Charging problems 18 VOLTS

[thedomgardner]

Hey guys. So I have a 1983 F350 with the 6.9. My old alternator died…11 volts while running…so I installed a new one. I also installed a new voltage regulator from NAPA, along with a new connector on the regulator. I have voltage at all times on the “A” terminal on the regulator and have voltage on the “S” terminal with the key on. I also grounded the body of the regulator to the ground on the alternator because I heard that can be a problem. After all of this it is still charging at 18 volts! I’m at a loss on what the problem can be. Everything is new and tight. Thanks in advance for the help.

 

[The_Josh_Bear]

Welcome to the forums. My only experience with something like this is when I ran my alt without the sense wire hooked up, and because it couldn't detect(sense) the voltage it just went full field. My first thought would be to check that you have continuity from the sense wire, see the yellow wire below. Labeled "A".

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I would grab a voltmeter and check that you have 12v(whatever your batteries are at currently) inside the pigtail at the yellow (A)wire. After that check the ground has continuity as well. After that I'm not much good for help on this system.
Oh I lied, if that fues link above feeding B+ is fried or cracked, you'll get the same result, since the regulator can't sense 12v. So according to the diagram if you don't have 12v at the back of the alt(B+) with engine off, you have a busted fuse link. If you have 12v at B+ and none at A, your issue is within the yellow wire or regulator.

Hope that helps!
Joshua

 

[thedomgardner]

Thanks for the help Josh. I have 12v at the big lug on the alternator, and I have 12v at “A” on the pigtail. I threw old regulator back in and got same results. Maybe my luck and have 2 bad regulators? Dumb question with the fusible link…where is it? Although I have 12v at the big lug so I guess it doesn’t matter. I’m having a hard time tracing the wires. Haha

Edit: Went and bought ANOTHER regulator, this time from Advance and got the same result. I’m at a loss

 

[ihc1470]

Disconnect the field wire at the alternator which is the black wire in the picture and see what happens. It should not charge. If it does that correctly then unplug the harness connector from the regulator and see if by chance you can measure voltage on that wire, you should not see any voltage if all is correct. Sounds like the alternator is in full field condition. Slight possibility that the yellow and black wire are making a connection with each other from poor insulation.

Probable not the issue but you might just try running a ground wire from the alternator over to the battery negative terminal to rule out a ground issue.

 

[thedomgardner]

Disconnect the field wire at the alternator which is the black wire in the picture and see what happens. It should not charge. If it does that correctly then unplug the harness connector from the regulator and see if by chance you can measure voltage on that wire, you should not see any voltage if all is correct.

Unplugged field wire, it did stop charging. Measured voltage at the regulator harness, showed 0 volts.

 

[IDIBRONCO]

Here's a freebie. Check the wires around your voltage regulator. About 30 years ago, I had a truck where one of those wires had cracked insulation around it. It was laying against the body and grounding out (1979 F150). It also caused the regulator to burn out. A tape job on the wire, a new regulator, all new bulbs (except for the instrument cluster), and it was going just fine again. Those were the good old days when you could buy all of the stuff at Wal-Mart.

 

[thedomgardner]

Wires look good from what I can see. I’m really starting to wonder if I just ended up with 2 bad part store regulators…

 

[IDIBRONCO]

That could be.

 

[Jesus Freak]

Just remember in the episode of Knight Rider called "knight lines" the bad guy was putting bombs in the electrical boxes of a building that was being built. And the bad guy was paying the contractor to do it..........so what did they use as props for bombs?....... you guessed it Ford voltage regulators........ so, think twice before you shoot voltage to that baby, it could be a left over prop from Knight Rider.....

But really, it's the regulator, or a janky wire between here and there, nuttin to it!

 

[thedomgardner]

Scratch what I said before…it does still charge with field wire unplugged. Does that mean my new alternator is bad?

Edit: FIGURED IT OUT. My multi meter reads 4 volts high I guess. Borrowed my dad meter just to rule mine out…says 13.2 volts. Even though 0 is 0, I guess 13 means 17 haha. Thanks for the help guys, glad I can go to bed peacefully tonight.

 

[IDIBRONCO]

Scratch what I said before…it does still charge with field wire unplugged. Does that mean my new alternator is bad?

Edit: FIGURED IT OUT. My multi meter reads 4 volts high I guess. Borrowed my dad meter just to rule mine out…says 13.2 volts. Even though 0 is 0, I guess 13 means 17 haha. Thanks for the help guys, glad I can go to bed peacefully tonight.

There's another guy who still gets on here once in a while who had the same issue a few years back. He went so far as to tear into his 3g alternator, rebuilt it, messed around with the wiring, and then found out that his DVOM wasn't reading correctly. So don't feel bad. You're not the first. On the other hand, this is a good example of why I like to run an aftermarket voltmeter, among other gauges.

 

[thedomgardner]

On the other hand, this is a good example of why I like to run an aftermarket voltmeter, among other gauges.

I planned on getting some A pillar gauges, maybe I’ll be doing that sooner than later now.

 

[IDIBRONCO]

I planned on getting some A pillar gauges, maybe I’ll be doing that sooner than later now.

That's never a bad idea. Quality gauges aren't cheap, but they sure can save you some headaches.

 

[The_Josh_Bear]

Thanks for the help Josh. I have 12v at the big lug on the alternator, and I have 12v at “A” on the pigtail. I threw old regulator back in and got same results. Maybe my luck and have 2 bad regulators? Dumb question with the fusible link…where is it? Although I have 12v at the big lug so I guess it doesn’t matter. I’m having a hard time tracing the wires. Haha

Edit: Went and bought ANOTHER regulator, this time from Advance and got the same result. I’m at a loss

Scratch what I said before…it does still charge with field wire unplugged. Does that mean my new alternator is bad?

Edit: FIGURED IT OUT. My multi meter reads 4 volts high I guess. Borrowed my dad meter just to rule mine out…says 13.2 volts. Even though 0 is 0, I guess 13 means 17 haha. Thanks for the help guys, glad I can go to bed peacefully tonight.

How does the same meter read 12v volts at the battery and 18v at 13.2v charging?!?

 

[IDIBRONCO]

How does the same meter read 12v volts at the battery and 18v at 13.2v charging?!?

It's wrong. It's probably reading exponentially wrong. In other words, the higher the voltage that it's reading, the farther off the reading that it shows is. Or it may just get to a voltage level and then shoot it's own readout way up there. Either way, it would end up getting the BFH if it was mine!