ford unless this is a perfect restoration. The solid state ones IMHO last longer and work better than the mechanical type. Below are the terminal descriptions at the regulator that should work. I can't find exactly what I was looking for but this should be it. Although I have not done one myself, I have seen them done and they work well.

FORD
I Charge Lamp
A +
S Stator, alt terminal
F Field, alt terminal

GM
F Field
2 Stator
3 +
4 Charge lamp

[cdowns]

do you have a good ground on the regulator?

[data89]

Originally Posted by cdowns

do you have a good ground on the regulator?

Absolutely, no question.

[data89]

Still not charging!!! Okay, here's the deal: I had the alternator checked by Autozone and it passed fine. I put a new regulator on. The ground is good, the wires are good, the battery checks good (one year old), no fuses blown, and no shorts. Yet, it does not charge.
I get 12.44 volts across the battery terminals with the truck running. When I turn on the lights and heater fan, it drops to 12.23 volts even when revving the engine to about 2000 or more RPM.
What am I missing?

[502ms]

Originally Posted by data89

Still not charging!!! Okay, here's the deal: I had the alternator checked by Autozone and it passed fine. I put a new regulator on. The ground is good, the wires are good, the battery checks good (one year old), no fuses blown, and no shorts. Yet, it does not charge.
I get 12.44 volts across the battery terminals with the truck running. When I turn on the lights and heater fan, it drops to 12.23 volts even when revving the engine to about 2000 or more RPM.
What am I missing?

2 things:
Make sure the plug is plugged in securely to the alternator as well as the voltage regulator.
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[data89]

I know the harness connector to the VR is locked in tight, and the wires on the alternator are bolted on. I'm going to check continuity of those wires again.

By the way, is the contact tab underneath the VR for the return wire from the charge lamp (idiot light)?

My idiot light does not function, there is no wire nearby that would have come from the light to the VR. I have to think that when the generator was changed to an alternator system, it was just not hooked up. Can I just connect an ammeter in place of the idiot light in the circuit?

[data89]

Re-checked the wires, all show proper voltage/continuity. Still no charging.
battery static is 12.48v, when running 12.22v, when lights and heater fan on 12.03v revved to 2000-3000. I'm beginning to think, although the alternator tested fine, that it must be the alternator. Any other thoughts??

Curious though, I can take short trips, 3 to 10 miles 10 times and the battery voltage never drops. If I go 100 miles, I run out of juice and it has to be jumped. And even though there wasn't enough juice to start the engine, once started it will go another 50 miles. Wonder if this is significant?

[data89]

For anyone following this, I've found the answer. In checking the color of the wires from the field terminal and stator on the alternator, they were reversed. For whatever reason the plug fits in both upside down and rightside up. Reversed the plug and everything charges properly.
Thanks to everyone trying to help.