I believe the middle wire is the charge indicator wire, maybe it's broke, or the new alternator is not supplying power to it

 

^^^^^what that feller from north caroliner said.^^^^^

 

I'll post trouble shoot pictures and wire tomorrow. These are called 1 wire, but are really 3 wire

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That's the key on wire. Charge is white.

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Idk. I'll look it up.used to be green/red tracer wire is key

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,.....

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Found this, but on a Ranger. Is that "wht/blk" wire something that should be internal?

 

This is what I have. There is no terminal in the (D) Dummy socket.

 

This page has a picture of the alternator system. It shows only the two wires, plus the black/orange power wire.

Wiring Harness 2001 Ford F-250 7.3L

I need assistance finding where a positive cable on the wiring harness connects to. Starting system positive cables One positive battery cable connects from the battery to the starter relay and the other to the starter motor. Of course if you have two batteries there is one that connects the...

www.freeautomechanic.com

 

Then it would be the lamp ignition wire, is the fuse good. Is there 14ish volts present while running?

 

Yes . . . the CTS2 and the dash gauge agree.

 

Are you sure that the alternator is charging the batteries?

The alternator gets it's exciter voltage from the wire from the light on the dash. Without this voltage the alternator will not begin to charge.

I went through this with another member either here or on TDS and he finally found a broken wire, but he was not charging and it was on a OBS truck so the diagram that I am posting here may not have the correct wire colors for a Super Duty but you may get the idea since the alternators are the same.

 

Are you sure that the alternator is charging the batteries?

The alternator gets it's exciter voltage from the wire from the light on the dash. Without this voltage the alternator will not begin to charge.

I went through this with another member either here or on TDS and he finally found a broken wire, but he was not charging and it was on a OBS truck so the diagram that I am posting here may not have the correct wire colors for a Super Duty but you may get the idea since the alternators are the same.

Thanks for that. My 94 is sort of charging. Guage in dash not working battery light sometimes on. Been a nightmare to figure out

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Yes, it is charging the batteries, as per Autozone test, as well as my multimeter, and the CTS2 gauge.

Actually, going by memory, the wires are the same colors.

 

Well, I had noted that the alternator charging rate was fluctuating, and had gotten as high as 14.6v. I swapped it out at Autozone.

Damned idiot light is still on. I don't get it. Grrrrrr

Dash charging meter shows it dead center, and the CTS2 shows it charging 13.8. This is so annoying.

 

It's almost like there is a wire pulled out of a connection. You were playing with the ignition wires trying to get your truck to start. Is it possible one of those wires is also for the battery light?

 

l ended up buying a whole new engine wire harness. So, that's not it.

 

Having the same trouble with my 94 doc, and I replaced all those. I'm thinking circuit board problem on the back of the gauges.

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How is it a simple alternator swap could do that?

It worked fine.

The alternator failed.

New alternator in and working. Light doesn't go out.

You'd think there is some code to be cleared, but . . .

 

How is it a simple alternator swap could do that?

It worked fine.

The alternator failed.

New alternator in and working. Light doesn't go out.

You'd think there is some code to be cleared, but . . .

Mine was fine before I pulled the engine. Same alternator went back in. When/if I figure it out I'll let you know

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Probably fried the resistor for the light.

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Have you tried grounding the wire that goes back to the light?

A resistor is fairly robust and it takes quite a bit to take one out, plus you would quite likely smell it if it did burn.

Since the light gets it's power from the ignition switch grounding the alternator side of it should turn it off and give you something else to look at.

 

Have you tried grounding the wire that goes back to the light?

A resistor is fairly robust and it takes quite a bit to take one out, plus you would quite likely smell it if it did burn.

Since the light gets it's power from the ignition switch grounding the alternator side of it should turn it off and give you something else to look at.

I just did. No good. The two sides must be equal for it to go off. I have to figure out why they are not.

 

This is the charge light circuit

 

Here's my thought . . . But what can be causing the voltage difference?

 

Have you verified the output voltage to the wire going to the indicator light from the plug. Without that wire hooked up


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Have you verified the output voltage to the wire going to the indicator light from the plug. Without that wire hooked up

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Both the plug side and the wire side say near-zero volts on the light green/red.

The autozone guy says it should have battery voltage on the light green / red wire.

 

Yes, I have battery / alternator voltage at the connecting fuses.

 

If I'm reading that correctly you do not have voltage coming out of the alternator to the indicator charge wire which would suggest another bad alternator

 

I thought so, but the AutoZone guy said no. The wire was to provide the 12V so that the regulator "started". I cannot find anything that says either way.

 

Thats on the other wire it is called the exciter wire or signal. The alternator has to be given power for it to start the charging process.

 

The "A" wire has battery voltage. it is the "I" Wire that does not - nor does the alternator side where the I wire goes in. (Bottom red circle in the pic above.)

 

I'm on my way home I'll test mine out so you can see if there is a difference