So I have been trying to fix a charging problem in my truck for a few days now. I replaced the voltage regulator and alternator (autozone) but still wasn't having any luck. The PO had this truck totally screwed up when it came to the wiring, which I still trying to figure out. So yesterday I found a yellow wire coming from the cab that was cut off. I also found a wire coming from the regulator that was not hook up, so I connected the two together. So using the multimeter I showed 12.45v at the battery (engine off), but once I hooked up the two wires I'm know showing 16.9 volts with the truck running/charging. Prior to hooking the wires up I was not getting anything to charge. So the old questions is isn't that too much voltage running ? I'm would assume that the voltage regulator is not working correctly? I actually tried another new voltage regulator and the problem still exist.
Shouldn't I be running 14.5v or so when charging correctly? What will happen if I continue to run the truck with 16.9 volts? What would burn up first?
I was initially happy that I found the problem to my charging issues, but know I thinking I still have problems?? The truck is a 1970 f100 with a 300 I6.

Thanks for the input.
Jim

 

Hello Jim,
Too much coming out of the alternator will over charge the battery. The Battery's casing will actually swell. It sounds like when you connected those two wires you tripped the regulator to allow the alternator to put out it's full charge. What is you gauge or light showing?

 

The alternator gauge on the dash shows it peg on C. Before that I thought the gauge didn't work as it was always in the middle. Is there a way to reset the regulator? When I took it to autozone they tested it and it always show it was the voltage regulator. Auto zone also told me that the alternator I bought has a build in regulator and I didn't need to have my original regulator hook up. I find that hard to believe. Electrical is not my strong point. Come to think about it basic mechanical is not my strong point! I tried to different/new regulators and I get the same reading. I'm assuming it probably not wired right.

Thanks Jeff

 

Internally regulated? Ahhh. Yes, that could be a little different. Sounds like maybe you ought to use the seach engine top of this page. Search for "3g alternator set up" or maybe "installing 3g alternator". There are numerous threads from guys going to that alternator and explaining how they changed the wiring. That might coinside with your set up.
BTW, your welcome.

 

if he has the 3G swap, he wouldn't need the voltage regulator on the radiator support.

 

Yep Greg. According to what his parts supplier told him it sounded like the 3G swap or something like it to me.

 

or that the counter guy at Autozone doesn't have a clue what he is talking about. Most of them can barely use the computer to find anything. I have even less faith that they know anything about what they are looking up. This is not true for all of them and some results may vary.

 

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So here's the pic of a wiring coupler? that comes from the cab. The red wire was cut off about 2 inches after the coupler/ harness. I also noticed a yellow wire from the regulator that went to "A" on the regulator not connected. So prior to connecting these two wires I had no charging, after I hook them up I went to 16.9 volts of charging. So it appears my wires are crossed???

Thanks

 

If that new alternator is indeed internally regulated I would be more interested on how you hooked the wires up to it. 2X Gembone up above. With an internally regulated alternator the factory reg is not used and wiring changed to delete it.

 

Jim, I just PM'd HioSilver for you. He always has awesome schematics.

 

Cool, thanks Jeff, I don't think the alternator has the internal regulator as it had the same part number as my old one, which I had to use my original regulator. It's funny I had the truck for quite a few months now, so I would believe that at one time it was charging correctly. The more I dig the more I find when it comes to the wiring of this truck. I'm going to take a closer look after work today.

Thanks

 

Hio PM'd me back and told me where to go. Kuddos to HioSilver.
Jim, go to:
www.bcbroncos.com/instructions08.html

 

Thanks for the info, but after reviewing the link I don't think my alternator is one of the ones mention in the link. I have the standard alternator with the fld wire, batt. wire and sta wire connections plus the ground. Not knowing about the history of the truck is tough, but I highly doubt that the PO put a 3g conversion on this truck. He had some much different wires going all over the place with different colors and wired together without connectors. I must have pulled 2 miles of wires that were not used for basic truck operations. I'll just keep plugging away at it and see what I can find. Thank goodness I'm not using the truck as a daily driver.

Jim